High Optical Gain in Stable MOF-Derived Composite Films Based on Perovskite Nanocrystals.

Metal halide perovskite nanocrystals hold great promise for low-cost optoelectronic and lasing applications, yet their integration into composite films is limited by poor stability under high excitation. We present a strategy to fabricate stable, ligand-free perovskite nanocrystal-based composites by combining lead-based metal-organic frameworks (MOFs) with methylammonium acetate ionic liquid. This single-step fabrication approach conducted in air yields compact, smooth (∼3 nm roughness), optically uniform composite films with a high perovskite incorporation level. These films exhibit broad spectral tunability over the 409-752 nm range, high photoluminescence quantum yields of up to 80%, and exceptional stability, maintaining > 80% emission intensity for over 190 h under elevated temperature and ultraviolet irradiation in air. Moreover, owing to efficient confinement and suppressed nonradiative losses, optimized composite films deliver a record modal gain of 1825 cm-1 at 350 µJ∙cm-2, which is among the highest values reported for perovskite nanocrystals. Our findings establish MOF-derived perovskite nanocrystal composites as a scalable platform for high-performance optoelectronics, paving the way toward practical perovskite-based lasers.