Na–Cu-Codoped Halide Perovskite Nanocrystals Encapsulated in Pb(OH)I with Stable Red-Orange Emission: Implications for Optoelectronic Applications

The intrinsic structural lability and limited processability of inorganic halide perovskites heavily hamper their commercial applications. Herein, we develop a facile and scalable room-temperature (RT) water-based procedure for the synthesis of Na–Cu-codoped CsPbI x Br 3– x -embedded Pb(OH)I (denoted as the Na–Cu–CsPbI x Br 3– x @Pb(OH)I) composite to overcome the above-mentioned bottlenecks. Compared to Na doping, the codoping with Na and Cu leads to a slight shift of the photoluminescence (PL) peak position from ∼612 to 622 nm, increases the PL intensity by 32.5 times, and improves the PL quantum yield from 1% to 5%. Notably, the optimized Na–Cu–CsPbI x Br 3– x @Pb(OH)I composite displays outstanding stability under various harsh environments such as soaking in RT water or hot water (up to 90 °C) and annealing at high temperature, which indicates that Pb(OH)I can act as an effective water-blocking and protective encapsulation layer. It is more interesting that the photoluminescence (PL) intensity of Na–Cu–CsPbI x Br 3– x @Pb(OH)I can be significantly increased to 2.17 and 1.29 times after soaking the sample in RT water for 35 and 105 days, respectively, and 1.25 times even after immersing in hot water (90 °C) for 6 h, indicating an improved optical property. Meanwhile, the crystal structure and emission wavelength are maintained. The insight of this work is quite beneficial for designing highly stable inorganic perovskite-based nanomaterials for realization in light-emitting devices and other optoelectronic devices.