Enhanced Efficiency of Planar Heterojunction Perovskite Solar Cells by a Light Soaking Treatment on Tris(pentafluorophenyl)borane-Doped Poly(triarylamine) Solution

This research used Lewis acid tris(pentafluorophenyl)borane (BCF) as a p-type dopant and a light soaking (LS) treatment to improve the conductivity of poly(triarylamine) (PTAA). Specifically, the conductivity of PTAA films was improved by two orders of magnitude using BCF as a p-type dopant, and the conductivity of BCF-doped PTAA films could be further improved by using the LS treatment on its solution. The working mechanism of the formation of frustrated Lewis pairs between BCF and PTAA was proposed to explain the BCF doping and LS treatment effects on the hole transport property of PTAA. When 5 min LS-PTAA films with 8 wt % BCF were used as the hole transport layer in pin planar heterojunction perovskite solar cells, a maximum power conversion efficiency of 17.12% was achieved. This work provides a deep understanding of the enhancement of the conductivity of PTAA by the BCF doping and LS treatment. In addition, a convenient and quick LS method was explored to improve the conductivity of the PTAA hole transport material. Our findings may help in improving the hole transport properties of other organic photoelectric materials and devices