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Ultra-visokovakuumski sistem za naparevanje organskih polprevodnikov
Robert Hudej, Gvido Bratina, 2001, original scientific article

Abstract: A new molecular-beam-epitaxy system for the growth of organic semiconductor layers was recently installed in the Laboratory for epitaxy and nanostructures of the Nova Gorica Polytechnic. The system is built around an ultra-high-vacuum chamber. The organic semiconductor material is evaporated from a low-temperature Knudsen cell. The system is equipped with a refraction high-energy electron-difraction system, a quadrupole mass spectrometer and a spectroscopic ellipsometer.
Found in: osebi
Keywords: ultra-high vacuum, molecular-beam epitaxy, Knudsen cell, mass quadrupole spectrometer, spectroscopic ellipsometer, high-energy electrons
Published: 10.07.2015; Views: 4204; Downloads: 18
URL Fulltext (0,00 KB)

Electrical conductivity in 3,4,9,10-perylenetetracarboxylic dianhidride (PTCDA)
Gvido Bratina, Robert Hudej, Marko Zavrtanik, John Nimly Brownell, 2001, original scientific article

Abstract: The transient photoresponse in 3,4,9,10-perylenetetracarboxylic dianhydride was examined in metal/organic semiconductor/metal heterostructures. Electron-hole pairs are generated within the structure for fields higher than 5 X 10[sup]4 V/cm as a consequence of the exciton dissociation. The mobility of the electrons perpendicular to the molecular layers increases with the applied electric field and saturates for fields higher than 5 X 10[sup]4 V/cm.
Found in: osebi
Keywords: organic semiconductor, thin films, transient photoconductivity
Published: 10.07.2015; Views: 4938; Downloads: 32
URL Fulltext (0,00 KB)

Highly active photocatalytic coatings prepared by a low-temperature method
Marko Kete, Gvido Bratina, Fernando Fresno, Urška Lavrenčič Štangar, Egon Pavlica, 2014, published scientific conference contribution

Found in: osebi
Keywords: fotokataliza, titanov dioksid, nanodelci, hidroksi tereftalna kislina
Published: 16.06.2016; Views: 4274; Downloads: 119
URL Fulltext (0,00 KB)

Flexible non-volatile optical memory thin-filmtransistor device with over 256 distinct levelsbased on an organic bicomponent blend
Gvido Bratina, Egon Pavlica, 2016, original scientific article

Abstract: Flexible non-volatile optical memory thin-filmtransistor device with over 256 distinct levelsbased on an organic bicomponent blendTim Leydecker1, Martin Herder2, Egon Pavlica3,GvidoBratina3,StefanHecht2*, Emanuele Orgiu1*and Paolo Samorì1*Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logiccircuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organicmemories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well asthe number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-filmtransistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromicdiarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bitstorage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses.We also report robustness over 70 write–erase cycles and non-volatility exceeding 500 days. The device was implementedon a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics andsmart nanodevices.
Found in: osebi
Keywords: organic semiconductors time of flight
Published: 22.06.2016; Views: 4302; Downloads: 0
.pdf Fulltext (2,78 MB)

A nanomesh scaffold for supramolecular nanowire optoelectronic devices
Lei Zhang, Egon Pavlica, Gvido Bratina, 2016, original scientific article

Abstract: Supramolecular organic nanowires are ideal nanostructures for optoelectronics because they exhibit both efficient exciton generation as a result of their high absorption coefficient and remarkable light sensitivity due to the low number of grain boundaries and high surface-to-volume ratio. To harvest photocurrent directly from supramolecular nanowires it is necessary to wire them up with nanoelectrodes that possess different work functions. However, devising strategies that can connect multiple nanowires at the same time has been challenging. Here, we report a general approach to simultaneously integrate hundreds of supramolecular nanowires of N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) in a hexagonal nanomesh scaffold with asymmetric nanoelectrodes. Optimized PTCDI-C8 nanowire photovoltaic devices exhibit a signal-to-noise ratio approaching 107, a photoresponse time as fast as 10 ns and an external quantum efficiency >55%. This nanomesh scaffold can also be used to investigate the fundamental mechanism of photoelectrical conversion in other low-dimensional semiconducting nanostructures.
Found in: osebi
Keywords: fotodetektor, organski polprevodnik, fotoprevodnost, organski kristal, elektronske komponente, nanožice
Published: 05.10.2016; Views: 4246; Downloads: 0
.pdf Fulltext (6,46 MB)

Interface-controlled growth of organic semiconductors on graphene
Jinta Mathews, Saim Emin, Egon Pavlica, Matjaž Valant, Gvido Bratina, 2017, original scientific article

Abstract: We have studied submonolayer coverages of N,N-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) on mechanically exfoliated graphene transferred onto SiO2 substrates. Our atomic force microscopy (AFM) data show that PDIF-CN2 forms irregularly-shaped 1.4 nm-high islands. From the selected area diffraction performed with transmission electron microscope (TEM) we conclude that this height corresponds to π−π stacks of molecules, which are inclined for 43° relative to the graphene surface. AFM also showed complete absence of PDIF-CN2 on single-layer graphene (SLG). Electric force microscopy revealed a marked difference in surface charge density between a single-layer graphene and bilayer graphene, with a higher surface charge on SLG than on the bilayer graphene. We associate this behavior with p− type doping of graphene due to the electrostatic dipole induced by the molecular water layer present at the graphene/SiO2 interface. The crucial role of the graphene/SiO2 interface in determining growth of PDIF-CN2 was further confirmed by TEM examination of PDIF-CN2 deposited onto unsupported SLG.
Found in: osebi
Keywords: afm, organic semiconductors, graphene
Published: 18.05.2017; Views: 3640; Downloads: 0
.pdf Fulltext (2,02 MB)

Negative field‐dependent charge mobility in crystalline organic semiconductors with delocalized transport
Andrey Kadashchuk, Egon Pavlica, Gvido Bratina, Fei Tong, 2018, original scientific article

Abstract: Charge-carrier mobility has been investigated by time-of-flight (TOF) transient photocurrent in a lateral transport con- figuration in highly crystalline thin films of 2,7-dioctyl[1]benzothieno [3,2-b][1] benzothiophene (C8-BTBT) grown by a zone-casting alignment technique. High TOF mobility has been revealed that it is consistent with the delocalized nature of the charge transport in this material, yet it featured a positive temperature dependence at T ≥ 295 K. Moreover, the mobility was surprisingly found to decrease with electric field in the high-temperature region. These observations are not compat- ible with the conventional band-transport mechanism. We have elaborated an analytic model based on effective-medium approximation to rationalize the puzzling findings. The model considers the delocalized charge transport within the energy landscape formed by long-range transport band-edge variations in imperfect organic crystalline materials and accounts for the field-dependent effective dimensionality of charge transport percolative paths. The results of the model calculations are found to be in good agreement with experimental data.
Found in: osebi
Keywords: time of flight, organic semiconductors, single crystals
Published: 07.05.2018; Views: 3446; Downloads: 0
.pdf Fulltext (2,01 MB)

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