School of Materials Science and Engineering Zhengzhou University Zhengzhou the People's Republic of China
Manying Liu
Key Laboratory of Micro‐Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, College of Chemical and Materials Engineering Xuchang University Xuchang the People's Republic of China
Yange Zhang
Key Laboratory of Micro‐Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, College of Chemical and Materials Engineering Xuchang University Xuchang the People's Republic of China
Dandan Zhao
Key Laboratory of Micro‐Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, College of Chemical and Materials Engineering Xuchang University Xuchang the People's Republic of China
Yan Lei
Key Laboratory of Micro‐Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, College of Chemical and Materials Engineering Xuchang University Xuchang the People's Republic of China
Chaoliang Zhao
Key Laboratory of Micro‐Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, College of Chemical and Materials Engineering Xuchang University Xuchang the People's Republic of China
Peng Zhang
School of Materials Science and Engineering Zhengzhou University Zhengzhou the People's Republic of China
Erjun Zhou
College of Biological and Chemical Engineering Jiaxing University Jiaxing the People's Republic of China
Zhi Zheng
School of Materials Science and Engineering Zhengzhou University Zhengzhou the People's Republic of China
Abstract Considering sustainable development factors such as element abundance, cost, environmental friendliness, and stability, the research and development of novel inorganic non‐lead perovskites are very significant. Copper‐silver‐bismuth iodide (CABI) is a promising solar cell material with halide perovskite genes, possessing eco‐friendly, element‐rich, and cost‐effective characteristics. The fabrication of high‐quality CABI films with tailored compositions still poses a substantial hurdle. We developed a CuAgBi2I8 material that effectively reduced the bandgap to 1.69 eV by optimizing Bi distribution to create an environment conducive to in‐situ redox reactions of Bi with I2, Cu, and Ag via vapor‐phase synthesis. This strategy proved highly effective in synthesizing high‐quality CuAgBi2I8 compound, accompanied by significant improvements in film quality, including enhanced crystallinity, minimized defects, and reduced non‐radiative recombination. The crystal structure of CuAgBi2I8 and mechanisms of elemental reactions and diffusion are discussed. Devices featuring the structure FTO/c‐TiO2/m‐TiO2/CuAgBi2I8/CuI/Spiro‐OMeTAD/carbon achieved a champion efficiency of 3.21%, the highest for CABI solar cells. This work provides a novel idea and approach to governing the gas–solid element diffusion and reaction for high‐quality CABI and related halide perovskite films.
