Highly Efficient PCDTBT:PC71 BM Based Photovoltaic Devices without Thermal Annealing Treatment

We propose an effective method to fabricate highly efficient organic photovoltaic cells based on poly [N-9-heptadecanyl-2, 7-carbazole-alt-5,5-(4'7'-di-2-thienyl-2'1'3-b-enzothiadiazole):[6,6]-phenyl C71-butyric acid methyl ester (PCDTBT:PC71BM). A power conversion efficiency of as high as 5.6% and a fill factor of 53.7% are achieved from the optimized cells. The influence of surface morphology of the active layer on the performance of the cells is also investigated.