Liquid nitrogen quenching boosts emission and stability of Cs3Cu2I5 perovskite nanocrystals toward multifunctional optoelectronic applications

Lead-free Cs 3 Cu 2 I 5 perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications owing to their non-toxicity and intrinsic blue emission. However, their practical application is hindered by defect-dominated low photoluminescence quantum yield (PLQY) and poor environmental stability. Herein, we propose an ultrafast liquid‑nitrogen (LN) quenching strategy integrated with one‑pot synthesis, which delivers an ultra‑high cooling rate of 35 K/s faster than conventional ice‑water (IW) cooling (1 K/s). This abrupt thermal termination effectively suppresses Ostwald ripening, ion migration and surface ligand detachment, thereby promoting uniform size distribution, inducing lattice contraction and reducing the non-radiative defects. The obtained Cs 3 Cu 2 I 5 NCs exhibit a remarkable PLQY up to 85% and exceptional stability, maintaining beyond 80% of initial PL intensity after ambient storage for 35 days, aqueous exposure for 36 h and continuous UV irradiation for 48 h. Moreover, the LN-quenched NCs were successfully integrated into X-ray scintillator film achieving a spatial resolution of 10 lp/mm, and their colloidal ink enabled stimulus-responsive information encryption and fluorescence anti-counterfeiting patterns, attributed to enhanced self-trapped exciton (STE) emission and robust structural integrity. This work establishes ultrafast LN quenching as a universal and feasible strategy for fabricating highly luminescent and stable perovskite NCs, paving the way for multifunctional optoelectronic applications.