Ultrastable Photodetectors Based on Blue CsPbBr₃ Perovskite Nanoplatelets via a Surface Engineering Strategy

Recently, photodetectors based on perovskite nanoplatelets (NPLs) have attracted considerable attention in the visible spectral region owing to their large absorption cross-section, high exciton binding energy, excellent charge transfer properties, and appropriate flexibility. However, their stability and performance are still challenging for perovskite NPL photodetectors. Here, a surface engineering strategy to enhance the optical stability of blue-light CsPbBr₃ NPLs by acetylenedicarboxylic acid (ATDA) treatment has been developed. ATDA has strong binding capacity and a short chain length, which can effectively passivate defects and significantly improve the photoluminescence quantum efficiency, stability, and carrier mobility of NPLs. As a result, ATDA-treated CsPbBr₃ NPLs exhibit improved optical properties in both solutions and films. The NPL solution maintains high PL performance even after being heated at 80 °C for 2 h, and the NPL film remains nondegradable after 4 h of exposure to ultraviolet irradiation. Especially, photodetectors based on the treated CsPbBr₃ NPL films demonstrate exceptional performance, especially when the detectivity approaches up to 9.36 × 10¹² Jones, which can be comparable to the best CsPbBr₃ NPL photodetectors ever reported. More importantly, the assembled devices demonstrated high stability (stored in an air environment for more than 30 days), significantly exceeding that of untreated NPLs.