Stable, High‐Sensitivity and Fast‐Response Photodetectors Based on Lead‐Free Cs₂AgBiBr₆ Double Perovskite Films

Abstract Solution‐processed metal halide perovskites (MHPs) have demonstrated great advances on achieving high‐performance photodetectors. However, the intrinsic material instability and the toxicity of lead still hinder the practical applications of MHPs‐based photodetectors. In this work, the first highly sensitive and fast‐response lead‐free perovskite photodetectors based on Cs₂AgBiBr₆ double perovskite films are demonstrated. A convenient solution method is developed to deposit high‐quality Cs₂AgBiBr₆ film with large grain sizes, low trap densities, and long charge carrier lifetimes. Incorporated within a photodiode device architecture comprised of optimized hole‐ and electron‐transporting layers, lead‐free perovskite photodetectors are achieved exhibiting a high detectivity of 3.29 × 10¹² Jones, a large linear dynamic range of 193 dB, and a fast response time of ≈17 ns. All the key figures of merit of the devices are comparable with the reported best‐performing photodetectors based on lead halide perovskites. In addition, the resulting devices exhibit excellent thermal and environmental stability. The nonencapsulated devices show negligible degradation after thermal stressing at 150 °C and less than 5% degradation in the photoresponsivity after storage in ambient air for ≈2300 h. The results demonstrate the great potential of the lead‐free Cs₂AgBiBr₆ double perovskite in applications for environmentally friendly and high‐performance photodetectors.