Photophysics in Cs 3 Cu 2 X 5 (X = Cl, Br, or I): Highly Luminescent Self-Trapped Excitons from Local Structure Symmetrization
2020; American Chemical Society; Volume: 32; Issue: 8 Linguagem: Inglês
10.1021/acs.chemmater.9b05321
ISSN1520-5002
AutoresLinyuan Lian, Moyan Zheng, Peng Zhang, Zhi Zheng, Kang Du, Wen Lei, Jianbo Gao, Guangda Niu, Daoli Zhang, Tianyou Zhai, Shengye Jin, Jiang Tang, Xiuwen Zhang, Jianbing Zhang,
Tópico(s)Inorganic Chemistry and Materials
ResumoSelf-trapped excitons (STEs) in metal halide materials are attracting an increasing level of interest due to their unique light emission properties. Light emission from STEs in metal halides is usually associated with excited-state structural deformation, which lowers the symmetry of local structures, as seen for the STEs in a wide range of materials systems. Here, we reveal a prototypic STE-associated structural "distortion" that, however, enhances the symmetry of local structures, in a series of all-inorganic copper(I)-based halides Cs3Cu2X5 (X = Cl, Br, or I). We further find that the emission peaks of Cs3Cu2X5 blue-shift when the halogen changes from Cl to Br to I, which is the opposite of the trends found in traditional halide perovskites. This phenomenon is attributed to a synergetic combination of the significant change in band gap associated with structural deformation and a strong excitonic effect. Due to the highly localized electron and hole upon photoexcitation, Cs3Cu2Cl5 shows an extremely long and temperature-sensitive photoluminescence (PL) lifetime among metal halide materials with STEs. Remarkably, strong green emission with a PL quantum yield exceeding 90% is found in Cs3Cu2Cl5, opening the way to designing light emission compounds based on local symmetry-enhancing STE mechanisms.
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