Core-shell CsPbBr3@Cs4PbBr6 nanocrystals dispersed in thermoplastic polyurethane as writeable heat-resistant fluorescent inks

Abstract The cesium lead halide perovskites CsPbX3 (X = Cl, Br, I) have received extensive attention in the solar cell and light-emitting devices owing to their excellent optical and electronic properties. However, in practical applications, CsPbX3 often suffers from many disturbances caused by changes in the external environment, which will weaken its performance. In order to better solve this issue, a series of encapsulation strategies have been proposed to protect the stability of CsPbX3. In particular, the derivative Cs4PbX6 of CsPbX3 was well received as a shell protective material because it does not introduce new elements. Here, we prepared large-yield stable CsPbBr3@Cs4PbBr6 core-shell nanocrystals (NCs) by adjusting the initial ratio of Cs/Pb using one-pot route. At the same time, the growth process of CsPbBr3@Cs4PbBr6 NCs were analyzed, and their stability was evaluated under atmospheric conditions. The results show that CsPbBr3@Cs4PbBr6 NCs exhibit excellent stability compared to the pure phase CsPbBr3 NCs, and thus the passivation of Cs4PbBr6 to CsPbBr3 was obtained. Subsequently, a writable fluorescent ink by mixing CsPbBr3@Cs4PbBr6 NCs and thermoplastic polyurethane (TPU) was developed, which held excellent heat-resistance stability under multiple heating-cooling cycles. Our research will greatly simplify the preparation process of stabilized CsPbBr3@Cs4PbBr6 core-shell NCs and provide alternative options for the commercial development of perovskite materials.