TY  - JOUR
AU  - Vasiljević, Jadranka
AU  - Jovanović, Vladimir P.
AU  - Tomović, Aleksandar
AU  - Timotijević, Dejan
AU  - Žikić, Radomir
AU  - Belic, Milivoj
AU  - Jović-Savić, Dragana M.
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2147
AB  - We demonstrate transitional dimensionality of discrete diffraction in radial-elliptical photonic lattices. Varying the order, characteristic structure size, and ellipticity of the Mathieu beams used for the photonic lattices generation, we control the shape of discrete diffraction distribution over the combination of the radial direction with the circular, elliptic, or hyperbolic. We also investigate the transition from one-dimensional to two-dimensional discrete diffraction by varying the input probe beam position. The most pronounced discrete diffraction is observed along the crystal anisotropy direction.
PB  - Optica Publishing Group
T2  - Optics Express
T1  - Interdimensional radial discrete diffraction in Mathieu photonic lattices
EP  - 28953
IS  - 18
SP  - 28946
VL  - 31
DO  - 10.1364/OE.497795
ER  - 

@article{
author = "Vasiljević, Jadranka and Jovanović, Vladimir P. and Tomović, Aleksandar and Timotijević, Dejan and Žikić, Radomir and Belic, Milivoj and Jović-Savić, Dragana M.",
year = "2023",
abstract = "We demonstrate transitional dimensionality of discrete diffraction in radial-elliptical photonic lattices. Varying the order, characteristic structure size, and ellipticity of the Mathieu beams used for the photonic lattices generation, we control the shape of discrete diffraction distribution over the combination of the radial direction with the circular, elliptic, or hyperbolic. We also investigate the transition from one-dimensional to two-dimensional discrete diffraction by varying the input probe beam position. The most pronounced discrete diffraction is observed along the crystal anisotropy direction.",
publisher = "Optica Publishing Group",
journal = "Optics Express",
title = "Interdimensional radial discrete diffraction in Mathieu photonic lattices",
pages = "28953-28946",
number = "18",
volume = "31",
doi = "10.1364/OE.497795"
}

Vasiljević, J., Jovanović, V. P., Tomović, A., Timotijević, D., Žikić, R., Belic, M.,& Jović-Savić, D. M.. (2023). Interdimensional radial discrete diffraction in Mathieu photonic lattices. in Optics Express
Optica Publishing Group., 31(18), 28946-28953.
https://doi.org/10.1364/OE.497795

Vasiljević J, Jovanović VP, Tomović A, Timotijević D, Žikić R, Belic M, Jović-Savić DM. Interdimensional radial discrete diffraction in Mathieu photonic lattices. in Optics Express. 2023;31(18):28946-28953.
doi:10.1364/OE.497795 .

Vasiljević, Jadranka, Jovanović, Vladimir P., Tomović, Aleksandar, Timotijević, Dejan, Žikić, Radomir, Belic, Milivoj, Jović-Savić, Dragana M., "Interdimensional radial discrete diffraction in Mathieu photonic lattices" in Optics Express, 31, no. 18 (2023):28946-28953,
https://doi.org/10.1364/OE.497795 . .

TY  - CONF
AU  - Jovanović, Vladimir P.
AU  - Tomović, Aleksandar
AU  - Dražić, Miloš
AU  - Djurišić, Ivana
AU  - Žikić, Radomir
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2169
AB  - Here in this talk, we propose the simultaneous measurement of rectification and amplitude of tunneling current during electrical probing of a molecule in a nanogap for efficient single-molecule detection. Also, we suggest the application of nitrogen-terminated graphene or CNT nanogaps due to their inherent outstanding features. With DFT and Non-Equilibrium Green's Function formalism, we show that tunneling current through various molecules, including ssDNA, TATP, or small organics placed in those nanogaps, exhibits unique rectification behavior under square pulses of alternating bias. The rectification arises by on-off switching of electronic transport through the molecular HOMO or LUMO levels, sustained by partial charging of the probed molecule, generated by asymmetric hybridization of that level with Bloch states from one of the electrodes. An effect that mimics local gating, i. e. an interaction between the molecule and the nitrogen-induced dipole moment located at the N-C interface of the electrode ends, strongly influences the rectification. The simultaneous measurement of rectification and amplitude of tunneling current could be applied to gas-phase single-molecule detection, as shown in the example case of the TATP. The TATP (triacetone triperoxide) is a volatile, potent, and hard-to-detect explosive made from commonly available chemicals, a terrorist weapon of choice in the last two decades. The rectification could also be applied in the liquid phase, offering the possibility of high-throughput and precise DNA sequencing. We found that the environment (neighboring nucleotides, water molecules, and counterions) does not mask ssDNA rectification while ssDNA traverses the nanogap.
PB  - Institute of Physics Belgrade
C3  - The 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade
T1  - Single-Molecule Probing By Rectification in a Nanogap
SP  - 74
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2169
ER  - 

@conference{
author = "Jovanović, Vladimir P. and Tomović, Aleksandar and Dražić, Miloš and Djurišić, Ivana and Žikić, Radomir",
year = "2023",
abstract = "Here in this talk, we propose the simultaneous measurement of rectification and amplitude of tunneling current during electrical probing of a molecule in a nanogap for efficient single-molecule detection. Also, we suggest the application of nitrogen-terminated graphene or CNT nanogaps due to their inherent outstanding features. With DFT and Non-Equilibrium Green's Function formalism, we show that tunneling current through various molecules, including ssDNA, TATP, or small organics placed in those nanogaps, exhibits unique rectification behavior under square pulses of alternating bias. The rectification arises by on-off switching of electronic transport through the molecular HOMO or LUMO levels, sustained by partial charging of the probed molecule, generated by asymmetric hybridization of that level with Bloch states from one of the electrodes. An effect that mimics local gating, i. e. an interaction between the molecule and the nitrogen-induced dipole moment located at the N-C interface of the electrode ends, strongly influences the rectification. The simultaneous measurement of rectification and amplitude of tunneling current could be applied to gas-phase single-molecule detection, as shown in the example case of the TATP. The TATP (triacetone triperoxide) is a volatile, potent, and hard-to-detect explosive made from commonly available chemicals, a terrorist weapon of choice in the last two decades. The rectification could also be applied in the liquid phase, offering the possibility of high-throughput and precise DNA sequencing. We found that the environment (neighboring nucleotides, water molecules, and counterions) does not mask ssDNA rectification while ssDNA traverses the nanogap.",
publisher = "Institute of Physics Belgrade",
journal = "The 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade",
title = "Single-Molecule Probing By Rectification in a Nanogap",
pages = "74",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2169"
}

Jovanović, V. P., Tomović, A., Dražić, M., Djurišić, I.,& Žikić, R.. (2023). Single-Molecule Probing By Rectification in a Nanogap. in The 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade
Institute of Physics Belgrade., 74.
https://hdl.handle.net/21.15107/rcub_rimsi_2169

Jovanović VP, Tomović A, Dražić M, Djurišić I, Žikić R. Single-Molecule Probing By Rectification in a Nanogap. in The 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade. 2023;:74.
https://hdl.handle.net/21.15107/rcub_rimsi_2169 .

Jovanović, Vladimir P., Tomović, Aleksandar, Dražić, Miloš, Djurišić, Ivana, Žikić, Radomir, "Single-Molecule Probing By Rectification in a Nanogap" in The 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade (2023):74,
https://hdl.handle.net/21.15107/rcub_rimsi_2169 .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Miljkovic, Helena
AU  - Dražić, Miloš
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2148
AB  - Triacetone triperoxide (TATP) is a highly potent homemade explosive commonly used in terrorist
attacks. Its detection poses a significant challenge due to its volatility, and the lack of portability of
current sensing techniques. To address this issue, we propose a novel approach based on singlemolecule TATP detection in the air using a device where tunneling current in N-terminated carbonnanotubes nanogaps is measured. By employing the density functional theory combined with the nonequilibrium Green’s function method, we show that current of tens of nanoamperes passes through
TATP trapped in the nanogap, with a discrimination ratio of several orders of magnitude even against
prevalent indoor volatile organic compounds (VOCs). This high tunneling current through TATP’s highest
occupied molecular orbital (HOMO) is facilitated by the strong electric field generated by N–C polar
bonds at the electrode ends and by the hybridization between TATP and the electrodes, driven by oxygen atoms within the probed molecule. The application of the same principle is discussed for graphene
nanogaps and break-junctions.
PB  - RSC
T2  - Physical Chemistry Chemical Physics
T1  - Tunnel junction sensing of TATP explosive at the single-molecule level
EP  - 26658
IS  - 39
SP  - 26648
VL  - 25
DO  - 10.1039/d3cp02767h
ER  - 

@article{
author = "Tomović, Aleksandar and Miljkovic, Helena and Dražić, Miloš and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2023",
abstract = "Triacetone triperoxide (TATP) is a highly potent homemade explosive commonly used in terrorist
attacks. Its detection poses a significant challenge due to its volatility, and the lack of portability of
current sensing techniques. To address this issue, we propose a novel approach based on singlemolecule TATP detection in the air using a device where tunneling current in N-terminated carbonnanotubes nanogaps is measured. By employing the density functional theory combined with the nonequilibrium Green’s function method, we show that current of tens of nanoamperes passes through
TATP trapped in the nanogap, with a discrimination ratio of several orders of magnitude even against
prevalent indoor volatile organic compounds (VOCs). This high tunneling current through TATP’s highest
occupied molecular orbital (HOMO) is facilitated by the strong electric field generated by N–C polar
bonds at the electrode ends and by the hybridization between TATP and the electrodes, driven by oxygen atoms within the probed molecule. The application of the same principle is discussed for graphene
nanogaps and break-junctions.",
publisher = "RSC",
journal = "Physical Chemistry Chemical Physics",
title = "Tunnel junction sensing of TATP explosive at the single-molecule level",
pages = "26658-26648",
number = "39",
volume = "25",
doi = "10.1039/d3cp02767h"
}

Tomović, A., Miljkovic, H., Dražić, M., Jovanović, V. P.,& Žikić, R.. (2023). Tunnel junction sensing of TATP explosive at the single-molecule level. in Physical Chemistry Chemical Physics
RSC., 25(39), 26648-26658.
https://doi.org/10.1039/d3cp02767h

Tomović A, Miljkovic H, Dražić M, Jovanović VP, Žikić R. Tunnel junction sensing of TATP explosive at the single-molecule level. in Physical Chemistry Chemical Physics. 2023;25(39):26648-26658.
doi:10.1039/d3cp02767h .

Tomović, Aleksandar, Miljkovic, Helena, Dražić, Miloš, Jovanović, Vladimir P., Žikić, Radomir, "Tunnel junction sensing of TATP explosive at the single-molecule level" in Physical Chemistry Chemical Physics, 25, no. 39 (2023):26648-26658,
https://doi.org/10.1039/d3cp02767h . .

TY  - CONF
AU  - Tomović, Aleksandar
AU  - Miljkovic, Helena
AU  - Dražić, Miloš
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2170
AB  - Triacetone triperoxide (TATP) is a homemade, potent explosive and, unfortunately, is used in many terrorist attacks. It is hard to detect, and present techniques for its sensing do not offer portability. Fortunately, TATP is volatile, and gas-sensing-based devices for TATP detection would provide a higher level of safety. Here, we explore the possibility of single molecule TATP detection in the air by tunneling current measurement in the N-terminated carbon-based nanogaps, at the DFT+NEGF level of theory. We found TATP averaged current amplitude of tens nano amperes, with a discrimination ratio with respect to prevalent indoor volatile organic compounds (VOC) of a few orders of magnitude. That high tunneling current is due to specific TATP HOMO contributions to electronic transport. The transport facilitates the strong, in-gap electrical field generated by N-C polar bonds from electrode ends and TATP electrode hybridization, spurred by oxygen atoms from a probed molecule.
PB  - Institute of Physics Belgrade
C3  - 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade
T1  - Tunnel Junction Sensing of TATP Explosive at the Single-Molecule Level
SP  - 95
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2170
ER  - 

@conference{
author = "Tomović, Aleksandar and Miljkovic, Helena and Dražić, Miloš and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2023",
abstract = "Triacetone triperoxide (TATP) is a homemade, potent explosive and, unfortunately, is used in many terrorist attacks. It is hard to detect, and present techniques for its sensing do not offer portability. Fortunately, TATP is volatile, and gas-sensing-based devices for TATP detection would provide a higher level of safety. Here, we explore the possibility of single molecule TATP detection in the air by tunneling current measurement in the N-terminated carbon-based nanogaps, at the DFT+NEGF level of theory. We found TATP averaged current amplitude of tens nano amperes, with a discrimination ratio with respect to prevalent indoor volatile organic compounds (VOC) of a few orders of magnitude. That high tunneling current is due to specific TATP HOMO contributions to electronic transport. The transport facilitates the strong, in-gap electrical field generated by N-C polar bonds from electrode ends and TATP electrode hybridization, spurred by oxygen atoms from a probed molecule.",
publisher = "Institute of Physics Belgrade",
journal = "21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade",
title = "Tunnel Junction Sensing of TATP Explosive at the Single-Molecule Level",
pages = "95",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2170"
}

Tomović, A., Miljkovic, H., Dražić, M., Jovanović, V. P.,& Žikić, R.. (2023). Tunnel Junction Sensing of TATP Explosive at the Single-Molecule Level. in 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade
Institute of Physics Belgrade., 95.
https://hdl.handle.net/21.15107/rcub_rimsi_2170

Tomović A, Miljkovic H, Dražić M, Jovanović VP, Žikić R. Tunnel Junction Sensing of TATP Explosive at the Single-Molecule Level. in 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade. 2023;:95.
https://hdl.handle.net/21.15107/rcub_rimsi_2170 .

