Lead‐Free All‐Inorganic Cesium Bismuth Iodide‐Based Perovskite Solar Cells: Recent Advances, Current Limitations, and Future Prospects

Abstract

Remarkable achievements have been made in the development of perovskite solar cells (PSCs) with a rapidly boosting rate of power conversion efficiencies (PCEs) from 3.8% to 26.1%. Nevertheless, the toxicity of lead (Pb) elements and the hygroscopicity of organic cations in high‐efficiency PSCs severely hamper the commercialization of this technology. Consequently, Pb‐free all‐inorganic PSCs have received increasing attention recently to resolve the above‐mentioned toxicity and instability problems. Among various Pb‐free all‐inorganic halide perovskites, caesium bismuth iodide (CBI)‐based perovskites have gained particular attention as light absorbers in PSCs due to the tunable/small band gaps, long carrier diffusion length/lifetime and superb sunlight absorption coefficients. Nevertheless, the PCEs of CBI‐based PSCs are still far away from Pb‐based organic‐inorganic counterparts because of the low structural dimensions and inferior perovskite film quality. Herein, the recent advances of CBI‐based perovskites as light‐absorbing materials in Pb‐free all‐inorganic PSCs are reviewed by emphasizing the distinct structural/optical/electronic properties and currently existing limitations. Additionally, several distinct strategies to boost the PCEs and robusticity of CBI‐based PSCs are presented. Finally, the unsolved key problems and future directions of CBI‐based PSCs are proposed, aiming to provide important insights for the further development of CBI‐based PSCs to realize sustainable, non‐toxic, high‐performance perovskite photovoltaics.This article is protected by copyright. All rights reserved.

Fabrication and Characterization of a Lead-Free Cesium Bismuth Iodide Perovskite through Antisolvent-Assisted Crystallization

“…Moreover, perovskites made with all-inorganic lead-free absorbers have demonstrated superior stability in the face of humidity, light, and heat [13,[17][18][19]. Allinorganic lead-free perovskites solar cells created by chemically combining Cs, Bi, and halide elements are among the lead-free compounds under investigation [20][21][22][23]. When compared to tin-based perovskites which offer the highest efficiency among lead-free substitutes, cesium bismuth iodide provides superior stability under ambient conditions.…”

“…The surface deteriorates, leaving numerous voids and pinholes, as well as having poor reproducibility. Moreover, low dimensionality causes the materials to have a large bandgap, increased exciton energy, low charge carrier mobility, and modest absorption intensity [20,32]. Nevertheless, uniform surface morphology and good surface coverage are important film formation parameters for the production of perovskite cells with good optoelectronic properties and high reproducibility [6].…”