A ternary organic solar cell with 300 nm thick active layer shows over 14% efficiency

In order to meet the requirements for making organic solar cells (OSCs) through solution printing techniques, great efforts have been devoted into developing high performance OSCs with relatively thicker active layers. In this work, a thick-film (300 nm) ternary OSC with a power conversion efficiency of 14.3% is fabricated by introducing phenyl-C-61-butyric-acid-methyl ester (PC61BM) into a PBDB-T-2Cl:BTP-4F host blend. The addition of PC61BM is found to be helpful for improving the hole and electron mobilities, and thus facilitates charge transport as well as suppresses charge recombination in the active layers, leading to the improved efficiencies of OSCs with relatively thicker active layers. Our results demonstrate the feasibility of employing fullerene derivative PC61BM to construct a high-efficiency thick-film ternary device, which would promote the development of thick layer ternary OSCs to fulfill the requirements of future roll to roll production.