High Performance of Cs₂AgBiBr₆ Perovskite‐based Photodetectors by Adding DEAC

Perovskite-based photodetectors (PDs) are broadly utilized in optical communication, non-destructive testing, and smart wearable devices due to their ability to convert light into electrical signals. However, toxicity and instability hold back their mass production and commercialization. The lead-free Cs₂AgBiBr₆ double perovskite film, promised to be an alternative, is fabricated by electrophoretic deposition (EPD), which compromises film quality. Herein, we improved the quality of the Cs₂AgBiBr₆ films and the performance of PDs by adding N-acetylethylenediamine (DEAC) to Cs₂AgBiBr₆ perovskite precursor for EPD, in which the ligand DEAC provides a pair of lone electrons to Bi³⁺, forming coordinate covalent bonds. The optimized PDs have high detectivity, up to 4.4×10¹² Jones, and high stability in the air. The high-performance, flexible Cs₂AgBiBr₆ perovskite PDs were fabricated on this basis, it also achieved the detectivity up to 3.2×10¹² Jones with excellent bending cycle stability. These results propose a feasible approach to improving the crystallization of double perovskite thin films by introducing ligands during the EPD process. Furthermore, they demonstrate enhanced optoelectronic performance, indicating that this method is also applicable to halide perovskites, offering an effective strategy to improve their film quality.