Effects of nematic liquid crystal additives on the performance of polymer solar cells

Nematic liquid crystals (NLCs), 4-cyano-4′-pentylbiphenyl and 4-cyano-4′-octylbiphenyl, were applied as additives to polymer solar cells with P3HT:PC₆₁BM 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 PC₆₁BM 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:PC₆₁BM 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 PC₆₁BM domains and enhanced hole/electron mobilities.