Tomović, Aleksandar, Miljkovic, Helena, Dražić, Miloš, Jovanović, Vladimir P., Žikić, Radomir, "Tunnel Junction Sensing of TATP Explosive at the Single-Molecule Level" in 21st Symposium on Condensed Matter Physics - SFKM 2023, Belgrade (2023):95,
https://hdl.handle.net/21.15107/rcub_rimsi_2170 .

TY  - JOUR
AU  - Djurišić, Ivana
AU  - Jovanović, Vladimir P.
AU  - Dražić, Miloš
AU  - Tomović, Aleksandar
AU  - Žikić, Radomir
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1493
AB  - The electrical current properties of single-molecule sensing devices based on electronic (tunneling) transport strongly depend on molecule frontier orbital energy, spatial distribution, and position with respect to the electrodes. Here, we present an analysis of the bias dependence of molecule frontier orbital properties at an exemplar case of DNA nucleotides in the gap between H-terminated (3, 3) carbon nanotube (CNT) electrodes and its relation to transversal current rectification. The electronic transport properties of this simple single-molecule device, whose characteristic is the absence of covalent bonding between electrodes and a molecule between them, were obtained using density functional theory and non-equilibrium Green's functions. As in our previous studies, we could observe two distinct bias dependences of frontier orbital energies: the so-called strong and the weak pinning regimes. We established a procedure, from zero-bias and empty-gap characteristics, to estimate finite-bias electronic tunneling transport properties, i.e., whether the molecular junction would operate in the weak or strong pinning regime. We also discuss the use of the zero-bias approximation to calculate electric current properties at finite bias. The results from this work could have an impact on the design of new single-molecule applications that use tunneling current or rectification applicable in high-sensitivity sensors, protein, or DNA sequencing.
PB  - MDPI, Basel
T2  - Nanomaterials
T1  - Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap
IS  - 11
VL  - 11
DO  - 10.3390/nano11113021
ER  - 

@article{
author = "Djurišić, Ivana and Jovanović, Vladimir P. and Dražić, Miloš and Tomović, Aleksandar and Žikić, Radomir",
year = "2021",
abstract = "The electrical current properties of single-molecule sensing devices based on electronic (tunneling) transport strongly depend on molecule frontier orbital energy, spatial distribution, and position with respect to the electrodes. Here, we present an analysis of the bias dependence of molecule frontier orbital properties at an exemplar case of DNA nucleotides in the gap between H-terminated (3, 3) carbon nanotube (CNT) electrodes and its relation to transversal current rectification. The electronic transport properties of this simple single-molecule device, whose characteristic is the absence of covalent bonding between electrodes and a molecule between them, were obtained using density functional theory and non-equilibrium Green's functions. As in our previous studies, we could observe two distinct bias dependences of frontier orbital energies: the so-called strong and the weak pinning regimes. We established a procedure, from zero-bias and empty-gap characteristics, to estimate finite-bias electronic tunneling transport properties, i.e., whether the molecular junction would operate in the weak or strong pinning regime. We also discuss the use of the zero-bias approximation to calculate electric current properties at finite bias. The results from this work could have an impact on the design of new single-molecule applications that use tunneling current or rectification applicable in high-sensitivity sensors, protein, or DNA sequencing.",
publisher = "MDPI, Basel",
journal = "Nanomaterials",
title = "Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap",
number = "11",
volume = "11",
doi = "10.3390/nano11113021"
}

Djurišić, I., Jovanović, V. P., Dražić, M., Tomović, A.,& Žikić, R.. (2021). Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap. in Nanomaterials
MDPI, Basel., 11(11).
https://doi.org/10.3390/nano11113021

Djurišić I, Jovanović VP, Dražić M, Tomović A, Žikić R. Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap. in Nanomaterials. 2021;11(11).
doi:10.3390/nano11113021 .

Djurišić, Ivana, Jovanović, Vladimir P., Dražić, Miloš, Tomović, Aleksandar, Žikić, Radomir, "Predicting Finite-Bias Tunneling Current Properties from Zero-Bias Features: The Frontier Orbital Bias Dependence at an Exemplar Case of DNA Nucleotides in a Nanogap" in Nanomaterials, 11, no. 11 (2021),
https://doi.org/10.3390/nano11113021 . .

TY  - JOUR
AU  - Djurišić, Ivana
AU  - Dražić, Miloš
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1412
AB  - The requirement for controllable frontier orbital energy shift in single-molecule devices based on electronic (tunneling) transport yielded several rules for device design that lean on molecular level pinning to the electrochemical potential of nano-electrodes. We previously found that the pinning (designated as the strong pinning) was the consequence of the bias-induced molecular charge accumulation related to the hybridization of the highest occupied molecular orbital (HOMO) with one of the electrodes. However, in the wide bias range, only "partial" pinning (designated as the weak pinning) happens. In this work, we address the bias-induced shift of molecular orbitals in a weak pinning regime, where no hybridization or covalent bonds with electrodes exist. We found using density functional theory coupled with non-equilibrium Green's functions that the energy shift of frontier molecular orbitals of benzene and nicotine, placed between H-terminated (3, 3) CNTs, in weak pinning regime, is driven only by the electrostatic potential energy of an empty gap. For nicotine, whose HOMO and LUMO (lowest unoccupied molecular orbital) are located on different sides of the gap center, we show that the HOMO-LUMO energy gap changes with bias. We developed a theoretical model of a dielectric in a gap to depict this behavior. Application-wise, we expect that the weak pinning effect would be observable in novel single-molecule sensors based on electronic transport and molecular rectifying as long as the system exhibits a non-resonant behavior, and could serve for molecular gap tuning in single-molecule readout such as DNA, RNA and protein sequencing, or harmful single-molecule detection in gas phase.
PB  - Springer, Dordrecht
T2  - Journal of Nanoparticle Research
T1  - Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps
IS  - 1
VL  - 23
DO  - 10.1007/s11051-021-05139-y
ER  - 

@article{
author = "Djurišić, Ivana and Dražić, Miloš and Tomović, Aleksandar and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2021",
abstract = "The requirement for controllable frontier orbital energy shift in single-molecule devices based on electronic (tunneling) transport yielded several rules for device design that lean on molecular level pinning to the electrochemical potential of nano-electrodes. We previously found that the pinning (designated as the strong pinning) was the consequence of the bias-induced molecular charge accumulation related to the hybridization of the highest occupied molecular orbital (HOMO) with one of the electrodes. However, in the wide bias range, only "partial" pinning (designated as the weak pinning) happens. In this work, we address the bias-induced shift of molecular orbitals in a weak pinning regime, where no hybridization or covalent bonds with electrodes exist. We found using density functional theory coupled with non-equilibrium Green's functions that the energy shift of frontier molecular orbitals of benzene and nicotine, placed between H-terminated (3, 3) CNTs, in weak pinning regime, is driven only by the electrostatic potential energy of an empty gap. For nicotine, whose HOMO and LUMO (lowest unoccupied molecular orbital) are located on different sides of the gap center, we show that the HOMO-LUMO energy gap changes with bias. We developed a theoretical model of a dielectric in a gap to depict this behavior. Application-wise, we expect that the weak pinning effect would be observable in novel single-molecule sensors based on electronic transport and molecular rectifying as long as the system exhibits a non-resonant behavior, and could serve for molecular gap tuning in single-molecule readout such as DNA, RNA and protein sequencing, or harmful single-molecule detection in gas phase.",
publisher = "Springer, Dordrecht",
journal = "Journal of Nanoparticle Research",
title = "Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps",
number = "1",
volume = "23",
doi = "10.1007/s11051-021-05139-y"
}

Djurišić, I., Dražić, M., Tomović, A., Jovanović, V. P.,& Žikić, R.. (2021). Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps. in Journal of Nanoparticle Research
Springer, Dordrecht., 23(1).
https://doi.org/10.1007/s11051-021-05139-y

Djurišić I, Dražić M, Tomović A, Jovanović VP, Žikić R. Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps. in Journal of Nanoparticle Research. 2021;23(1).
doi:10.1007/s11051-021-05139-y .

Djurišić, Ivana, Dražić, Miloš, Tomović, Aleksandar, Jovanović, Vladimir P., Žikić, Radomir, "Electrostatically driven energy shift of molecular orbitals of benzene and nicotine in carbon nanotube gaps" in Journal of Nanoparticle Research, 23, no. 1 (2021),
https://doi.org/10.1007/s11051-021-05139-y . .

TY  - JOUR
AU  - Djurišić, Ivana
AU  - Dražić, Miloš
AU  - Tomović, Aleksandar
AU  - Spasenović, Marko
AU  - Šljivančanin, Zeljko
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1405
AB  - Functionalization of electrodes is a wide-used strategy in various applications ranging from single-molecule sensing and protein sequencing, to ion trapping, to desalination. We demonstrate, employing non-equilibrium Green ' s function formalism combined with density functional theory, that single-species (N, H, S, Cl, F) termination of graphene nanogap electrodes results in a strong in-gap electrostatic field, induced by species-dependent dipoles formed at the electrode ends. Consequently, the field increases or decreases electronic transport through a molecule (benzene) placed in the nanogap by shifting molecular levels by almost 2 eV in respect to the electrode Fermi level via a field effect akin to the one used for field-effect transistors. We also observed the local gating in graphene nanopores terminated with different single-species atoms. Nitrogen-terminated nanogaps (NtNGs) and nanopores (NtNPs) show the strongest effect. The in-gap potential can be transformed from a plateau-like to a saddle-like shape by tailoring NtNG and NtNP size and termination type. In particular, the saddle-like potential is applicable in single-ion trapping and desalination devices.
PB  - Wiley-V C H Verlag Gmbh, Weinheim
T2  - Chemphyschem
T1  - Field Effect and Local Gating in Nitrogen-Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene
EP  - 341
IS  - 3
SP  - 336
VL  - 22
DO  - 10.1002/cphc.202000771
ER  - 

@article{
author = "Djurišić, Ivana and Dražić, Miloš and Tomović, Aleksandar and Spasenović, Marko and Šljivančanin, Zeljko and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2021",
abstract = "Functionalization of electrodes is a wide-used strategy in various applications ranging from single-molecule sensing and protein sequencing, to ion trapping, to desalination. We demonstrate, employing non-equilibrium Green ' s function formalism combined with density functional theory, that single-species (N, H, S, Cl, F) termination of graphene nanogap electrodes results in a strong in-gap electrostatic field, induced by species-dependent dipoles formed at the electrode ends. Consequently, the field increases or decreases electronic transport through a molecule (benzene) placed in the nanogap by shifting molecular levels by almost 2 eV in respect to the electrode Fermi level via a field effect akin to the one used for field-effect transistors. We also observed the local gating in graphene nanopores terminated with different single-species atoms. Nitrogen-terminated nanogaps (NtNGs) and nanopores (NtNPs) show the strongest effect. The in-gap potential can be transformed from a plateau-like to a saddle-like shape by tailoring NtNG and NtNP size and termination type. In particular, the saddle-like potential is applicable in single-ion trapping and desalination devices.",
publisher = "Wiley-V C H Verlag Gmbh, Weinheim",
journal = "Chemphyschem",
title = "Field Effect and Local Gating in Nitrogen-Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene",
pages = "341-336",
number = "3",
volume = "22",
doi = "10.1002/cphc.202000771"
}

Djurišić, I., Dražić, M., Tomović, A., Spasenović, M., Šljivančanin, Z., Jovanović, V. P.,& Žikić, R.. (2021). Field Effect and Local Gating in Nitrogen-Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene. in Chemphyschem
Wiley-V C H Verlag Gmbh, Weinheim., 22(3), 336-341.
https://doi.org/10.1002/cphc.202000771

Djurišić I, Dražić M, Tomović A, Spasenović M, Šljivančanin Z, Jovanović VP, Žikić R. Field Effect and Local Gating in Nitrogen-Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene. in Chemphyschem. 2021;22(3):336-341.
doi:10.1002/cphc.202000771 .

Djurišić, Ivana, Dražić, Miloš, Tomović, Aleksandar, Spasenović, Marko, Šljivančanin, Zeljko, Jovanović, Vladimir P., Žikić, Radomir, "Field Effect and Local Gating in Nitrogen-Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene" in Chemphyschem, 22, no. 3 (2021):336-341,
https://doi.org/10.1002/cphc.202000771 . .

