A novel small molecule based on naphtho[1,2b:5,6-b0]dithiophene benefits both fullerene and non-fullerene solar cells

Abstract

Small molecule solar cells have made great progress in recent years. Herein, we synthesized a novel small molecule donor NDTR with naphtho[1,2-b:5,6-b0]dithiophene (NDT) units as the building blocks. NDTR exhibited complementary absorption for both fullerene acceptor PC71BM and non-fullerene acceptor IDIC. Meanwhile, NDTR possessed a HOMO energy level of 5.23 eV and a LUMO energy level of 3.50 eV, which matched well with these two kinds of acceptors. When mixed with PC71BM, a high power conversion efficiency (PCE) of 7.75% was obtained, while the NDTR:IDIC system presented a PCE of 6.60%. The results indicated that NDTR was an all-round small molecule donor which can work well in both fullerene and non-fullerene systems.