Diarylmethanofullerene: Efficient Polymer Solar Cells with Low-Band- Gap Copolymer

Abstract

The photovoltaic performance of the polymer bulk heterojunction solar cells based on the low-band-gap D–A copolymer P as donor and modified fullerene (modi-PC60BM) as acceptor was in. We have achieved power conversion efficiency (PCE) of ∼2.35% for a polymer solar cell with modi-PC60BM as an electron acceptor in bulk heterojunction active layer, which is higher than that for PC60BM counterpart (1.50%). The increase in the PCE has been attributed to the increase in absorption in visible and higher LUMO level of modi-PC60BM, resulting in enhancement in Jsc and Voc, respectively. In the device fabrications, we studied the effect of the solvent additive and modified PEDOT:PSS as a hole transport layer. The PCE of the polymer solar cell was improved up to 3.63% when the P:modi-PC60BM active layer was processed with the addition of CN as an additive in the THF solution (CN/THF), which is mainly attributed to more balanced charge transport due to the increased crystallinity of P in the blend. The PCE of polymer ...