Enhancing the power conversion efficiency of PCDTBT:PC71BM polymer solar cells using a mixture of solvents

Organic polymer solar materials are shown to exhibit better solubility in mixed solvents than in pure ones, which affects the performance of their solar cells. In this article, poly[N-9-hepta-decanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole) (PCDTBT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) are used as active layer materials in solar cells. To optimize the performance of these active materials, the ratio of chloroform (CF) to chlorobenzene used as solvents to dissolve PCDTBT, and PC71BM is varied, which is shown to affect power conversion efficiency (PCE). The solar cell that shows the best performance with a PCE as high as 6.82 % is produced using a volume ratio of CF to chlorobenzene of 1:1.