Black phosphorus quantum dots as dual-functional electron-selective materials for efficient plastic perovskite solar cells

Abstract

Organic–inorganic hybrid metal halide perovskite solar cells (PSCs) have attracted tremendous research interest due to their high power conversion efficiency and simple fabrication. However, the exploitation of new electron-selective materials which can simultaneously tailor the quality of metal halide perovskite film for low-temperature-produced plastic organic–inorganic halide perovskite solar cells (PSCs) is of key importance but remains a great challenge. Herein, facile solution-processed black phosphorus quantum dots (BPQDs) with ambipolar conductivity are developed as dual-functional electron-selective layer (ESL) in plastic PSCs. The BPQD ESL plays crucial roles in both forming a cascade energy level for fast electron extraction and guiding the crystallization behavior of the perovskite to yield compact perovskite films with less traps, good crystallization and ordered orientation. The perovskite films deposited on the BPQD ESL exhibit excellent optoelectronic properties, and the resulting plastic planar perovskite solar cells possess a reasonably high efficiency of 11.26%. The 3.15-fold enhancement in efficiency arises from both the efficient electron extraction and suppressed radiative and trap-assisted non-radiative recombination compared with the devices built on the bare ITO surface without an ESL. This work paves a promising way for developing novel electron-selective non-oxide materials for highly efficient solar cells.