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

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.