TY  - JOUR
AU  - Jovanović, Vladimir P.
AU  - Raffy, H.
AU  - Li, Z. Z.
AU  - Remenyi, G.
AU  - Monceau, P.
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1442
AB  - We studied the in-plane angular magnetoresistance (AMR), in the normal state, of underdoped superconducting Sr1-xLaxCuO2, which has the simplest crystal structure among cuprates. The measurements of two underdoped thin films with different dopings were performed in intense magnetic field H (up to 22 T). The longitudinal magnetoresistance at temperature T is negative and scales with HIT. For both samples, the AMR is anisotropic and shows an unexpected dependence on H intensity. While at the low magnetic field, one observes essentially twofold AMR oscillations for the more doped sample, fourfold ones start to grow under the high magnetic field, resulting in the coexistence of the two. For the less doped film at the low magnetic field, both twofold and fourfold AMR components exist. With the increase of the magnetic field, the fourfold component survives a pi/4 phase shift, during which its amplitude vanishes, at a magnetic field such as 16 T  lt  H-c  lt  17 T. As a result, at the high magnetic field above H-c, the angular dependence of the in-plane magnetoresistance turns out to be the same for both samples. We tentatively ascribe the above features to the presence of antiferromagnetism in the CuO2 planes of underdoped Sr1-xLaxCuO2.
PB  - Amer Physical Soc, College Pk
T2  - Physical Review B
T1  - High magnetic-field evolution of the in-plane angular magnetoresistance of electron-doped Sr1-xLaxCuO2 in the normal state
IS  - 1
VL  - 103
DO  - 10.1103/PhysRevB.103.014520
ER  - 

@article{
author = "Jovanović, Vladimir P. and Raffy, H. and Li, Z. Z. and Remenyi, G. and Monceau, P.",
year = "2021",
abstract = "We studied the in-plane angular magnetoresistance (AMR), in the normal state, of underdoped superconducting Sr1-xLaxCuO2, which has the simplest crystal structure among cuprates. The measurements of two underdoped thin films with different dopings were performed in intense magnetic field H (up to 22 T). The longitudinal magnetoresistance at temperature T is negative and scales with HIT. For both samples, the AMR is anisotropic and shows an unexpected dependence on H intensity. While at the low magnetic field, one observes essentially twofold AMR oscillations for the more doped sample, fourfold ones start to grow under the high magnetic field, resulting in the coexistence of the two. For the less doped film at the low magnetic field, both twofold and fourfold AMR components exist. With the increase of the magnetic field, the fourfold component survives a pi/4 phase shift, during which its amplitude vanishes, at a magnetic field such as 16 T  lt  H-c  lt  17 T. As a result, at the high magnetic field above H-c, the angular dependence of the in-plane magnetoresistance turns out to be the same for both samples. We tentatively ascribe the above features to the presence of antiferromagnetism in the CuO2 planes of underdoped Sr1-xLaxCuO2.",
publisher = "Amer Physical Soc, College Pk",
journal = "Physical Review B",
title = "High magnetic-field evolution of the in-plane angular magnetoresistance of electron-doped Sr1-xLaxCuO2 in the normal state",
number = "1",
volume = "103",
doi = "10.1103/PhysRevB.103.014520"
}

Jovanović, V. P., Raffy, H., Li, Z. Z., Remenyi, G.,& Monceau, P.. (2021). High magnetic-field evolution of the in-plane angular magnetoresistance of electron-doped Sr1-xLaxCuO2 in the normal state. in Physical Review B
Amer Physical Soc, College Pk., 103(1).
https://doi.org/10.1103/PhysRevB.103.014520

Jovanović VP, Raffy H, Li ZZ, Remenyi G, Monceau P. High magnetic-field evolution of the in-plane angular magnetoresistance of electron-doped Sr1-xLaxCuO2 in the normal state. in Physical Review B. 2021;103(1).
doi:10.1103/PhysRevB.103.014520 .

Jovanović, Vladimir P., Raffy, H., Li, Z. Z., Remenyi, G., Monceau, P., "High magnetic-field evolution of the in-plane angular magnetoresistance of electron-doped Sr1-xLaxCuO2 in the normal state" in Physical Review B, 103, no. 1 (2021),
https://doi.org/10.1103/PhysRevB.103.014520 . .

TY  - JOUR
AU  - Djurišić, Ivana
AU  - Dražić, Miloš
AU  - Tomović, Aleksandar
AU  - Spasenović, Marko
AU  - Sljivancanin, Zeljko
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2020
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1346
AB  - Fast, reliable, and inexpensive DNA sequencing is an important pursuit in healthcare, especially in personalized medicine with possible deep societal impacts. Despite significant progress in various nanopore-based sequencing configurations, challenges that remain in resolution and chromosome-size-long readout call for new approaches. Here we found strong rectification in the transversal current during single-stranded DNA translocation through a nanopore with side-embedded N-terminated carbon nanotube electrodes. Employing density functional theory and nonequilibrium Green's function formalisms, we show that the rectifying ratio (response to square pulses of alternating bias) bears high nucleobase specificity. Rectification arises because of bias-dependent resistance asymmetry on the deoxyribonucleotide-electrode interfaces. The asymmetry induces molecular charging and highest occupied molecular orbital pinning to the electrochemical potential of one of the electrodes, assisted by an in-gap electric-field effect caused by dipoles at the terminated electrode ends. We propose the rectifying ratio, due to its order-of-magnitude-difference nucleobase selectivity and robustness to electrode-molecule orientation, as a promising readout quantifier for single-base resolution and chromosome-size-long single-read DNA sequencing. The proposed configurations are within experimental reach from the viewpoint of both nanofabrication and small current measurement.
PB  - Amer Chemical Soc, Washington
T2  - Acs Applied Nano Materials
T1  - DNA Sequencing with Single-Stranded DNA Rectification in a Nanogap Gated by N-Terminated Carbon Nanotube Electrodes
EP  - 3043
IS  - 3
SP  - 3034
VL  - 3
DO  - 10.1021/acsanm.0c00385
ER  - 

@article{
author = "Djurišić, Ivana and Dražić, Miloš and Tomović, Aleksandar and Spasenović, Marko and Sljivancanin, Zeljko and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2020",
abstract = "Fast, reliable, and inexpensive DNA sequencing is an important pursuit in healthcare, especially in personalized medicine with possible deep societal impacts. Despite significant progress in various nanopore-based sequencing configurations, challenges that remain in resolution and chromosome-size-long readout call for new approaches. Here we found strong rectification in the transversal current during single-stranded DNA translocation through a nanopore with side-embedded N-terminated carbon nanotube electrodes. Employing density functional theory and nonequilibrium Green's function formalisms, we show that the rectifying ratio (response to square pulses of alternating bias) bears high nucleobase specificity. Rectification arises because of bias-dependent resistance asymmetry on the deoxyribonucleotide-electrode interfaces. The asymmetry induces molecular charging and highest occupied molecular orbital pinning to the electrochemical potential of one of the electrodes, assisted by an in-gap electric-field effect caused by dipoles at the terminated electrode ends. We propose the rectifying ratio, due to its order-of-magnitude-difference nucleobase selectivity and robustness to electrode-molecule orientation, as a promising readout quantifier for single-base resolution and chromosome-size-long single-read DNA sequencing. The proposed configurations are within experimental reach from the viewpoint of both nanofabrication and small current measurement.",
publisher = "Amer Chemical Soc, Washington",
journal = "Acs Applied Nano Materials",
title = "DNA Sequencing with Single-Stranded DNA Rectification in a Nanogap Gated by N-Terminated Carbon Nanotube Electrodes",
pages = "3043-3034",
number = "3",
volume = "3",
doi = "10.1021/acsanm.0c00385"
}

Djurišić, I., Dražić, M., Tomović, A., Spasenović, M., Sljivancanin, Z., Jovanović, V. P.,& Žikić, R.. (2020). DNA Sequencing with Single-Stranded DNA Rectification in a Nanogap Gated by N-Terminated Carbon Nanotube Electrodes. in Acs Applied Nano Materials
Amer Chemical Soc, Washington., 3(3), 3034-3043.
https://doi.org/10.1021/acsanm.0c00385

Djurišić I, Dražić M, Tomović A, Spasenović M, Sljivancanin Z, Jovanović VP, Žikić R. DNA Sequencing with Single-Stranded DNA Rectification in a Nanogap Gated by N-Terminated Carbon Nanotube Electrodes. in Acs Applied Nano Materials. 2020;3(3):3034-3043.
doi:10.1021/acsanm.0c00385 .

Djurišić, Ivana, Dražić, Miloš, Tomović, Aleksandar, Spasenović, Marko, Sljivancanin, Zeljko, Jovanović, Vladimir P., Žikić, Radomir, "DNA Sequencing with Single-Stranded DNA Rectification in a Nanogap Gated by N-Terminated Carbon Nanotube Electrodes" in Acs Applied Nano Materials, 3, no. 3 (2020):3034-3043,
https://doi.org/10.1021/acsanm.0c00385 . .

TY  - CONF
AU  - Simonović, Jelena
AU  - Toljić, Boško
AU  - Rasković, Božidar
AU  - Jovanović, Vladimir P.
AU  - Lazarević, M.
AU  - Milošević, Milena
AU  - Nikolić, N.
AU  - Panajotović, R.
AU  - Milašin, J.
PY  - 2019
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1266
AB  - Aim To characterize stem cells originating from different dental tissues (apical papilla [SCAP], dental follicle [DFSC], and pulp [DPSC]) and test the capacity of Raman microspectroscopy to distinguish between the three dental stem cell types. Methods SCAR DFSC, and DPSC cultures were generated from three immature wisdom teeth originating from three patients. Cell stemness was confirmed by inducing neuro-, osteo-, chondro-, and adipo-differentiaton and by mesenchymal marker expression analysis by flow-cytometry and real-time polymerase chain reaction. Cellular components were then evaluated by Raman microspectroscopy. Results We found differences between SCAP, DFSC, and DPSC Raman spectra. The ratio between proteins and nucleic acids (748/770), a parameter for discriminating more differentiated from less differentiated cells, showed significant differences between the three cell types. All cells also displayed a fingerprint region in the 600-700 cm(-1) range, and characteristic lipid peaks at positions 1440 cm(-1) and 1650 cm(-1). Conclusion Although different dental stem cells exhibited similar Raman spectra, the method enabled us to make subtle distinction between them.
PB  - Medicinska Naklada Zagreb
C3  - Croatian Medical Journal
T1  - Raman microspectroscopy: toward a better distinction and profiling of different populations of dental stem cells
EP  - 86
IS  - 2
SP  - 78
VL  - 60
DO  - 10.3325/cmj.2019.60.78
ER  - 

@conference{
author = "Simonović, Jelena and Toljić, Boško and Rasković, Božidar and Jovanović, Vladimir P. and Lazarević, M. and Milošević, Milena and Nikolić, N. and Panajotović, R. and Milašin, J.",
year = "2019",
abstract = "Aim To characterize stem cells originating from different dental tissues (apical papilla [SCAP], dental follicle [DFSC], and pulp [DPSC]) and test the capacity of Raman microspectroscopy to distinguish between the three dental stem cell types. Methods SCAR DFSC, and DPSC cultures were generated from three immature wisdom teeth originating from three patients. Cell stemness was confirmed by inducing neuro-, osteo-, chondro-, and adipo-differentiaton and by mesenchymal marker expression analysis by flow-cytometry and real-time polymerase chain reaction. Cellular components were then evaluated by Raman microspectroscopy. Results We found differences between SCAP, DFSC, and DPSC Raman spectra. The ratio between proteins and nucleic acids (748/770), a parameter for discriminating more differentiated from less differentiated cells, showed significant differences between the three cell types. All cells also displayed a fingerprint region in the 600-700 cm(-1) range, and characteristic lipid peaks at positions 1440 cm(-1) and 1650 cm(-1). Conclusion Although different dental stem cells exhibited similar Raman spectra, the method enabled us to make subtle distinction between them.",
publisher = "Medicinska Naklada Zagreb",
journal = "Croatian Medical Journal",
title = "Raman microspectroscopy: toward a better distinction and profiling of different populations of dental stem cells",
pages = "86-78",
number = "2",
volume = "60",
doi = "10.3325/cmj.2019.60.78"
}

Simonović, J., Toljić, B., Rasković, B., Jovanović, V. P., Lazarević, M., Milošević, M., Nikolić, N., Panajotović, R.,& Milašin, J.. (2019). Raman microspectroscopy: toward a better distinction and profiling of different populations of dental stem cells. in Croatian Medical Journal
Medicinska Naklada Zagreb., 60(2), 78-86.
https://doi.org/10.3325/cmj.2019.60.78

Simonović J, Toljić B, Rasković B, Jovanović VP, Lazarević M, Milošević M, Nikolić N, Panajotović R, Milašin J. Raman microspectroscopy: toward a better distinction and profiling of different populations of dental stem cells. in Croatian Medical Journal. 2019;60(2):78-86.
doi:10.3325/cmj.2019.60.78 .

Simonović, Jelena, Toljić, Boško, Rasković, Božidar, Jovanović, Vladimir P., Lazarević, M., Milošević, Milena, Nikolić, N., Panajotović, R., Milašin, J., "Raman microspectroscopy: toward a better distinction and profiling of different populations of dental stem cells" in Croatian Medical Journal, 60, no. 2 (2019):78-86,
https://doi.org/10.3325/cmj.2019.60.78 . .

