Black phosphorus doped Poly(triarylamine) as hole transport layer for highly efficient perovskite solar cells

Charge transport layer plays a critical role in high-performance perovskite solar cells (PSCs). Herein, few-layered 2D black phosphorus (BP) nanosheet doped poly(triarylamine) (PTAA) is employed as hole transport layer for PSCs. The BP:PTAA significantly improves charge extraction at perovskite/BP:PTAA interface together with the smaller energy barrier, the increased conductivity of the PTAA film, and the formation of the high-quality perovskite film with enlarged crystal gain size, which suppress the interfacial charge recombination and trap-assisted recombination. As a result, the champion device using BP:PTAA produces the higher power conversion efficiency of 20.49% than the control device of 18.26%. Moreover, the remarkable improvement in device stability has been demonstrated attributed to the more hydrophobicity of BP:PTAA and the perovskite layer with less defect states. This work provides an effective hole transport layer for PSCs, which is comparable with the commonly used 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ):PTAA.