Influence of π-linker on triphenylamine-based hole transporting materials in perovskite solar cells

Abstract

In this work, three simple hole transporting materials containing a thiophene, thieno [3,2-b]thiophene (two fused thiophene rings) or a dithieno[3,2-b:2′,3'-d]thiophene (three fused thiophene rings) as π-linker substituted by 4′,4″-dimethoxytriphenylamine donor groups are presented. The influence of increasing fused thiophene rings of π-linker in new compounds on the photophysical, electrochemical, thermal properties, hole mobility and photovoltaic performance in perovskite solar cells are investigated. The compound, in which dithieno[3,2-b:2′,3'-d]thiophene act as π-linker, shows better hole mobility and higher thermal stability than the compounds that contain thiophene or thieno [3,2-b]thiophene π-linker. Due to the improved hole mobility and superior hole extraction ability of the compound which contains dithieno[3,2-b:2′,3'-d]thiophene π-linker, the perovskite solar cells based on it achieve higher Jsc, Voc and FF values than the devices based on the other two compounds. These results indicate that the increasing fused thiophene rings of π-linker in hole transporting materials can be helpful to develop efficient perovskite solar cells.