TY  - CHAP
AU  - Tomović, Aleksandar
AU  - Djurišić, Ivana
AU  - Žikić, Radomir
AU  - Pejić, Milan
AU  - Jovanović, Vladimir P.
PY  - 2017
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1898
AB  - There is an ongoing interest in organic materials due to their application in various organic electronic devices. However stability of organic materials limits their potential use. They are prone to degradation both during the working life and storage. One of the main causes is extrinsic degradation, under the influence of oxygen and moisture. This problem can be solved by encapsulation of devices. However no encapsulation is perfect. This paper presents a study of interaction of thin films of well-known organic blue emitters, namely N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) and 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi), with UV light in air. Films of both materials are stable in vacuum, but readily degrade in the presence of oxygen. Thus, the necessary condition for interaction (degradation) is the simultaneous presence of UV light and oxygen. Chemical analysis of irradiated films by mass and infrared spectroscopy revealed presence of oxidized species (impurities). These impurities are responsible for increased morphological stability of irradiated films and quenching of photoluminescence (PL). Only small amount of impurities, 0.4 % (0.2 %) for TPD (DPVBi), causes 50 % decrease of PL. This implies a non-trivial mechanism of quenching. For both molecules it was found that distance between impurities is smaller or equal to exciton diffusion length, which is the necessary condition for quenching. Following mechanism of quenching is proposed: exciton diffuses by hopping form one host molecule (DPVBi or TPD) to another through Förster resonant energy transfer in a random walk manner. If, during its lifetime, it comes to proximity of an impurity, a PL quenching process occurs. Findings of this study are important because they show that even a small amount of oxygen that penetrates a blue emitter layer would impair luminescence efficiency of a device. Moreover, the absorption of its own radiation would additionally contribute to the rate of degradation of a device. It is reasonable to expect that transport properties would also be affected when materials are used as a hole-transporting layer in OLEDs.
PB  - Atlantis Press, Paris
T2  - Proceedings of the IV Advanced Ceramics and Applications Conference
T1  - Interaction of UV Irradiation with Thin Films of Organic Molecules
EP  - 347
SP  - 317
DO  - 10.2991/978-94-6239-213-7_23
ER  - 

@inbook{
author = "Tomović, Aleksandar and Djurišić, Ivana and Žikić, Radomir and Pejić, Milan and Jovanović, Vladimir P.",
year = "2017",
abstract = "There is an ongoing interest in organic materials due to their application in various organic electronic devices. However stability of organic materials limits their potential use. They are prone to degradation both during the working life and storage. One of the main causes is extrinsic degradation, under the influence of oxygen and moisture. This problem can be solved by encapsulation of devices. However no encapsulation is perfect. This paper presents a study of interaction of thin films of well-known organic blue emitters, namely N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) and 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi), with UV light in air. Films of both materials are stable in vacuum, but readily degrade in the presence of oxygen. Thus, the necessary condition for interaction (degradation) is the simultaneous presence of UV light and oxygen. Chemical analysis of irradiated films by mass and infrared spectroscopy revealed presence of oxidized species (impurities). These impurities are responsible for increased morphological stability of irradiated films and quenching of photoluminescence (PL). Only small amount of impurities, 0.4 % (0.2 %) for TPD (DPVBi), causes 50 % decrease of PL. This implies a non-trivial mechanism of quenching. For both molecules it was found that distance between impurities is smaller or equal to exciton diffusion length, which is the necessary condition for quenching. Following mechanism of quenching is proposed: exciton diffuses by hopping form one host molecule (DPVBi or TPD) to another through Förster resonant energy transfer in a random walk manner. If, during its lifetime, it comes to proximity of an impurity, a PL quenching process occurs. Findings of this study are important because they show that even a small amount of oxygen that penetrates a blue emitter layer would impair luminescence efficiency of a device. Moreover, the absorption of its own radiation would additionally contribute to the rate of degradation of a device. It is reasonable to expect that transport properties would also be affected when materials are used as a hole-transporting layer in OLEDs.",
publisher = "Atlantis Press, Paris",
journal = "Proceedings of the IV Advanced Ceramics and Applications Conference",
booktitle = "Interaction of UV Irradiation with Thin Films of Organic Molecules",
pages = "347-317",
doi = "10.2991/978-94-6239-213-7_23"
}

Tomović, A., Djurišić, I., Žikić, R., Pejić, M.,& Jovanović, V. P.. (2017). Interaction of UV Irradiation with Thin Films of Organic Molecules. in Proceedings of the IV Advanced Ceramics and Applications Conference
Atlantis Press, Paris., 317-347.
https://doi.org/10.2991/978-94-6239-213-7_23

Tomović A, Djurišić I, Žikić R, Pejić M, Jovanović VP. Interaction of UV Irradiation with Thin Films of Organic Molecules. in Proceedings of the IV Advanced Ceramics and Applications Conference. 2017;:317-347.
doi:10.2991/978-94-6239-213-7_23 .

Tomović, Aleksandar, Djurišić, Ivana, Žikić, Radomir, Pejić, Milan, Jovanović, Vladimir P., "Interaction of UV Irradiation with Thin Films of Organic Molecules" in Proceedings of the IV Advanced Ceramics and Applications Conference (2017):317-347,
https://doi.org/10.2991/978-94-6239-213-7_23 . .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Savić, J. J.
AU  - Bakic, N. Lj.
AU  - Bortel, G.
AU  - Faigel, G.
AU  - Žikić, Radomir
AU  - Jovanović, Vladimir P.
PY  - 2017
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1091
AB  - Prolonged annealing of pentacene thin films in air leads to the formation of nano- and micro-scale rod-shaped structures at temperatures equal to or higher than 130 degrees C. Scanning electron microscopy measurements indicated their crystalline structure, while UV-vis absorption spectra revealed presence of different species of oxidized pentacene, including 6,13-pentacenequinone. The mechanism of growth of microcrystals from oxidized pentacene molecules is discussed. Raman and UV-vis absorption spectra dependences on film thickness (in 30-300 nm range) and on thermal annealing conditions (in air and nitrogen at ambient pressure at 100 and 150 degrees C) were also studied. These spectra are not largely affected by annealing if it is performed in nitrogen at any of studied temperatures and annealing times (few hours to few days). However, if annealing is performed in air, at temperatures 130 degrees C and higher, changes in spectral features are significant due to film oxidation.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Vacuum
T1  - Oxidized pentacene micro-rods obtained by thermal annealing of pentacene thin films in air
EP  - 42
SP  - 36
VL  - 144
DO  - 10.1016/j.vacuum.2017.07.012
ER  - 

@article{
author = "Tomović, Aleksandar and Savić, J. J. and Bakic, N. Lj. and Bortel, G. and Faigel, G. and Žikić, Radomir and Jovanović, Vladimir P.",
year = "2017",
abstract = "Prolonged annealing of pentacene thin films in air leads to the formation of nano- and micro-scale rod-shaped structures at temperatures equal to or higher than 130 degrees C. Scanning electron microscopy measurements indicated their crystalline structure, while UV-vis absorption spectra revealed presence of different species of oxidized pentacene, including 6,13-pentacenequinone. The mechanism of growth of microcrystals from oxidized pentacene molecules is discussed. Raman and UV-vis absorption spectra dependences on film thickness (in 30-300 nm range) and on thermal annealing conditions (in air and nitrogen at ambient pressure at 100 and 150 degrees C) were also studied. These spectra are not largely affected by annealing if it is performed in nitrogen at any of studied temperatures and annealing times (few hours to few days). However, if annealing is performed in air, at temperatures 130 degrees C and higher, changes in spectral features are significant due to film oxidation.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Vacuum",
title = "Oxidized pentacene micro-rods obtained by thermal annealing of pentacene thin films in air",
pages = "42-36",
volume = "144",
doi = "10.1016/j.vacuum.2017.07.012"
}

Tomović, A., Savić, J. J., Bakic, N. Lj., Bortel, G., Faigel, G., Žikić, R.,& Jovanović, V. P.. (2017). Oxidized pentacene micro-rods obtained by thermal annealing of pentacene thin films in air. in Vacuum
Pergamon-Elsevier Science Ltd, Oxford., 144, 36-42.
https://doi.org/10.1016/j.vacuum.2017.07.012

Tomović A, Savić JJ, Bakic NL, Bortel G, Faigel G, Žikić R, Jovanović VP. Oxidized pentacene micro-rods obtained by thermal annealing of pentacene thin films in air. in Vacuum. 2017;144:36-42.
doi:10.1016/j.vacuum.2017.07.012 .

Tomović, Aleksandar, Savić, J. J., Bakic, N. Lj., Bortel, G., Faigel, G., Žikić, Radomir, Jovanović, Vladimir P., "Oxidized pentacene micro-rods obtained by thermal annealing of pentacene thin films in air" in Vacuum, 144 (2017):36-42,
https://doi.org/10.1016/j.vacuum.2017.07.012 . .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Žikić, Radomir
AU  - Savić, Jelena J.
AU  - Bakić, Nataša Lj.
AU  - Jovanović, Vladimir P.
PY  - 2016
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1901
AB  - The influence of thermal annealing (in air and nitrogen at ambient pressure) on optical properties
of pentacene films, well-known material widely used in organic electronic devices, was studied. Pentacene films, whose thickness varies an order of magnitude (30 – 300 nm) depending on the position on the substrate, were polycrystalline at all thicknesses. Raman and UV-vis absorption spectra depend on the position on film implies changes of the film structure with the thickness. These spectra are not largely affected by annealing if it is not performed in air at temperatures higher than 100°C. Prolonged annealing in air, at temperatures higher than 100°C, leads to formation of nano- and micro-scale rod-shaped structures on film surface. Based on scanning electron microscopy measurements, it is supposed that these structures are crystalline. Their UV-vis absorbance indicates that they are composed of more than one species of oxidized pentacene molecules, including 6,13-pentacenequinone. Further study is necessary to precisely determine composition and structure of micro-rods, as well as the mechanism of their formation.
PB  - Serbian Ceramic Society
T2  - ADVANCED CERAMICS AND APPLICATION V - PROGRAM AND THE BOOK OF ABSTRACTS
T1  - Micro-rods of oxidized pentacene obtained by thermal annealing in air of pentacene thin films
SP  - 80
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_1901
ER  - 

@article{
author = "Tomović, Aleksandar and Žikić, Radomir and Savić, Jelena J. and Bakić, Nataša Lj. and Jovanović, Vladimir P.",
year = "2016",
abstract = "The influence of thermal annealing (in air and nitrogen at ambient pressure) on optical properties
of pentacene films, well-known material widely used in organic electronic devices, was studied. Pentacene films, whose thickness varies an order of magnitude (30 – 300 nm) depending on the position on the substrate, were polycrystalline at all thicknesses. Raman and UV-vis absorption spectra depend on the position on film implies changes of the film structure with the thickness. These spectra are not largely affected by annealing if it is not performed in air at temperatures higher than 100°C. Prolonged annealing in air, at temperatures higher than 100°C, leads to formation of nano- and micro-scale rod-shaped structures on film surface. Based on scanning electron microscopy measurements, it is supposed that these structures are crystalline. Their UV-vis absorbance indicates that they are composed of more than one species of oxidized pentacene molecules, including 6,13-pentacenequinone. Further study is necessary to precisely determine composition and structure of micro-rods, as well as the mechanism of their formation.",
publisher = "Serbian Ceramic Society",
journal = "ADVANCED CERAMICS AND APPLICATION V - PROGRAM AND THE BOOK OF ABSTRACTS",
title = "Micro-rods of oxidized pentacene obtained by thermal annealing in air of pentacene thin films",
pages = "80",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_1901"
}

Tomović, A., Žikić, R., Savić, J. J., Bakić, N. Lj.,& Jovanović, V. P.. (2016). Micro-rods of oxidized pentacene obtained by thermal annealing in air of pentacene thin films. in ADVANCED CERAMICS AND APPLICATION V - PROGRAM AND THE BOOK OF ABSTRACTS
Serbian Ceramic Society., 80.
https://hdl.handle.net/21.15107/rcub_rimsi_1901

Tomović A, Žikić R, Savić JJ, Bakić NL, Jovanović VP. Micro-rods of oxidized pentacene obtained by thermal annealing in air of pentacene thin films. in ADVANCED CERAMICS AND APPLICATION V - PROGRAM AND THE BOOK OF ABSTRACTS. 2016;:80.
https://hdl.handle.net/21.15107/rcub_rimsi_1901 .

Tomović, Aleksandar, Žikić, Radomir, Savić, Jelena J., Bakić, Nataša Lj., Jovanović, Vladimir P., "Micro-rods of oxidized pentacene obtained by thermal annealing in air of pentacene thin films" in ADVANCED CERAMICS AND APPLICATION V - PROGRAM AND THE BOOK OF ABSTRACTS (2016):80,
https://hdl.handle.net/21.15107/rcub_rimsi_1901 .

