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Controllable synthesis of CsxPbyBrz-based perovskites by a polar solvent-triggered transformation method and its application as an invisible security ink

Zhang, Wule, Wang, Zhenzhen, Lin, Pei, Wu, Di, Shi, Zhifeng, Chen, Xu, Xu, Tingting, Tian, Yongtao, Li, Xinjian
Journal of materials science 2020 v.55 no.16 pp. 6826-6833
methanol, solvents, toluene
Recently, all-inorganic CsPbX₃ (X = Cl, Br, I) perovskites have become one of the most promising candidates for photoelectronic and photovoltaic applications. Herein, we report the controllable synthesis of CsₓPbyBrz-based perovskites by a simple polar solvent-triggered (H₂O, CH₃OH) chemical transformation method. The phase of CsₓPbyBrz-based perovskites can be successfully converted from Cs₄PbBr₆ to CsPbBr₃ by using H₂O as a polar solvent and from CsPbBr₃ to CsPb₂Br₅ by using CH₃OH as a polar solvent, and this method can also be applied to synthesize Cs₄PbBr₆/CsPbBr₃ and CsPbBr₃/CsPb₂Br₅ composites by controlling parameters of transformation process. Moreover, a novel kind of encryption and decryption technology is developed based on the characteristics that the white Cs₄PbBr₆ reacts with H₂O to rapidly produce yellow CsPbBr₃, using the Cs₄PbBr₆ toluene solution as the invisible security ink and H₂O as the decryption key. Our results present a controllable route to realize transformation from Cs₄PbBr₆ to CsPbBr₃ and from CsPbBr₃ to CsPb₂Br₅.