Kinetically Controlled Growth of Cu ²⁺ -Doped CsPbI ₃ Nanoplates for Defect Regulation and Enhanced Stability

All-inorganic lead halide perovskites (CsPbX 3 ) have attracted extensive attention due to their outstanding optoelectronic properties; however, their practical applications are severely limited by structural instability and defect-induced nonradiative recombination. Herein, we report a kinetically controllable hot-injection strategy to synthesize Cu 2+ -doped CsPbI 3 nanoplates (NPLs). By precisely regulating the injection timing and amount of hydroiodic acid, a critical balance nucleation and growth is established, enabling the formation of uniform NPLs. Structural analysis confirms successful incorporation of Cu 2+ into the CsPbI 3 lattice without phase transition, accompanied by slight lattice contraction. Importantly, Cu 2+ doping does not significantly change the bandgap but effectively reduces defect density, as evidenced by decreased Urbach energy and prolonged carrier lifetime. As a result, the photoluminescence quantum yield is maximized at an optimal doping level of 10%, reflecting effective defect suppression. Time-resolved photoluminescence further reveals suppressed nonradiative recombination and improved carrier dynamics. Moreover, the doped NPLs exhibit significantly enhanced stability, retaining ∼82% of their initial PL intensity after 20 days, compared to ∼8% for pristine samples. Overall, this work provides an effective strategy for simultaneously improving the luminescence performance and environmental stability of perovskite nanomaterials through defect engineering.