TY  - GEN
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
PY  - 2015
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1903
AB  - There is an ongoing interest in organic materials due to their application in various organic electronic devices. However stability of organic materials limits their potential use. They are prone to degradation both during the working life and storage. One of the main causes is extrinsic degradation, under the influence of oxygen and moisture. This problem can be solved by encapsulation of devices. However no encapsulation is perfect. In the first part of this work a study of degradation of thin films of N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) and 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) under UV irradiation in air is given. Films of both materials are stable in vacuum, but readily degrade in the presence of oxygen. Thus, the necessary condition for degradation is the simultaneous presence of UV light and oxygen. Chemical analysis of irradiated films by NMR, mass and infrared spectroscopy revealed presence of oxidized species (impurities). These impurities are responsible for increased morphological stability of irradiated films and quenching of photoluminescence. Only small amount of impurities, 0.4 % (0.2 %) for TPD (DPVBi), causes 50 % decrease of photoluminescence. This implies a non-trivial mechanism of quenching. For both molecules it was found that distance between impurities is smaller or equal to exciton diffusion length, which is the necessary condition for quenching. Following mechanism of quenching is proposed: exciton diffuses by hopping form one DPVBi (TPD) to another through FRET in a random walk manner. If, during its lifetime, it comes to proximity of an impurity, a Dexter-type energy transfer occurs and PL is quenched. Findings of DPVBi study are important because they show that even a small amount of oxygen that penetrates a DPVBi layer would impair luminescence efficiency of a device. Moreover, the absorption of own radiation (for DPVBi and TPD both) would additionally contribute to the rate of degradation of a device. It is reasonable to expect that transport properties would also be affected when materials are used as a hole-transporting layer in OLEDs.
PB  - Serbian Ceramic Society
T2  - ADVANCED CERAMICS AND APPLICATION IV - PROGRAM AND THE BOOK OF ABSTRACTS
T1  - Interaction of UV irradiation with thin films of organic molecules
SP  - 43
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_1903
ER  - 

@misc{
author = "Tomović, Aleksandar and Jovanović, Vladimir P. and Žikić, Radomir",
year = "2015",
abstract = "There is an ongoing interest in organic materials due to their application in various organic electronic devices. However stability of organic materials limits their potential use. They are prone to degradation both during the working life and storage. One of the main causes is extrinsic degradation, under the influence of oxygen and moisture. This problem can be solved by encapsulation of devices. However no encapsulation is perfect. In the first part of this work a study of degradation of thin films of N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) and 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) under UV irradiation in air is given. Films of both materials are stable in vacuum, but readily degrade in the presence of oxygen. Thus, the necessary condition for degradation is the simultaneous presence of UV light and oxygen. Chemical analysis of irradiated films by NMR, mass and infrared spectroscopy revealed presence of oxidized species (impurities). These impurities are responsible for increased morphological stability of irradiated films and quenching of photoluminescence. Only small amount of impurities, 0.4 % (0.2 %) for TPD (DPVBi), causes 50 % decrease of photoluminescence. This implies a non-trivial mechanism of quenching. For both molecules it was found that distance between impurities is smaller or equal to exciton diffusion length, which is the necessary condition for quenching. Following mechanism of quenching is proposed: exciton diffuses by hopping form one DPVBi (TPD) to another through FRET in a random walk manner. If, during its lifetime, it comes to proximity of an impurity, a Dexter-type energy transfer occurs and PL is quenched. Findings of DPVBi study are important because they show that even a small amount of oxygen that penetrates a DPVBi layer would impair luminescence efficiency of a device. Moreover, the absorption of own radiation (for DPVBi and TPD both) would additionally contribute to the rate of degradation of a device. It is reasonable to expect that transport properties would also be affected when materials are used as a hole-transporting layer in OLEDs.",
publisher = "Serbian Ceramic Society",
journal = "ADVANCED CERAMICS AND APPLICATION IV - PROGRAM AND THE BOOK OF ABSTRACTS",
title = "Interaction of UV irradiation with thin films of organic molecules",
pages = "43",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_1903"
}

Tomović, A., Jovanović, V. P.,& Žikić, R.. (2015). Interaction of UV irradiation with thin films of organic molecules. in ADVANCED CERAMICS AND APPLICATION IV - PROGRAM AND THE BOOK OF ABSTRACTS
Serbian Ceramic Society., 43.
https://hdl.handle.net/21.15107/rcub_rimsi_1903

Tomović A, Jovanović VP, Žikić R. Interaction of UV irradiation with thin films of organic molecules. in ADVANCED CERAMICS AND APPLICATION IV - PROGRAM AND THE BOOK OF ABSTRACTS. 2015;:43.
https://hdl.handle.net/21.15107/rcub_rimsi_1903 .

Tomović, Aleksandar, Jovanović, Vladimir P., Žikić, Radomir, "Interaction of UV irradiation with thin films of organic molecules" in ADVANCED CERAMICS AND APPLICATION IV - PROGRAM AND THE BOOK OF ABSTRACTS (2015):43,
https://hdl.handle.net/21.15107/rcub_rimsi_1903 .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Djurišić, Ivana
AU  - PEJIĆ, MILAN M.
AU  - Cerovski, Viktor
AU  - BLESIĆ, SUZANA M.
AU  - Žikić, Radomir
PY  - 2015
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1892
AB  - U ovom radu je prikazana studija mehanizma gašenja fotoluminescencije (FL) tankih amorfnih filmova N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD) izloženih UV zračenju u vazduhu. TPD je organski molekul koji se često koristi u izradi organskih svetlećih dioda (OLED). Prilikom izlaganja TPD filmova UV zračenju u vazduhu, dolazi do fotooksidacije TPD molekula, te iz tog razloga fotoluminescencija TPD filmova opada eksponencijalno sa vremenom osvetljavanja filmova, odnosno sa povećanjem koncentracije nečistoća nastalih usled fotooksidacije. Intenzitet fotoluminescencije opadne na polovinu svoje početne vrednosti u slučaju kada je 0.4 % nečistoća prisutno u filmu. U tom slučaju je srednje rastojanje između nečistoća (akceptora) šest puta veće od srednjeg rastojanja između TPD molekula (donora). Direktan dugodometni Forsterov transfer energije je odbačen kao mehanizam gašenja fotoluminescencije jer je spektralno preklapanje emisije donora i apsorpcije akceptora zanemarljivo. Iz ovog razloga je postulirana ekscitonska difuzija u TPD filmovima, analogno nalazima u postojećoj literaturi. Prisustvo produkata oksidacije je potvrđeno uz pomoć infracrvene (IR) spektroskopije. Takodje, izračunat je IR spektar koristeći teoriju funkcionala gustine (DFT) i dobijeno je dobro slaganje sa eksperimentalnim rezultatima.
AB  - The mechanism of photoluminescence (PL) quenching of thin amorphous N,N′-bis(3-methylphenyl)- N,N′-bis(phenyl)benzidine (TPD) films exposed to UV light in air is studied. TPD is small organic molecule widely used in production of organic light emmiting devices (OLEDs). Photoluminescence of TPD films decays exponentially with time of irradiation, i.e. with the increase of concentration of impurities (photo-oxidized TPD molecules) generated by UV irradiation in air. Intensity of PL decreases to half of its original value when the concentration of impurities reaches 0.4%. Average distance between impurities (acceptors) is almost an order of magnitude larger than average distance between host TPD molecules (donors). Direct long range Förster energy transfer is ruled out as the mechanism of PL quenching, as the overlap between donor and acceptor is lacking, and exciton self-diffusion in TPD films is postulated for the mechanism. The presence of oxidation products is confirmed by infrared (IR) spectroscopy. Vibrational spectra of TPD molecule and few other possible products of photo-oxidation of TPD molecule, obtained by density functional theory, are compared to experimental IR spectra.
PB  - Savez inženjera i tehničara Srbije, Beograd
T2  - TEHNIKA
T1  - Mehanizam gašenja fotoluminescencije u tankim filmovima N,N′-bis(3- methylphenyl)-N,N′-bis(phenyl)benzidine osvetljenih UV svetlošću u vazduhu
T1  - MECHANISM OF PHOTOLUMINESCENCE QUENCHING IN THIN FILMS OF N,N′-BIS(3- METHYLPHENYL)-N,N′-BIS(PHENYL)BENZIDINE IRRADIATED BY UV LIGHT IN AIR
EP  - 914
IS  - 6
SP  - 909
VL  - 70
DO  - 10.5937/tehnika1506909T
ER  - 

@article{
author = "Tomović, Aleksandar and Jovanović, Vladimir P. and Djurišić, Ivana and PEJIĆ, MILAN M. and Cerovski, Viktor and BLESIĆ, SUZANA M. and Žikić, Radomir",
year = "2015",
abstract = "U ovom radu je prikazana studija mehanizma gašenja fotoluminescencije (FL) tankih amorfnih filmova N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD) izloženih UV zračenju u vazduhu. TPD je organski molekul koji se često koristi u izradi organskih svetlećih dioda (OLED). Prilikom izlaganja TPD filmova UV zračenju u vazduhu, dolazi do fotooksidacije TPD molekula, te iz tog razloga fotoluminescencija TPD filmova opada eksponencijalno sa vremenom osvetljavanja filmova, odnosno sa povećanjem koncentracije nečistoća nastalih usled fotooksidacije. Intenzitet fotoluminescencije opadne na polovinu svoje početne vrednosti u slučaju kada je 0.4 % nečistoća prisutno u filmu. U tom slučaju je srednje rastojanje između nečistoća (akceptora) šest puta veće od srednjeg rastojanja između TPD molekula (donora). Direktan dugodometni Forsterov transfer energije je odbačen kao mehanizam gašenja fotoluminescencije jer je spektralno preklapanje emisije donora i apsorpcije akceptora zanemarljivo. Iz ovog razloga je postulirana ekscitonska difuzija u TPD filmovima, analogno nalazima u postojećoj literaturi. Prisustvo produkata oksidacije je potvrđeno uz pomoć infracrvene (IR) spektroskopije. Takodje, izračunat je IR spektar koristeći teoriju funkcionala gustine (DFT) i dobijeno je dobro slaganje sa eksperimentalnim rezultatima., The mechanism of photoluminescence (PL) quenching of thin amorphous N,N′-bis(3-methylphenyl)- N,N′-bis(phenyl)benzidine (TPD) films exposed to UV light in air is studied. TPD is small organic molecule widely used in production of organic light emmiting devices (OLEDs). Photoluminescence of TPD films decays exponentially with time of irradiation, i.e. with the increase of concentration of impurities (photo-oxidized TPD molecules) generated by UV irradiation in air. Intensity of PL decreases to half of its original value when the concentration of impurities reaches 0.4%. Average distance between impurities (acceptors) is almost an order of magnitude larger than average distance between host TPD molecules (donors). Direct long range Förster energy transfer is ruled out as the mechanism of PL quenching, as the overlap between donor and acceptor is lacking, and exciton self-diffusion in TPD films is postulated for the mechanism. The presence of oxidation products is confirmed by infrared (IR) spectroscopy. Vibrational spectra of TPD molecule and few other possible products of photo-oxidation of TPD molecule, obtained by density functional theory, are compared to experimental IR spectra.",
publisher = "Savez inženjera i tehničara Srbije, Beograd",
journal = "TEHNIKA",
title = "Mehanizam gašenja fotoluminescencije u tankim filmovima N,N′-bis(3- methylphenyl)-N,N′-bis(phenyl)benzidine osvetljenih UV svetlošću u vazduhu, MECHANISM OF PHOTOLUMINESCENCE QUENCHING IN THIN FILMS OF N,N′-BIS(3- METHYLPHENYL)-N,N′-BIS(PHENYL)BENZIDINE IRRADIATED BY UV LIGHT IN AIR",
pages = "914-909",
number = "6",
volume = "70",
doi = "10.5937/tehnika1506909T"
}

Tomović, A., Jovanović, V. P., Djurišić, I., PEJIĆ, M. M., Cerovski, V., BLESIĆ, S. M.,& Žikić, R.. (2015). Mehanizam gašenja fotoluminescencije u tankim filmovima N,N′-bis(3- methylphenyl)-N,N′-bis(phenyl)benzidine osvetljenih UV svetlošću u vazduhu. in TEHNIKA
Savez inženjera i tehničara Srbije, Beograd., 70(6), 909-914.
https://doi.org/10.5937/tehnika1506909T

Tomović A, Jovanović VP, Djurišić I, PEJIĆ MM, Cerovski V, BLESIĆ SM, Žikić R. Mehanizam gašenja fotoluminescencije u tankim filmovima N,N′-bis(3- methylphenyl)-N,N′-bis(phenyl)benzidine osvetljenih UV svetlošću u vazduhu. in TEHNIKA. 2015;70(6):909-914.
doi:10.5937/tehnika1506909T .

