%0 Journal Article
%A Kirchartz, T.
%A Pieters, B. E.
%A Kirkpatrick, J.
%A Rau, U.
%A Nelson, J.
%T Recombination via tail states in polythiophene:fullerene solar cells
%J Physical review / B
%V 83
%N 11
%@ 1098-0121
%C College Park, Md.
%I APS
%M PreJuSER-16868
%P 115209
%D 2011
%Z The authors would like to thank K. Taretto and M. Soldera (Uni. Neuquen) for discussion and inspiration in the early stage of the work and C. Shuttle (UCSB) and J. Durrant (Imperial College) for sharing the experimental data. In addition, we want to thank R. Mackenzie, G. Dibb, A. Maurano, and D. Credgington (Imperial College) for fruitful discussions on modeling and charge extraction. T. K. acknowledges partial support by an Imperial College Junior Research Fellowship. J. N. acknowledges the support of the UK Engineering and Physical Sciences Research Council through the Supergen (EP/031088/1) and Nanotechnology Grand Challenges (EP/F056710/1, EP/F056389/1) programmes.
%X State-of-the-art models used for drift-diffusion simulations of organic bulk heterojunction solar cells based on band transport are not capable of reproducing the voltage dependence of dark current density and carrier concentration of such devices, as determined by current-voltage and charge-extraction measurements. Here, we show how to correctly reproduce this experimental data by including an exponential tail of localized states into the density of states for both electrons and holes, and allowing recombination to occur between free charge carriers and charge carriers trapped in these states. When this recombination via tail states is included, the dependence of charge-carrier concentration on voltage is distinctly different from the case of band-to-band recombination and the dependence of recombination current on carrier concentration to a power higher than 2 can be explained.
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000288896400006
%R 10.1103/PhysRevB.83.115209
%U https://juser.fz-juelich.de/record/16868