Prediction of the Role of Bismuth Dopants in Organic-Inorganic Lead Halide Perovskites on Photoelectric Properties and Photovoltaic Performance

Heterovalent Bi doping in lead halide perovskites has shown increased stability and high power conversion efficiency (PCE), yet the exact role it played remains poorly understood. Here, the comprehensive impact that Bi dopants can have on photoelectric and photovoltaic performances is predicted. Compared to pristine perovskites, the addition of a modest content (<0.4) of Bi can facilitate a decreased band gap with lower electron-hole pair creation energy, red-shifted optical absorption, enlarged Stokes shift, higher carrier mobility, and longer diffusion length. Moreover, the generation of charge carriers, intramolecular energy transfer, internal quantum efficiency, and transport performance will be tremendously improved, while the emission decay and recombination of band-edge carriers can be largely reduced, which leads to broadband photoluminescence quantum yields, higher short-circuit currents, and open-circuit voltages, thus improving the PCE. This work opens up new avenues for designing advanced functional perovskites with optimal Bi dopant content and superior photovoltaic performance.