Tomović, Aleksandar, Jovanović, Vladimir P., Djurišić, Ivana, PEJIĆ, MILAN M., Cerovski, Viktor, BLESIĆ, SUZANA M., Žikić, Radomir, "Mehanizam gašenja fotoluminescencije u tankim filmovima N,N′-bis(3- methylphenyl)-N,N′-bis(phenyl)benzidine osvetljenih UV svetlošću u vazduhu" in TEHNIKA, 70, no. 6 (2015):909-914,
https://doi.org/10.5937/tehnika1506909T . .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Djurišić, Ivana
AU  - Cerovski, Viktor
AU  - Nastasijević, Branislav
AU  - Veielović, S. R.
AU  - Radulović, K.
AU  - Žikić, Radomir
PY  - 2015
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/876
AB  - The photoluminescence (PL) quenching mechanism of UV light and air-exposed amorphous thin films of 4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl (DPVBi), a well-known hole-transport material used in organic light-emitting diodes, is studied. Thin films of DPVBi are stable when exposed to UV light in vacuum but tend to degrade if oxygen is present simultaneously. This is evident from the changes in UV-vis absorption spectra of the latter, showing that degradation rate of DPVBi films is linearly proportional to both oxygen concentration and UV light intensity. Mass spectrometry study of such films revealed a number of different oxygen-containing molecules and fragments of DPVBi thus confirming apparent photo-oxidation process. Also, DFT study of molecular DPVBi with and without oxygen was carried out, the IR spectra calculated for the lowest energy molecules found and the results are compared with the experiment. The most sensitive to photo-oxidation is DPVBi photoluminescence, which decays exponentially with respect to the concentration of photo-oxidized DPVBi molecules (impurities). The PL quantum yield of DPVBi thin film drops to a half of its original value for 0.2% of the impurities present, at which point an average distance between DPVBi molecules (the donors) and photo-oxidized DPVBi species (acceptors) is an order of magnitude larger than the separation between two adjacent molecules. This implies a need for a long-range Forster energy transfer, which we rule out based on the lack of a donor-acceptor spectral overlap. The apparent discrepancy can be removed by postulating exciton self-diffusion in DPVBi thin films, for which there is supporting evidence in existing literature.
PB  - Elsevier, Amsterdam
T2  - Journal of Luminescence
T1  - Fast photoluminescence quenching in thin films of 4,4 '-bis(2,2-diphenylvinyl)-1,1 '-biphenyl exposed to air
EP  - 210
SP  - 204
VL  - 167
DO  - 10.1016/j.jlumin.2015.06.036
ER  - 

@article{
author = "Tomović, Aleksandar and Jovanović, Vladimir P. and Djurišić, Ivana and Cerovski, Viktor and Nastasijević, Branislav and Veielović, S. R. and Radulović, K. and Žikić, Radomir",
year = "2015",
abstract = "The photoluminescence (PL) quenching mechanism of UV light and air-exposed amorphous thin films of 4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl (DPVBi), a well-known hole-transport material used in organic light-emitting diodes, is studied. Thin films of DPVBi are stable when exposed to UV light in vacuum but tend to degrade if oxygen is present simultaneously. This is evident from the changes in UV-vis absorption spectra of the latter, showing that degradation rate of DPVBi films is linearly proportional to both oxygen concentration and UV light intensity. Mass spectrometry study of such films revealed a number of different oxygen-containing molecules and fragments of DPVBi thus confirming apparent photo-oxidation process. Also, DFT study of molecular DPVBi with and without oxygen was carried out, the IR spectra calculated for the lowest energy molecules found and the results are compared with the experiment. The most sensitive to photo-oxidation is DPVBi photoluminescence, which decays exponentially with respect to the concentration of photo-oxidized DPVBi molecules (impurities). The PL quantum yield of DPVBi thin film drops to a half of its original value for 0.2% of the impurities present, at which point an average distance between DPVBi molecules (the donors) and photo-oxidized DPVBi species (acceptors) is an order of magnitude larger than the separation between two adjacent molecules. This implies a need for a long-range Forster energy transfer, which we rule out based on the lack of a donor-acceptor spectral overlap. The apparent discrepancy can be removed by postulating exciton self-diffusion in DPVBi thin films, for which there is supporting evidence in existing literature.",
publisher = "Elsevier, Amsterdam",
journal = "Journal of Luminescence",
title = "Fast photoluminescence quenching in thin films of 4,4 '-bis(2,2-diphenylvinyl)-1,1 '-biphenyl exposed to air",
pages = "210-204",
volume = "167",
doi = "10.1016/j.jlumin.2015.06.036"
}

Tomović, A., Jovanović, V. P., Djurišić, I., Cerovski, V., Nastasijević, B., Veielović, S. R., Radulović, K.,& Žikić, R.. (2015). Fast photoluminescence quenching in thin films of 4,4 '-bis(2,2-diphenylvinyl)-1,1 '-biphenyl exposed to air. in Journal of Luminescence
Elsevier, Amsterdam., 167, 204-210.
https://doi.org/10.1016/j.jlumin.2015.06.036

Tomović A, Jovanović VP, Djurišić I, Cerovski V, Nastasijević B, Veielović SR, Radulović K, Žikić R. Fast photoluminescence quenching in thin films of 4,4 '-bis(2,2-diphenylvinyl)-1,1 '-biphenyl exposed to air. in Journal of Luminescence. 2015;167:204-210.
doi:10.1016/j.jlumin.2015.06.036 .

Tomović, Aleksandar, Jovanović, Vladimir P., Djurišić, Ivana, Cerovski, Viktor, Nastasijević, Branislav, Veielović, S. R., Radulović, K., Žikić, Radomir, "Fast photoluminescence quenching in thin films of 4,4 '-bis(2,2-diphenylvinyl)-1,1 '-biphenyl exposed to air" in Journal of Luminescence, 167 (2015):204-210,
https://doi.org/10.1016/j.jlumin.2015.06.036 . .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Djurišić, Ivana
AU  - Cerovski, Viktor
AU  - Nastasijević, Branislav
AU  - Veličković, Suzana
AU  - Radulović, Katarina
AU  - Žikić, Radomir
AU  - Srdanov, Vojislav I.
PY  - 2014
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1902
AB  - We studied degradation of 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl (DPVBi), well know OLED material. Thermally evaporated thin films of DPVBi were irradiated with UV light in ambient, vacuum and under different oxygen pressures. The cause of degradation is reaction between UV excited DPVBi molecules and oxygen, via formation of singlet oxygen or electron transfer from excited DPVBi to molecular oxygen. Reaction rates depend on oxygen concentration and UV light intensity. These reactions lead to formation of oxidized species as evidenced by ASAP and MALDI-TOF mass spectroscopy. Photoluminescence quenching has two parts. One part is reversible and may imply formation of charge transfer complexes and the other is irreversible, caused by formation of oxidized species. IR and absorption spectra are studied by Density Functional Theory and results compared with the experiment.
PB  - Materials Research Society of Serbia
T2  - THE SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Programme and The Book of Abstracts
T1  - Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light
SP  - 100
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_1902
ER  - 

@article{
author = "Tomović, Aleksandar and Jovanović, Vladimir P. and Djurišić, Ivana and Cerovski, Viktor and Nastasijević, Branislav and Veličković, Suzana and Radulović, Katarina and Žikić, Radomir and Srdanov, Vojislav I.",
year = "2014",
abstract = "We studied degradation of 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl (DPVBi), well know OLED material. Thermally evaporated thin films of DPVBi were irradiated with UV light in ambient, vacuum and under different oxygen pressures. The cause of degradation is reaction between UV excited DPVBi molecules and oxygen, via formation of singlet oxygen or electron transfer from excited DPVBi to molecular oxygen. Reaction rates depend on oxygen concentration and UV light intensity. These reactions lead to formation of oxidized species as evidenced by ASAP and MALDI-TOF mass spectroscopy. Photoluminescence quenching has two parts. One part is reversible and may imply formation of charge transfer complexes and the other is irreversible, caused by formation of oxidized species. IR and absorption spectra are studied by Density Functional Theory and results compared with the experiment.",
publisher = "Materials Research Society of Serbia",
journal = "THE SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Programme and The Book of Abstracts",
title = "Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light",
pages = "100",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_1902"
}

Tomović, A., Jovanović, V. P., Djurišić, I., Cerovski, V., Nastasijević, B., Veličković, S., Radulović, K., Žikić, R.,& Srdanov, V. I.. (2014). Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light. in THE SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Programme and The Book of Abstracts
Materials Research Society of Serbia., 100.
https://hdl.handle.net/21.15107/rcub_rimsi_1902

Tomović A, Jovanović VP, Djurišić I, Cerovski V, Nastasijević B, Veličković S, Radulović K, Žikić R, Srdanov VI. Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light. in THE SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Programme and The Book of Abstracts. 2014;:100.
https://hdl.handle.net/21.15107/rcub_rimsi_1902 .

Tomović, Aleksandar, Jovanović, Vladimir P., Djurišić, Ivana, Cerovski, Viktor, Nastasijević, Branislav, Veličković, Suzana, Radulović, Katarina, Žikić, Radomir, Srdanov, Vojislav I., "Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light" in THE SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Programme and The Book of Abstracts (2014):100,
https://hdl.handle.net/21.15107/rcub_rimsi_1902 .

TY  - CONF
AU  - Nastasijević, Branislav
AU  - Tomović, Aleksandar
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
AU  - Veličković, Suzana
PY  - 2014
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1897
AB  - An Atmospheric pressure Solids Analysis Probe (ASAP) mass spectrometer are used for investigation the ionization mechanism and fragmentation pathways of 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl (DPVBi). DPVBi is material used in OLEDs (organic light-emitting diode). Results obtained indicate that by controlling ion source conditions it is possible to optimize forming of desired precursor ion, primarily radical cation and in less content protonated ion of DPVBi. The results presented illustrate the usefulness of ASAP MS in the characterization of DPVBi compounds.
PB  - Society of Physical Chemists of Serbia
C3  - PHYSICAL CHEMISTRY 2014 (Proceedings, Volume III)
T1  - ANALYSIS OF 4,4′-BIS(2,2′DIPHENYL VINYL)-1,1′- BIPHENYL USING THE ATMOSPHERIC-PRESSURE SOLIDS ANALYSIS PROBE FOR IONIZATION
EP  - 1066
SP  - 1063
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_1897
ER  - 

@conference{
author = "Nastasijević, Branislav and Tomović, Aleksandar and Jovanović, Vladimir P. and Žikić, Radomir and Veličković, Suzana",
year = "2014",
abstract = "An Atmospheric pressure Solids Analysis Probe (ASAP) mass spectrometer are used for investigation the ionization mechanism and fragmentation pathways of 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl (DPVBi). DPVBi is material used in OLEDs (organic light-emitting diode). Results obtained indicate that by controlling ion source conditions it is possible to optimize forming of desired precursor ion, primarily radical cation and in less content protonated ion of DPVBi. The results presented illustrate the usefulness of ASAP MS in the characterization of DPVBi compounds.",
publisher = "Society of Physical Chemists of Serbia",
journal = "PHYSICAL CHEMISTRY 2014 (Proceedings, Volume III)",
title = "ANALYSIS OF 4,4′-BIS(2,2′DIPHENYL VINYL)-1,1′- BIPHENYL USING THE ATMOSPHERIC-PRESSURE SOLIDS ANALYSIS PROBE FOR IONIZATION",
pages = "1066-1063",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_1897"
}

Nastasijević, B., Tomović, A., Jovanović, V. P., Žikić, R.,& Veličković, S.. (2014). ANALYSIS OF 4,4′-BIS(2,2′DIPHENYL VINYL)-1,1′- BIPHENYL USING THE ATMOSPHERIC-PRESSURE SOLIDS ANALYSIS PROBE FOR IONIZATION. in PHYSICAL CHEMISTRY 2014 (Proceedings, Volume III)
Society of Physical Chemists of Serbia., 1063-1066.
https://hdl.handle.net/21.15107/rcub_rimsi_1897

Nastasijević B, Tomović A, Jovanović VP, Žikić R, Veličković S. ANALYSIS OF 4,4′-BIS(2,2′DIPHENYL VINYL)-1,1′- BIPHENYL USING THE ATMOSPHERIC-PRESSURE SOLIDS ANALYSIS PROBE FOR IONIZATION. in PHYSICAL CHEMISTRY 2014 (Proceedings, Volume III). 2014;:1063-1066.
https://hdl.handle.net/21.15107/rcub_rimsi_1897 .

Nastasijević, Branislav, Tomović, Aleksandar, Jovanović, Vladimir P., Žikić, Radomir, Veličković, Suzana, "ANALYSIS OF 4,4′-BIS(2,2′DIPHENYL VINYL)-1,1′- BIPHENYL USING THE ATMOSPHERIC-PRESSURE SOLIDS ANALYSIS PROBE FOR IONIZATION" in PHYSICAL CHEMISTRY 2014 (Proceedings, Volume III) (2014):1063-1066,
https://hdl.handle.net/21.15107/rcub_rimsi_1897 .

TY  - JOUR
AU  - Tomović, Aleksandar
AU  - Markesević, N.
AU  - Scarpellini, M.
AU  - Bovio, S.
AU  - Lucenti, E.
AU  - Milani, P.
AU  - Žikić, Radomir
AU  - Jovanović, Vladimir P.
AU  - Srdanov, V. I.
PY  - 2014
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/812
AB  - Owing to their low glass transition temperature, T-g, amorphous thin films of N,N'-bis(3-methylphenyl)-N,N'bis(phenyl)benzidine (TPD) undergo morphological changes even at room temperature. It has been noticed previously that exposure to UV light can increase apparent T-g of TPD films and thus stabilize their morphology. However, the reason behind increase in structural stability was not examined at the time. Here we present evidence that TPD molecules undergo photo-oxidation in air when exposed to lambda approximate to 350 nm radiation and that less than 5% of the photo-oxidized species are needed to prevent dewetting of thin TPD films. We propose that photo-oxidized TPD species bind strongly to both ordinary TPD molecules and to terminal hydroxyl groups at the substrate surface, which decreases mobility of TPD molecules and makes thin TPD film less prone to morphology changes.
PB  - Elsevier Science Sa, Lausanne
T2  - Thin Solid Films
T1  - Stabilization of N,N '-bis(3-methylphenyl)-N,N '-bis(phenyl)benzidine thin film morphology with UV light
EP  - 103
SP  - 99
VL  - 562
DO  - 10.1016/j.tsf.2014.03.081
ER  - 

@article{
author = "Tomović, Aleksandar and Markesević, N. and Scarpellini, M. and Bovio, S. and Lucenti, E. and Milani, P. and Žikić, Radomir and Jovanović, Vladimir P. and Srdanov, V. I.",
year = "2014",
abstract = "Owing to their low glass transition temperature, T-g, amorphous thin films of N,N'-bis(3-methylphenyl)-N,N'bis(phenyl)benzidine (TPD) undergo morphological changes even at room temperature. It has been noticed previously that exposure to UV light can increase apparent T-g of TPD films and thus stabilize their morphology. However, the reason behind increase in structural stability was not examined at the time. Here we present evidence that TPD molecules undergo photo-oxidation in air when exposed to lambda approximate to 350 nm radiation and that less than 5% of the photo-oxidized species are needed to prevent dewetting of thin TPD films. We propose that photo-oxidized TPD species bind strongly to both ordinary TPD molecules and to terminal hydroxyl groups at the substrate surface, which decreases mobility of TPD molecules and makes thin TPD film less prone to morphology changes.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Thin Solid Films",
title = "Stabilization of N,N '-bis(3-methylphenyl)-N,N '-bis(phenyl)benzidine thin film morphology with UV light",
pages = "103-99",
volume = "562",
doi = "10.1016/j.tsf.2014.03.081"
}

Tomović, A., Markesević, N., Scarpellini, M., Bovio, S., Lucenti, E., Milani, P., Žikić, R., Jovanović, V. P.,& Srdanov, V. I.. (2014). Stabilization of N,N '-bis(3-methylphenyl)-N,N '-bis(phenyl)benzidine thin film morphology with UV light. in Thin Solid Films
Elsevier Science Sa, Lausanne., 562, 99-103.
https://doi.org/10.1016/j.tsf.2014.03.081

Tomović A, Markesević N, Scarpellini M, Bovio S, Lucenti E, Milani P, Žikić R, Jovanović VP, Srdanov VI. Stabilization of N,N '-bis(3-methylphenyl)-N,N '-bis(phenyl)benzidine thin film morphology with UV light. in Thin Solid Films. 2014;562:99-103.
doi:10.1016/j.tsf.2014.03.081 .

