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Izboljšava izkoristka fotonapetostnega modula
Matej Boltar, 2012, undergraduate thesis

Found in: osebi
Keywords: fotovoltaika, fotonapetostne celice, fotonapetostni modul, fotonapetostna elektrarna, diplomske naloge
Published: 15.10.2013; Views: 2846; Downloads: 197
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Transient photocurrents in oligothiophene-based ultrathin film transistors
Egon Pavlica, Robert Hudej, Gvido Bratina, M. Leufgen, U. Bass, J. Geurts, L. W. Molenkamp, T. Muck, V. Wagner, 2004, published scientific conference contribution abstract

Found in: osebi
Published: 15.10.2013; Views: 2846; Downloads: 5
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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.
Found in: osebi
Keywords: neurejeni kristali, metoda Monte Carlo, organski polprevodniki, transport naboja, PTCDA, tranzientne meritve
Published: 10.07.2015; Views: 2192; Downloads: 5
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Vpliv dielektrika na delovanje organskega tankoplastnega tranzistorja: organski in anorganski dielektriki
Anže Peternel, 2015, undergraduate thesis

Abstract: Organski tankoplastni tranzistorji (OTFT) so polprevodniški elementi, ki opravljajo funkcijo stikal v elektronskih napravah. Med njihovo najpomembnejšo lastnost štejemo hitrost preklapljanja električnega toka. Hitrost preklapljanja je odvisna od mobilnosti nosilcev naboja, ta pa je odvisna predvsem od stične površine med plastjo dielektrika in polprevodnika. Preučili smo vpliv dielektrika na mobilnost vrzeli v OTFT-jih s polprevodnim polimerom poli(3-heksiltiofen) (P3HT). Primerjali smo dielektrike parilen C, termični oksid (SiO2) in oktadekiltriklorosilan (OTS). Ugotovili smo, da na mobilnost vrzeli močno vplivata hrapavost in polarnost dielektrika. Za najboljši dielektrik se je izkazal OTS, saj je bila mobilnost vrzeli najvišja glede na ostale preučene OTFT-je. Najvišja izmerjena mobilnost vrzeli je znašala 0.03 cm^2 V^−1 s^−1 . Pri OTFT-jih z dielektrikom OTS smo izmerili upor stika med elektrodama in plastjo polprevodnika. Upor je znašal 1 MΩ in predstavlja veliko oviro za tok, ki teče skozi OTFT. Iz pridobljenih rezultatov sklepamo, da so OTFT-ji z organskimi dielektriki boljši kot OTFT-ji z dielektrikom SiO2, če je njihova površina ravna in hidrofobna. Sklepamo da z optimizacijo upora stika med elektrodo in plastjo polprevodnika lahko pripravimo OTFT-je, ki so primerni za izdelavo fleksibilne organske elektronike.
Found in: osebi
Keywords: konjugirani polimeri, P3HT, termični oksid SiO2, parilen C, OTS, tokovno-napetostna karakteristika, mobilnost nosilcev naboja, pragovna napetost, upor stika kovina – polprevodnik
Published: 28.09.2015; Views: 3606; Downloads: 82
.pdf Fulltext (10,50 MB)

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: 1790; Downloads: 43
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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
Summary of found: organic bicomponent blendTim Leydecker1, Martin Herder2, Egon Pavlica3,GvidoBratina3,StefanHecht2*, Emanuele Orgiu1*and Paolo Samorì1*Organic...
Keywords: organic semiconductors time of flight
Published: 22.06.2016; Views: 2066; 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: 2078; Downloads: 0
.pdf Fulltext (6,46 MB)

The role of local potential minima on charge transport in thin organic semiconductor layers
Egon Pavlica, Raveendra Babu Penumala, Bratina Gvido, 2016, original scientific article

Abstract: We have performed a systematic study of dependence of time-resolved photocurrent on the point of charge excitation within the organic semiconductor channel formed by two coplanar metal electrodes. The results confirm that spatial variation of electric field between the electrodes crucially determines transport of photogenerated charge carriers through the organic layer. Time-of-flight measurements of photocurrent demonstrate that the transit time of photogenerated charge carrier packets drifting between the two electrodes decreases with increasing travelling distance. Such counterintuitive result cannot be reconciled with the spatial distribution of electric field between coplanar electrodes, alone. It is also in contrast to expected role of space-charge screening of external electric field. Supported by Monte Carlo simulations of hopping transport in disordered organic semiconductor layer, we submit that the space-charge screens the external electric field and captures slower charge carriers from the photogenerated charge carrier packet. The remaining faster carriers, exhibit velocity distribution with significantly higher mean value and shorter transit time.
Found in: osebi
Keywords: Charge transport, Organic semiconductors, Time of flight, Mobility, Traps
Published: 23.12.2016; Views: 1973; Downloads: 0
.pdf Fulltext (950,46 KB)

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