Lead‐Free Double Perovskite Cs₂AgBiBr₆: Fundamentals, Applications, and Perspectives

Abstract

Cs 2 AgBiBr 6 , as a benchmark lead-free double perovskite, has emerged as a promising alternative to lead-based perovskites because of its high stability, non-toxicity, exceptional optoelectronic properties, and multifunctionality. To encourage further research on Cs 2 AgBiBr 6 and its broad applications, in this review, its fundamental properties including the structure-property relation, synthesis, stability, origin of absorption and photoluminescence, electronphonon coupling, role of defects, charge carrier dynamics, and bandgap modulation are comprehensively emphasized. The recent progress on the wide applications including solar cells, light/X-ray detectors, and ferroelectric/magnetic devices are highlighted. Moreover, the challenges of Cs 2 Ag-BiBr 6 materials and related applications are discussed and perspectives are provided for guiding the future development of this research area.

Diverging Expressions of Anharmonicity in Halide Perovskites

“…The absence of local polar fluctuations may explain why Cs 2 AgBiBr 6 has more electronically active defects compared to the lead-based perovskites. [34,35,70]…”

“…It appears to have low mobility and deep-level defects compared to the lead-based perovskites. [32][33][34][35] Therefore, it is of interest to compare the structural dynamics of Cs 2 AgBiBr 6 to that of lead-based perovskites. This comparison will allow us to explore how anharmonic lattice dynamics are expressed in lead-free perovskite and investigate whether strong anharmonicity is related to the lead-based halide's excellent optoelectronic properties.…”

Air processed Cs2AgBiBr6 lead-free double perovskite high-mobility thin-film field-effect transistors

“…Hybrid organic–inorganic halide Perovskites like methylammonium lead iodide (CH 3 NH 3 PbI 3 ) have been the most dominant semiconducting channel materials used in the studies of Perovskite thin-film FETs 5 . All inorganic double perovskite material, Cs 2 AgBiBr 6 is considered to be one of the promising alternative non-toxic and highly stable materials in the family of perovskites exhibiting a long charge carrier lifetime, high charge carrier mobility in single crystals, and effective charge carrier masses comparable to those of lead-based organic–inorganic perovskite semiconductors 6 – 9 . Recent theoretical investigations suggest that the Cs 2 AgBiBr 6 material is a potential candidate for PV, photocatalytic and x-ray detector applications 10 – 12 .…”

Cs2AgBiBr6 Double Perovskites as Lead‐Free Alternatives for Perovskite Solar Cells?

“…We do not intend to provide a comprehensive review on the material, which can be found elsewhere. [17][18][19] Instead, we will sort the reported results and present a theoretical efficiency estimate based on measurement data without extrapolations to bandgaps. We will discuss major bottlenecks, also by comparing to leadhalide perovskites and report approaches to reduce them.…”