Tomović, Aleksandar, Markesević, N., Scarpellini, M., Bovio, S., Lucenti, E., Milani, P., Žikić, Radomir, Jovanović, Vladimir P., Srdanov, V. I., "Stabilization of N,N '-bis(3-methylphenyl)-N,N '-bis(phenyl)benzidine thin film morphology with UV light" in Thin Solid Films, 562 (2014):99-103,
https://doi.org/10.1016/j.tsf.2014.03.081 . .

TY  - GEN
AU  - Jovanović, Vladimir P.
AU  - Li, Z.Z.
AU  - Raffy, H.
PY  - 2014
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2159
AB  - An important, still open question in solid state physics is the mechanism of high-temperature superconductivity observed in cuprate compounds, discovered 28 years ago. They are characterized by a layered structure - superconducting CuO2 planes separated by doping layers. Superconductivity emerges from an insulating antiferromagnetic state by doping the CuO2 planes with holes or electrons. Structurally, the simplest cuprate family is only composed of CuO2 planes separated by Sr planes and it might be considered as a model cuprate. However, it appeared that such compound is difficult to prepare: no single crystals were produced to date. Ceramic samples are prepared under high pressure. Epitaxial films are also difficult to synthesize. We have studied Sr1-xLaxCuOδ (SLCO) compound which is electron-doped by partial substitution Sr2+/La3+. As most of research is focused on hole-doped cuprates, our goal was to make stable superconducting SLCO thin films to perform the first measurements of magnetic and electrical transport properties of this "model" cuprate family. C-axis oriented films were deposited by rf magnetron sputtering technique on heated substrates suitable for epitaxial growth. We determined basic superconducting properties of these films, namely the critical temperature and upper critical fields, and the temperature and field dependence of the critical currents. Normal state transport properties were also investigated. In particular a strong temperature dependence of the Hall number was observed, with a change of sign., indicating that two types of carriers are present. Negative in-plane magnetoresistance was also detected, indicative of some remaining antiferromagnetism. Any theory that concerns the mechanism of superconductivity of cuprates must be able to explain these properties.
PB  - Serbian Ceramic Society
T2  - 3rd Serbian Ceramic Society Conference “Advanced ceramics and applications” – ACA III, Belgrade
T1  - Transport Properties of Electron-doped Sr1-xLaxCuOδ Superconducting Thin Films
SP  - 43
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2159
ER  - 

@misc{
author = "Jovanović, Vladimir P. and Li, Z.Z. and Raffy, H.",
year = "2014",
abstract = "An important, still open question in solid state physics is the mechanism of high-temperature superconductivity observed in cuprate compounds, discovered 28 years ago. They are characterized by a layered structure - superconducting CuO2 planes separated by doping layers. Superconductivity emerges from an insulating antiferromagnetic state by doping the CuO2 planes with holes or electrons. Structurally, the simplest cuprate family is only composed of CuO2 planes separated by Sr planes and it might be considered as a model cuprate. However, it appeared that such compound is difficult to prepare: no single crystals were produced to date. Ceramic samples are prepared under high pressure. Epitaxial films are also difficult to synthesize. We have studied Sr1-xLaxCuOδ (SLCO) compound which is electron-doped by partial substitution Sr2+/La3+. As most of research is focused on hole-doped cuprates, our goal was to make stable superconducting SLCO thin films to perform the first measurements of magnetic and electrical transport properties of this "model" cuprate family. C-axis oriented films were deposited by rf magnetron sputtering technique on heated substrates suitable for epitaxial growth. We determined basic superconducting properties of these films, namely the critical temperature and upper critical fields, and the temperature and field dependence of the critical currents. Normal state transport properties were also investigated. In particular a strong temperature dependence of the Hall number was observed, with a change of sign., indicating that two types of carriers are present. Negative in-plane magnetoresistance was also detected, indicative of some remaining antiferromagnetism. Any theory that concerns the mechanism of superconductivity of cuprates must be able to explain these properties.",
publisher = "Serbian Ceramic Society",
journal = "3rd Serbian Ceramic Society Conference “Advanced ceramics and applications” – ACA III, Belgrade",
title = "Transport Properties of Electron-doped Sr1-xLaxCuOδ Superconducting Thin Films",
pages = "43",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2159"
}

Jovanović, V. P., Li, Z.Z.,& Raffy, H.. (2014). Transport Properties of Electron-doped Sr1-xLaxCuOδ Superconducting Thin Films. in 3rd Serbian Ceramic Society Conference “Advanced ceramics and applications” – ACA III, Belgrade
Serbian Ceramic Society., 43.
https://hdl.handle.net/21.15107/rcub_rimsi_2159

Jovanović VP, Li Z, Raffy H. Transport Properties of Electron-doped Sr1-xLaxCuOδ Superconducting Thin Films. in 3rd Serbian Ceramic Society Conference “Advanced ceramics and applications” – ACA III, Belgrade. 2014;:43.
https://hdl.handle.net/21.15107/rcub_rimsi_2159 .

Jovanović, Vladimir P., Li, Z.Z., Raffy, H., "Transport Properties of Electron-doped Sr1-xLaxCuOδ Superconducting Thin Films" in 3rd Serbian Ceramic Society Conference “Advanced ceramics and applications” – ACA III, Belgrade (2014):43,
https://hdl.handle.net/21.15107/rcub_rimsi_2159 .

TY  - CONF
AU  - Tomović, Aleksandar
AU  - Markesevic, Nemanja
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
AU  - Scarpellini, M.
AU  - Lucenti, E.
AU  - Milani, P.
AU  - Srdanov, V. I.
PY  - 2013
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2167
AB  - Triphenyldiamine (TPD) or N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzdine is a well known hole-transporting material often used in electroluminescent devices. In bulk material glass transition temperature TTPDg ~ 60°C [1] is rather low and for sufficiently thin films (thickness d ~ 30 nm) deposited on a fused-silica substrate, dewetting occurs even at room temperature [2]. Morphological changes, which are often related to low Tg, lead to degradation of device performance in which thin film s are incorporated. That is why it is interesting to find a way to stabilize thin films. Following a brief report [3] on increased stability of UV irradiated TPD films, we focused on elucidating the underlying mechanism, since an explanation of chemical changes on molecular level has not yet been given. Thin amorphous TPD films were produced in physical vapor deposition (PVO) process on a fused silica or glass substrates. Immediately after evaporation one half of each sample was exposed to UV light under ambient conditions in order to compare effects of irradiation on a single film. Illuminated and non-illuminated areas of films are characterized using UV-visible spectroscopy and atomic force microscopy (AFM). Decrease in absorption bands intensity was observed after irradiation, indicating a chemical change in the sample. AFM study clearly shows that dewetting process at room temperature is stopped for irradiated samples thinner than 30nm. Illuminated samples remained stable even after few weeks of storage under ambient conditions and after 24h exposure to temperatures T > TTPDg. From proton nuclear magnetic resonance and mass spectrometry measurements, we find that photo-excited TPD reacts with oxygen from air, which leads to oxidation and hydroxylation of small amount of TPD molecules. W e conclude that increased thermal stability of irradiated
films is due to hydrogen bonding among TPD molecules and molecules formed in hydroxylation process.
PB  - Fakultet tehničkih nauka, Novi Sad
C3  - APOSTILLE workshop 02: Printed, flexible and nano electronics, Novi Sad
T1  - Towards the mechanisam of stabilization of TPD thin films with UV light
SP  - 23
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2167
ER  - 

@conference{
author = "Tomović, Aleksandar and Markesevic, Nemanja and Jovanović, Vladimir P. and Žikić, Radomir and Scarpellini, M. and Lucenti, E. and Milani, P. and Srdanov, V. I.",
year = "2013",
abstract = "Triphenyldiamine (TPD) or N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzdine is a well known hole-transporting material often used in electroluminescent devices. In bulk material glass transition temperature TTPDg ~ 60°C [1] is rather low and for sufficiently thin films (thickness d ~ 30 nm) deposited on a fused-silica substrate, dewetting occurs even at room temperature [2]. Morphological changes, which are often related to low Tg, lead to degradation of device performance in which thin film s are incorporated. That is why it is interesting to find a way to stabilize thin films. Following a brief report [3] on increased stability of UV irradiated TPD films, we focused on elucidating the underlying mechanism, since an explanation of chemical changes on molecular level has not yet been given. Thin amorphous TPD films were produced in physical vapor deposition (PVO) process on a fused silica or glass substrates. Immediately after evaporation one half of each sample was exposed to UV light under ambient conditions in order to compare effects of irradiation on a single film. Illuminated and non-illuminated areas of films are characterized using UV-visible spectroscopy and atomic force microscopy (AFM). Decrease in absorption bands intensity was observed after irradiation, indicating a chemical change in the sample. AFM study clearly shows that dewetting process at room temperature is stopped for irradiated samples thinner than 30nm. Illuminated samples remained stable even after few weeks of storage under ambient conditions and after 24h exposure to temperatures T > TTPDg. From proton nuclear magnetic resonance and mass spectrometry measurements, we find that photo-excited TPD reacts with oxygen from air, which leads to oxidation and hydroxylation of small amount of TPD molecules. W e conclude that increased thermal stability of irradiated
films is due to hydrogen bonding among TPD molecules and molecules formed in hydroxylation process.",
publisher = "Fakultet tehničkih nauka, Novi Sad",
journal = "APOSTILLE workshop 02: Printed, flexible and nano electronics, Novi Sad",
title = "Towards the mechanisam of stabilization of TPD thin films with UV light",
pages = "23",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2167"
}

Tomović, A., Markesevic, N., Jovanović, V. P., Žikić, R., Scarpellini, M., Lucenti, E., Milani, P.,& Srdanov, V. I.. (2013). Towards the mechanisam of stabilization of TPD thin films with UV light. in APOSTILLE workshop 02: Printed, flexible and nano electronics, Novi Sad
Fakultet tehničkih nauka, Novi Sad., 23.
https://hdl.handle.net/21.15107/rcub_rimsi_2167

Tomović A, Markesevic N, Jovanović VP, Žikić R, Scarpellini M, Lucenti E, Milani P, Srdanov VI. Towards the mechanisam of stabilization of TPD thin films with UV light. in APOSTILLE workshop 02: Printed, flexible and nano electronics, Novi Sad. 2013;:23.
https://hdl.handle.net/21.15107/rcub_rimsi_2167 .

Tomović, Aleksandar, Markesevic, Nemanja, Jovanović, Vladimir P., Žikić, Radomir, Scarpellini, M., Lucenti, E., Milani, P., Srdanov, V. I., "Towards the mechanisam of stabilization of TPD thin films with UV light" in APOSTILLE workshop 02: Printed, flexible and nano electronics, Novi Sad (2013):23,
https://hdl.handle.net/21.15107/rcub_rimsi_2167 .

