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Dual‐Ion‐Diffusion Induced Degradation in Lead‐Free Cs 2 AgBiBr 6 Double Perovskite Solar Cells
Author(s) -
Ghasemi Mehri,
Zhang Lei,
Yun JungHo,
Hao Mengmeng,
He Dongxu,
Chen Peng,
Bai Yang,
Lin Tongen,
Xiao Mu,
Du Aijun,
Lyu Miaoqiang,
Wang Lianzhou
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202002342
Subject(s) - materials science , perovskite (structure) , halide , ion , diffusion , degradation (telecommunications) , vacancy defect , chemical physics , ionic bonding , photovoltaic system , optoelectronics , nanotechnology , chemical engineering , inorganic chemistry , crystallography , chemistry , thermodynamics , physics , ecology , telecommunications , computer science , organic chemistry , engineering , biology
Abstract Lead‐free double perovskite Cs 2 AgBiBr 6 has attracted increasing research interest in addressing the toxicity and stability challenges confronted by lead halide perovskites. While most of the studies on this Cs 2 AgBiBr 6 material have been focusing on photovoltaic performance and potential applications, its long‐term stability and degradation mechanism are well under‐explored. Herein, high‐quality Cs 2 AgBiBr 6 thin‐films are developed for lead‐free double perovskite solar cells with a decent efficiency of 1.91%. By exploring the ambient stability of these photovoltaic devices, it is found that the Cs 2 AgBiBr 6 exhibits a unique dual‐ion‐migration phenomenon, where Ag and Br ions gradually diffuse through the hole‐transporting layer in the long‐term operation. This phenomenon leads to the degradation of the Cs 2 AgBiBr 6 perovskite and subsequent device failure. Theoretical calculations indicate that low formation energies of the Ag and Br vacancies, and low diffusive energy barriers contribute to the dual‐ion‐migration effect. A possible mechanism involving a vacancy‐mediated ion‐migration is proposed to explain this phenomenon. These key findings are essential for halide double perovskites not only in providing a new knowledge base for further addressing the challenge of double perovskite stability, but also in extending their optoelectronic/electronic applications where mixed electronic, ionic and photonic properties may be desired.