Highly‐Sensitive, Stable, and Fast‐Response Lead‐Free Cs2AgBiBr6 Double Perovskite Photodetectors Enabled by Synergistic Engineering of Doping Na+/Ce3+ and Integrating Ag Nanoparticles Film

Abstract Lead‐free double halide perovskites stand out as a promising material for constructing stable and environmental‐friendly photodetectors (PDs) because of the excellent stability and nontoxicity. However, the performance (e.g., detectivity and response speed) of lead‐free double halide perovskites based PDs is still low. Herein, highly sensitive, stable, and fast‐response Cs 2 AgBiBr 6 perovskite PDs are presented by synergistic engineering of doping optimization of Na + /Ce 3+ and integrating with Ag nanoparticles (NPs). Compared to pristine Cs 2 AgBiBr 6 , Cs 2 AgBiBr 6 :Na + ,Ce 3+ film is endowed with higher crystallization quality and better stability after Na + ,Ce 3+ codoping, toward the reduced defect density, the improved charge mobility. Meanwhile, a significantly enhanced charge extraction and transport in Cs 2 AgBiBr 6 :Na + ,Ce 3+ /Ag NPs hybrid film is achieved by further integrating with Ag NPs. Finally, Cs 2 AgBiBr 6 :Na + ,Ce 3+ /Ag NPs hybrid film‐based PDs are developed, delivering high detectivity of 1.34 × 10 12 Jones@460 nm and 1.18 × 10 12 Jones@370 nm, which is the relatively high in lead‐free double halide perovskites PDs and exceeds the most results of the previous reports in the ultraviolet and visible range. The devices also show outstanding stability and fast‐response time (395 ns). This work opens up a novel frontier for developing lead‐free perovskite PDs.