TY  - CONF
AU  - Jovanović, Vladimir P.
AU  - Raffy, H.
AU  - Li, Z.Z.
AU  - Remenyi, G.
AU  - Monceau, P.
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2168
AB  - We studied the normal state magnetoresistance of underdoped superconducting epitaxial Sr1-xLaxCuO2 thin films by applying a high magnetic field up to 22 T parallel to the CuO2 planes and by varying the orientation of a field of given intensity in order to probe the underlying spin system. This infinite layer compound which has the simplest structure of all the cuprates presents a monotonic negative in-plane magnetoresistance with an anisotropic angular dependence which depends on the doping level [1] and on the field intensity [2]. Angular dependence of the in-plane magnetoresistance at highest magnetic fields is the same for films with different doping levels [2]. We compare our observations with the corresponding ones for the other electron-doped family Ln2-xCexCuO4 (Ln=Nd, Pr, La) and we attribute them to a manifestation of antiferromagnetism which appears to be only due to spins in the CuO2 planes.
PB  - Faculty of Physics, University of Belgrade
C3  - XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade
T1  - Magnetic Field Dependence Of Anisotropy Of In-plane Angular Magnetoresistance Of Electron-doped Sr1-xLaxCuO2 Thin Films
SP  - 66
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2168
ER  - 

@conference{
author = "Jovanović, Vladimir P. and Raffy, H. and Li, Z.Z. and Remenyi, G. and Monceau, P.",
year = "2011",
abstract = "We studied the normal state magnetoresistance of underdoped superconducting epitaxial Sr1-xLaxCuO2 thin films by applying a high magnetic field up to 22 T parallel to the CuO2 planes and by varying the orientation of a field of given intensity in order to probe the underlying spin system. This infinite layer compound which has the simplest structure of all the cuprates presents a monotonic negative in-plane magnetoresistance with an anisotropic angular dependence which depends on the doping level [1] and on the field intensity [2]. Angular dependence of the in-plane magnetoresistance at highest magnetic fields is the same for films with different doping levels [2]. We compare our observations with the corresponding ones for the other electron-doped family Ln2-xCexCuO4 (Ln=Nd, Pr, La) and we attribute them to a manifestation of antiferromagnetism which appears to be only due to spins in the CuO2 planes.",
publisher = "Faculty of Physics, University of Belgrade",
journal = "XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade",
title = "Magnetic Field Dependence Of Anisotropy Of In-plane Angular Magnetoresistance Of Electron-doped Sr1-xLaxCuO2 Thin Films",
pages = "66",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2168"
}

Jovanović, V. P., Raffy, H., Li, Z.Z., Remenyi, G.,& Monceau, P.. (2011). Magnetic Field Dependence Of Anisotropy Of In-plane Angular Magnetoresistance Of Electron-doped Sr1-xLaxCuO2 Thin Films. in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade
Faculty of Physics, University of Belgrade., 66.
https://hdl.handle.net/21.15107/rcub_rimsi_2168

Jovanović VP, Raffy H, Li Z, Remenyi G, Monceau P. Magnetic Field Dependence Of Anisotropy Of In-plane Angular Magnetoresistance Of Electron-doped Sr1-xLaxCuO2 Thin Films. in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade. 2011;:66.
https://hdl.handle.net/21.15107/rcub_rimsi_2168 .

Jovanović, Vladimir P., Raffy, H., Li, Z.Z., Remenyi, G., Monceau, P., "Magnetic Field Dependence Of Anisotropy Of In-plane Angular Magnetoresistance Of Electron-doped Sr1-xLaxCuO2 Thin Films" in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade (2011):66,
https://hdl.handle.net/21.15107/rcub_rimsi_2168 .

TY  - CONF
AU  - Markesevic, Nemanja
AU  - Jovanović, Vladimir P.
AU  - Žikić, Radomir
AU  - Scarpellini, M.
AU  - Lucenti, E.
AU  - Milani, P.
AU  - Srdanov, V. I.
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2163
AB  - N,N´-Bis(3-methylphenyl)-N,N’dyphenilbenzidine (TPD) is a hole-transport material used in
electroluminescent devices whose glass transition temperature, Tg, depends on the film thickness.[1] For sufficiently thin films (d<30 nm), dewetting of amorphous TPD films deposited on a on fused silica or an ITO substrate occurs even at room temperature.[2] Following a brief report on increased thermal stability of UV irradiated TPD films,[3] we investigated the underlying mechanism responsible for it. From proton NMR and mass spectrometry measurements, coupled with morphology (AFM) and spectroscopy (UV-VIS) studies, we find that photo-excited TPD species react with oxygen in air. This leads to partially oxidized TPD films whose increased thermal stability we ascribe to stronger hydrogen bonding of photo-oxidized TPD species with hydrophilic substrates.
PB  - Institute of physics, Pregrevica 118, Belgrade, Serbia
PB  - CIMAINA, Università di Milano, Via Celoria 16, 20133 Milano, Italy
PB  - 3 Institute for Terahertz Science and Technology, University of California Santa Barbara, Santa Barbara CA 93106
C3  - XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade
T1  - Altering Glass Transition of TPD thin Films with UV Light
SP  - 105
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2163
ER  - 

@conference{
author = "Markesevic, Nemanja and Jovanović, Vladimir P. and Žikić, Radomir and Scarpellini, M. and Lucenti, E. and Milani, P. and Srdanov, V. I.",
year = "2011",
abstract = "N,N´-Bis(3-methylphenyl)-N,N’dyphenilbenzidine (TPD) is a hole-transport material used in
electroluminescent devices whose glass transition temperature, Tg, depends on the film thickness.[1] For sufficiently thin films (d<30 nm), dewetting of amorphous TPD films deposited on a on fused silica or an ITO substrate occurs even at room temperature.[2] Following a brief report on increased thermal stability of UV irradiated TPD films,[3] we investigated the underlying mechanism responsible for it. From proton NMR and mass spectrometry measurements, coupled with morphology (AFM) and spectroscopy (UV-VIS) studies, we find that photo-excited TPD species react with oxygen in air. This leads to partially oxidized TPD films whose increased thermal stability we ascribe to stronger hydrogen bonding of photo-oxidized TPD species with hydrophilic substrates.",
publisher = "Institute of physics, Pregrevica 118, Belgrade, Serbia, CIMAINA, Università di Milano, Via Celoria 16, 20133 Milano, Italy, 3 Institute for Terahertz Science and Technology, University of California Santa Barbara, Santa Barbara CA 93106",
journal = "XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade",
title = "Altering Glass Transition of TPD thin Films with UV Light",
pages = "105",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2163"
}

Markesevic, N., Jovanović, V. P., Žikić, R., Scarpellini, M., Lucenti, E., Milani, P.,& Srdanov, V. I.. (2011). Altering Glass Transition of TPD thin Films with UV Light. in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade
Institute of physics, Pregrevica 118, Belgrade, Serbia., 105.
https://hdl.handle.net/21.15107/rcub_rimsi_2163

Markesevic N, Jovanović VP, Žikić R, Scarpellini M, Lucenti E, Milani P, Srdanov VI. Altering Glass Transition of TPD thin Films with UV Light. in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade. 2011;:105.
https://hdl.handle.net/21.15107/rcub_rimsi_2163 .

Markesevic, Nemanja, Jovanović, Vladimir P., Žikić, Radomir, Scarpellini, M., Lucenti, E., Milani, P., Srdanov, V. I., "Altering Glass Transition of TPD thin Films with UV Light" in XVIII Symposium on Condensed Matter Physics - SFKM 2011, Belgrade (2011):105,
https://hdl.handle.net/21.15107/rcub_rimsi_2163 .

TY  - JOUR
AU  - Jovanović, Vladimir P.
AU  - Li, ZZ
AU  - Raffy, H
PY  - 2011
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/504
AB  - We report a study on the superconducting properties of e-doped Sr0.88La0.12CuO2 (SLCO) thin films. SLCO has an infinite layer structure consisting of CuO2 planes, 3.40 angstrom apart, separated by Sr, La planes. Highly c-axis oriented thin films, with a critical temperature of 22-23 K, were epitaxially grown by sputtering. Their resistive transition hardly broadens under a perpendicular magnetic field, giving a narrow vortex liquid region. The critical current densities J(c) measured magnetically and by transport are in the 10(5)-10(6) A cm(-2) range at 4.2 K. The dependence of Jc on the orientation theta of the magnetic field, given by transport measurements, shows that, in contrast to highly anisotropic Bi2Sr2CaCu2Oy, there is no two-dimensional (2D) angular scaling: J(c)(theta, H) not equal J(c)(H-perpendicular to = H sin theta) and in parallel magnetic field Jc decreases with increasing fields. We also found an indication of a quasi-oscillatory behaviour of Jc(H-parallel to) possibly due to the successive entry of rows of vortices. In addition, the temperature dependence of the critical current is rather close to the behaviour derived from the Ginzburg-Landau theory. So, compared to BiSrCaCuO, this model cuprate appears to be much less anisotropic due to well coupled CuO2 planes and presents a more conventional behaviour.
PB  - IOP Publishing Ltd, Bristol
T2  - Superconductor Science & Technology
T1  - Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films
IS  - 5
VL  - 24
DO  - 10.1088/0953-2048/24/5/055002
ER  - 

@article{
author = "Jovanović, Vladimir P. and Li, ZZ and Raffy, H",
year = "2011",
abstract = "We report a study on the superconducting properties of e-doped Sr0.88La0.12CuO2 (SLCO) thin films. SLCO has an infinite layer structure consisting of CuO2 planes, 3.40 angstrom apart, separated by Sr, La planes. Highly c-axis oriented thin films, with a critical temperature of 22-23 K, were epitaxially grown by sputtering. Their resistive transition hardly broadens under a perpendicular magnetic field, giving a narrow vortex liquid region. The critical current densities J(c) measured magnetically and by transport are in the 10(5)-10(6) A cm(-2) range at 4.2 K. The dependence of Jc on the orientation theta of the magnetic field, given by transport measurements, shows that, in contrast to highly anisotropic Bi2Sr2CaCu2Oy, there is no two-dimensional (2D) angular scaling: J(c)(theta, H) not equal J(c)(H-perpendicular to = H sin theta) and in parallel magnetic field Jc decreases with increasing fields. We also found an indication of a quasi-oscillatory behaviour of Jc(H-parallel to) possibly due to the successive entry of rows of vortices. In addition, the temperature dependence of the critical current is rather close to the behaviour derived from the Ginzburg-Landau theory. So, compared to BiSrCaCuO, this model cuprate appears to be much less anisotropic due to well coupled CuO2 planes and presents a more conventional behaviour.",
publisher = "IOP Publishing Ltd, Bristol",
journal = "Superconductor Science & Technology",
title = "Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films",
number = "5",
volume = "24",
doi = "10.1088/0953-2048/24/5/055002"
}

Jovanović, V. P., Li, Z.,& Raffy, H.. (2011). Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films. in Superconductor Science & Technology
IOP Publishing Ltd, Bristol., 24(5).
https://doi.org/10.1088/0953-2048/24/5/055002

Jovanović VP, Li Z, Raffy H. Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films. in Superconductor Science & Technology. 2011;24(5).
doi:10.1088/0953-2048/24/5/055002 .

Jovanović, Vladimir P., Li, ZZ, Raffy, H, "Superconducting properties, anisotropy and critical currents of SrLaCuO e-doped epitaxial thin films" in Superconductor Science & Technology, 24, no. 5 (2011),
https://doi.org/10.1088/0953-2048/24/5/055002 . .

TY  - JOUR
AU  - Fruchter, L
AU  - Jovanović, Vladimir P.
AU  - Raffy, H
AU  - Labdi, Sid
AU  - Bouquet, F
AU  - Li, ZZ
PY  - 2010
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/432
AB  - The in-plane penetration depth of Sr0.88La0.12CuO2+x thin films at various doping obtained from oxygen reduction has been measured, using ac-susceptibility measurements. For the higher doping samples, the superfluid density deviates strongly from the s-wave behavior, suggesting, in analogy with other electron-doped cuprates, a contribution from a nodal hole pocket, or a small gap on the Fermi surface such as an anisotropic s-wave order parameter. The low value of the superfluid densities, likely due to a strong doping-induced disorder, places the superconducting transition of our samples in the phase-fluctuation regime.
PB  - Amer Physical Soc, College Pk
T2  - Physical Review B
T1  - Penetration depth of electron-doped infinite-layer Sr0.88La0.12CuO2+x thin films
IS  - 14
VL  - 82
DO  - 10.1103/PhysRevB.82.144529
ER  - 

@article{
author = "Fruchter, L and Jovanović, Vladimir P. and Raffy, H and Labdi, Sid and Bouquet, F and Li, ZZ",
year = "2010",
abstract = "The in-plane penetration depth of Sr0.88La0.12CuO2+x thin films at various doping obtained from oxygen reduction has been measured, using ac-susceptibility measurements. For the higher doping samples, the superfluid density deviates strongly from the s-wave behavior, suggesting, in analogy with other electron-doped cuprates, a contribution from a nodal hole pocket, or a small gap on the Fermi surface such as an anisotropic s-wave order parameter. The low value of the superfluid densities, likely due to a strong doping-induced disorder, places the superconducting transition of our samples in the phase-fluctuation regime.",
publisher = "Amer Physical Soc, College Pk",
journal = "Physical Review B",
title = "Penetration depth of electron-doped infinite-layer Sr0.88La0.12CuO2+x thin films",
number = "14",
volume = "82",
doi = "10.1103/PhysRevB.82.144529"
}

Fruchter, L., Jovanović, V. P., Raffy, H., Labdi, S., Bouquet, F.,& Li, Z.. (2010). Penetration depth of electron-doped infinite-layer Sr0.88La0.12CuO2+x thin films. in Physical Review B
Amer Physical Soc, College Pk., 82(14).
https://doi.org/10.1103/PhysRevB.82.144529

Fruchter L, Jovanović VP, Raffy H, Labdi S, Bouquet F, Li Z. Penetration depth of electron-doped infinite-layer Sr0.88La0.12CuO2+x thin films. in Physical Review B. 2010;82(14).
doi:10.1103/PhysRevB.82.144529 .

Fruchter, L, Jovanović, Vladimir P., Raffy, H, Labdi, Sid, Bouquet, F, Li, ZZ, "Penetration depth of electron-doped infinite-layer Sr0.88La0.12CuO2+x thin films" in Physical Review B, 82, no. 14 (2010),
https://doi.org/10.1103/PhysRevB.82.144529 . .