Trimolecular recombination in polythiophene: fullerene bulk heterojunction solar cells

In this work, reduced Langevin recombination in poly(3-hexylthiophene): 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C-61 blends has been studied with various methods. Using photogenerated charge carrier extraction by linearly increasing voltage technique, it was observed that charge carrier recombination transient corresponds to trimolecular recombination. By double injection current transient technique, it was shown that the influence of deep charge carrier trapping is insignificant and that trimolecular recombination coefficient gamma is independent of the electric field. Finally, the temperature dependence of gamma was measured by integral time-of-flight method. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2996588]