Mismatch of non-geminate recombination in polymer TQ1/fullerene blends employing different techniques

Abstract

The non-geminate recombination was investigated in TQ1:PC61BM:PC71BM (poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl]:[6,6]-Phenyl-C61-butyric-acid-methyl-ester:[6,6]-Phenyl-C71-butyric-acid-methyl-ester) bulk heterojunctions employing the extraction of the photogenerated charge carriers by linearly increasing voltage (photo-CELIV) and integral Time-of-Flight (ToF) techniques. The shapes of photo-CELIV and ToF transients point out purely non-reduced Langevin recombination while the decay of the photogenerated charge carrier density measured with photo-CELIV technique indicates reduced third-order recombination. A clear discrepancy could be explained by spatially separated holes and electrons during the delay time while employing photo-CELIV method.