LAUSR

Here, we demonstrate a new fulleropyrrolidine electron acceptor coded as DIF-ful-C60, following a one-step synthetic protocol. The absorption spectrum of DIF-ful-C60 suggests broader absorption over PC61BM while the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the molecule are −5.32 and −3.60 eV, respectively. The solution processed bulk-heterojunction polymer solar cells fabricated using a blend of DIF-ful-C60 with PTB7 and PTB7-Th as electron donors show power conversion efficiencies (PCEs) of 6.8 and 8.6%, respectively, which is highest reported so far for fulleropyrrolidine type electron acceptors. In comparison, the control devices made from PTB7:PC61BM and PTB7-Th:PC61BM blends showed PCEs of 6.2 and 7.9%, respectively. The increase in efficiency of the devices based on DIF-ful-C60 is due to increase in the short circuit current as well as open circuit voltage of ca. 0.8 V.