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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: ključnih besedah
Keywords: Charge transport, Organic semiconductors, Time of flight, Mobility, Traps
Published: 23.12.2016; Views: 3403; Downloads: 0
.pdf Fulltext (950,46 KB)

A pyrrolopyridazinedione-based copolymer for fullerene-free organic solar cells
Astrid-Caroline Knall, Samuel Rabensteiner, Sebastian F. Hoefler, Matiss Reinfelds, Mathias Hobisch, Heike M. A. Ehmann, Nadiia Pastukhova, Egon Pavlica, Gvido Bratina, Illie Hanzu, Shuguang Wen, Renqiang Yang, Gregor Trimmel, Thomas Rath, 2021, original scientific article

Abstract: The recent success of non-fullerene acceptors in organic photovoltaics also entails a change in the requirements to the polymer donor in terms of optical and morphological properties leading to a demand for novel conjugated polymers. Herein, we report on the synthesis of a 1,4-bis-(thiophene-2-yl)-pyrrolopyridazinedione based copolymer with 2-ethylhexyl substituents on the pyrrolopyridazinedione moiety. A 2D conjugated benzodithiophene (BDT) was chosen as comonomer. The resulting copolymer T-EHPPD-T-EHBDT showed a molecular weight of 10.2 kDa, an optical band gap of 1.79 eV, a hole mobility of 1.8 × 10−4 cm2 V−1 s−1 and a preferred face-on orientation with regard to the substrate. The comparably wide band gap as well as the determined energy levels (HOMO: −5.47 eV, LUMO: −3.68 eV) match well with the narrow band gap non-fullerene acceptor ITIC-F, which was used as the acceptor phase in the bulk heterojunction absorber layers in the investigated solar cells. The solar cells, prepared in inverted architecture, revealed power conversion efficiencies up to 7.4% using a donor:acceptor ratio of 1 : 1 in the absorber layer.
Found in: ključnih besedah
Summary of found: ...non-fullerene solar cells, charge transport, charge mobility, power conversion efficiency...
Keywords: non-fullerene solar cells, charge transport, charge mobility, power conversion efficiency
Published: 27.01.2021; Views: 629; Downloads: 0
.pdf Fulltext (2,68 MB)

Charge transport characterization of P3HT thin-film organic semiconductor
Matija Filipčič, 2021, research project (high school)

Abstract: The focus of this diploma seminar is to describe different types of charge transport theory and models used for finding mobility in semiconductors, more specifically focused on P3HT thin-film organic semiconductor. It also describes the time-of-flight method, which was used to measure the experimental data for P3HT with time dependent current I(t) curve. Another data set was obtained by performing Kinetic Monte Carlo (KMC) simulations using Miller-Abrahams hopping formalism. KMC was used to determine the material disorder, simulate I(t) curve and transit time for every charge carrier. Simulated data, different transit times and mobilities were then finally compared with experimental, in order to find agreements between the two.
Found in: ključnih besedah
Keywords: charge transport, P3HT, thin-film organic semiconductor
Published: 15.09.2021; Views: 143; Downloads: 0
.pdf Fulltext (590,08 KB)

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