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

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 pi-linker substituted by 4',4 ''-dimethoxytriphenylamine donor groups are presented. The influence of increasing fused thiophene rings of pi-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 pi-linker, shows better hole mobility and higher thermal stability than the compounds that contain thiophene or thieno [3,2-b]thiophene pi-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 pi-linker, the perovskite solar cells based on it achieve higher J(sc), V-oc and FF values than the devices based on the other two compounds. These results indicate that the increasing fused thiophene rings of pi-linker in hole transporting materials can be helpful to develop efficient perovskite solar cells. (C) 2016 Elsevier Ltd. All rights reserved.