Synergistic Effect of Cation Composition Engineering of Hybrid Cs_1−xFA_xPbBr₃ Nanocrystals for Self‐Healing Electronics Application

Abstract Mixed‐cation hybrid perovskite nanocrystal (HPNC) with high crystallinity, color purity, and tunable optical bandgap offers a practical pathway toward next‐generation displays. Herein, a two‐step modified hot‐injection combined with cation compositional engineering and surface treatment to synthesize high‐purity cesium/formamidinium lead bromide HPNCs(Cs_1‐xFA_xPbBr₃) is presented. The optimized Cs_0.5FA_0.5PbBr₃ light‐emitting devices (LEDs) exhibit uniform luminescence of 3500 cd m⁻² and a prominent current efficiency of 21.5 cd A⁻¹. As a proof of concept, a self‐healing polymer (SHP) integrated with white LED backlight and laser prototypes exhibited 4 h autonomous self‐healing through the synergistic effect of weak reversible imine bonds and stronger H‐bonds. First, the SHP‐HPNCs‐initial and SHP‐HPNCs‐cut possess high long‐term stability and dramatically suppressed lead leakage as low as 0.6 ppm along with a low leakage rate of 1.11 × 10⁻⁵ cm² and 3.36 × 10⁻⁵ cm² even over 6 months in water. Second, the Cs_0.5FA_0.5PbBr₃ HPNCs and SHP‐induced shattered–repaired perovskite glass substrate show the lowest lasing threshold values of 1.24 and 8.58 µJ cm⁻², respectively. This work provides an integrative and in‐depth approach to exploiting SHP with intrinsic and entropic self‐healing capabilities combined with HPNCs to develop robust and reliable soft‐electronic backlight and laser applications.