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41.
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.
Keywords: fotodetektor, organski polprevodnik, fotoprevodnost, organski kristal, elektronske komponente, nanožice
Published in RUNG: 05.10.2016; Views: 5309; Downloads: 0
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42.
Pozabljeni zdravnik : Vloga dr. Karla Pečnika pri vprašanju slovenske gospodarske samostojnosti in vključevanja v mednarodno trgovino.
Rok Bratina, 2016, undergraduate thesis

Abstract: Diplomska naloga obravnava življenje in delo dr. Karla Pečnika, vsestransko izobraženega slovenskega izseljenca, ki je velik del svojega življenja preživel kot zdravnik jetičnih bolezni v Egiptu. Pričujoča naloga se osredotoča na Koroščevo brošuro Slovenci in mednarodni promet, ki jo je Pečnik napisal na podlagi večletnega preučevanja gospodarskega dogajanja v Egiptu. Ker je bil zelo dobro obveščen tudi o stanju v domovini, je s pomočjo goriškega politika Andreja Gabrščka leta 1898 izdal omenjeno brošuro v kateri je želel spodbuditi Slovence k bolj samostojnemu gospodarskemu delovanju, neodvisnemu od ostalih dežel v Habsburški monarhiji. Kot je zapisal Pečnik, je svetovna trgovina odpravila vse omejitve, ki bi lahko ovirale slovenske dežele na poti do gospodarske samostojnosti. Namen in cilj pričujoče diplomske naloge je bil predstaviti življenje in delo Karla Pečnika, ga ponovno obuditi v slovenski gospodarski zgodovini in ga v prihodnje predstavljati kot enega tistih posameznikov, ki so imeli eno pomembnejših vlog pri nadaljnjem razvoju slovenskega gospodarstva. Dokaz za to je danes moč najti v njegovi brošuri Slovenci in mednarodni promet.
Keywords: Habsburška monarhija, gospodarstvo, liberalizem, mednarodna trgovina, slovenske dežele, Egipt, Karol Pečnik.
Published in RUNG: 04.10.2016; Views: 5497; Downloads: 243
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43.
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.
Keywords: organic semiconductors time of flight
Published in RUNG: 22.06.2016; Views: 5498; Downloads: 0
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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.
Keywords: organic semiconductor, thin films, transient photoconductivity
Published in RUNG: 10.07.2015; Views: 6523; Downloads: 40
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49.
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.
Keywords: ultra-high vacuum, molecular-beam epitaxy, Knudsen cell, mass quadrupole spectrometer, spectroscopic ellipsometer, high-energy electrons
Published in RUNG: 10.07.2015; Views: 5231; Downloads: 28
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50.
Transport električnega naboja v organskih polprevodnikih, simulacija po metodi Monte Carlo
Robert Hudej, Gvido Bratina, Egon Pavlica, 2003, original scientific article

Abstract: The electric-charge transport in organic semiconductors is essentially different to the transport in ordered inorganic crystals. The reason is in thelocalization of the energy states, which act as charge-carrier transport channels between molecules. Consequently, the determination of the basic transport parameters in organic materials is inherently more involved than in their inorganic counterparts. The analytical methods that are used to describe charge transport in inorganic materials are unsuitable, since they are based on the extended electronic energy structure. We report here on the simulation of charge transport in organic semiconductor thin films. The simulation is based on the Monte Carlo method and describes the charge-carrier transport within the framework of carrier hopping between the sites. We employed a Gaussian energy distribution of the hopping sites with disorder elements. The degree of disorder is characterized by the width of the Gaussian distribution and is measured in eV units. The results of the transport simulation in 3,4,9,10-perylenedianhydride tetracarboxylic acid (PTCDA) show that the photogenerated charge-carrier current depends on the film thickness, temperature and disorder degree. The simulated photocurrents have the same amplitude in thick films as in the thin films, but the overall shape of the I(t) curve is more dispersive in thin films. The charge-carrier mobility decreases with the increasing degree of disorder at a given temperature. The simulation of the photogenerated positive charge carriers current matches with the time-of-flight experiment in a glass/ITO/PTCDA(600 nm)/In heterostructure at room temperature and an applied bias voltage of 8 V.
Keywords: neurejeni kristali, metoda Monte Carlo, organski polprevodniki, transport naboja, PTCDA, tranzientne meritve
Published in RUNG: 10.07.2015; Views: 5824; Downloads: 23
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