Ligand-mediated secondary growth of CsPbBr3 nanocrystals under ambient atmosphere for stable and efficient photodetectors

Summary Ligand engineering is a vital strategy for enhancing the optoelectronic performance and stability of all-inorganic metal halide perovskite nanocrystals (NCs). In this study, we demonstrate CsPbBr₃ NCs with tunable sizes (18.8–34.7 nm) via ligand-mediated secondary growth via a two-step ligand-washing (2W) procedure. This approach significantly boosts the photoluminescence quantum yield (PLQY) from 21.46% to 38.95% in thin-films and 90.77% in solution. The entire synthesis was conducted via a hot-injection method under ambient air. The resulting 2W-processed thin films exhibit exceptional robustness, retaining nearly 65% of their initial PLQY after thermal annealing at 120°C and over 98% after continuous UV irradiation. Furthermore, photodetectors fabricated with 2W-CsPbBr₃ achieved a high low-light responsivity of 2.79 AW⁻¹—a 4-fold improvement over untreated devices—and a stable detectivity of 1.8 × 10⁹ Jones due to minimized surface defects. This work provides a simple and effective pathway for developing high-performance, stable perovskite-based optoelectronics in ambient environments.