title: Synthesis of tunable-band-gap "Open-Box" halide perovskites by use of anion exchange and internal dissolution procedures.
abstract: We demonstrate the synthesis of cuboid MAPbBr3 (MA=CH3NH3) microcrystals and subsequent conversion into open-box-like MAPb(Br(1-x)I(x))3 (0⩽x⩽1) microcrystals by anion exchange in MAI solution. During the substitution of Br(-) with I(-), the initial cuboid framework of MAPbBr3 crystals is retained. The preferential internal dissolution of MAPbBr3 due to the surface coverage and protection of MAPb(Br(1-x)I(x))3 induces voids inside the cuboid crystals, finally leading to open-box-like iodide-rich MAPb(Br(1-x)I(x))3. By controlling the degree of anion exchange, the intense light absorption of the product is able to be tuned in specific wavelengths throughout the visible range. This solution-phase anion exchange approach provides a synthetic strategy in designing sophisticated organolead halide perovskites structures as well as tuning the band gaps for further applications across a range of possible domains.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China; Anhui Key Laboratory of Molecule-Based Materials, The Key Laboratory of Functional Molecular Solids, Ministry of Education, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, PR China.
authors.forename: Zhengcui
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Baohua
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
authors.forename: Jian
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China. Electronic address: taochen@phy.cuhk.edu.hk.
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
keywords: Anion exchange; Kerkindall effect; Organolead halide perovskites; Tunable band gap