In Situ Embedding Synthesis of Highly Stable CsPbBr<sub>3</sub>/CsPb<sub>2</sub>Br<sub>5</sub>@PbBr(OH) Nano/Microspheres through Water Assisted Strategy
Kaimin Du, Lingjun He, Shuyan Song, Jing Feng, Li Yao, Manli Zhang, Huwei Li, Chengyu Li, Hongjie Zhang
Abstract
Abstract The disappointing stability of perovskites, especially in water, remains a key issue hindering their further commercialization. Here, CsPbBr 3 /CsPb 2 Br 5 @PbBr(OH) (PQDs@PbBr(OH)) nano/microspheres with superior stability and outstanding photoluminescence quantum yield (PLQY, ≈98%) are fabricated through a water‐assisted process. The nano/microspheres can maintain excellent photoluminescence (PL) intensity and high PLQY (≈90%) when immersed in water for more than 18 months. By changing the water content in the reaction mixture, the phase, particle size, and PL peaks of the nano/microspheres will change. Compared with CsPbBr 3 /Cs 4 PbBr 6 nanocrystals synthesized without water, PQDs@PbBr(OH) nano/microspheres exhibit better thermal stability, photostability, and superior stability in water. Based on the first‐principles calculations, the enhanced stability results from PbBr(OH) with high decomposition enthalpy in water, which can effectively prevent water from contacting PQDs embedded in it. Moreover, white light‐emitting diodes are fabricated by mixing green‐emitting PQDs@PbBr(OH) powder and K 2 SiF 6 :Mn 4+ (KSF) red phosphor on a 460 nm blue chip and the device shows a high luminous efficacy of 101.27 lm W −1 at 10 mA. This work not only provides a reliable method for the facile preparation of ultrastable perovskites, but also has great potentials for future practical applications.