Effects of Nematic Liquid Crystal Additives on the Performance of Polymer Solar Cells

Abstract

Nematic liquid crystals (NLCs), 4-cyano-4′-pentylbiphenyl and 4-cyano-4′-octylbiphenyl, were applied as additives to polymer solar cells with P3HT:PC 61BM blend films. The incorporation of NLC additives led to a higher absorbance of the blend film, a higher crystallinity of P3HT, closer P3HT chains, larger PC 61BM domains and enhanced hole/electron mobilities even without post-thermal annealing. The non-annealed PSC with 4 wt.-% 8CB additives showed an increase in all parameters, resulting in a power conversion efficiency of 3.72% compared to 2.14% of the reference device without NLC additives. Nematic liquid crystals (NLCs) are applied as additives to polymer solar cells consisting of P3HT:PC 61BM blend films. The incorporation of NLC additives leads to a considerable improvement in power conversion efficiency even without post-thermal annealing, due to a higher absorbance of the blend film, a higher crystallinity of P3HT, closer P3HT chains, larger PC 61BM domains and enhanced hole/electron mobilities. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.