Planar inverted perovskite solar cells based on the electron transport layer of PC61BM:ITIC

A small molecule 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (ITIC) was used as the additive for the electron transport layer (ETL) of phenyl-C61-butyric acid methyl ester (PC61BM) in planar inverted perovskite solar cells (PSCs) fabricated by the flash method. Due to the proper LUMO level and decent electrical conductivity of ITIC, the photovoltaic properties of planar inverted PSCs based on the smooth PC61BM:ITIC (2 wt%) ETL were promoted, and the power conversion efficiency (PCE) and the short-circuit current density (Jsc) of the devices were increased to 12.41% and 18.53 mA cm−2, respectively, which were 13.3% and 13.5% enhancements relative to those of the undoped control devices. Therefore, ITIC was a promising additive for PC61BM ETL in inverted PSCs and the photovoltaic properties of devices could be improved accordingly.