We prepare a series of two-dimensional (2D) tin-based perovskite (RNH2)2SnBr4 with different carbon chains. All of them have extra-large Stokes shifts, broad emission, and ultralong PL lifetimes. The PLQYs of (C8H17NH2)2SnBr4 and (OAm)2SnBr4 powders reach up to 54 and 60%, respectively. Density functional theory calculations and experimental results reveal that the properties of 2D Sn-based perovskites may originate from self-trapped excitons, which result from excited-state structural deformation. The results show that the [SnBr6]4– octahedron distorted by the carbon chain with arrangement distortion changes the photophysical properties of 2D tin-based perovskite. Furthermore, (OAm)2SnBr4 powders are used to engineer UV pumped light-emitting diodes. This work provides new strategies for the preparation of environmentally friendly perovskite materials.
Jingkun Xu,Shiming Guo,Junfeng Qu,Shuhong Xu,Chunlei Wang,Dayan Ban,Yiping Cui
All-inorganic cesium lead halide perovskite nanocrystals (NCs) are quite promising materials for emission-based applications. However, the intrinsic toxicity of lead, as well as the weak stability, remains to be resolved. Exploring more and more types of lead-free NCs with high photoluminescence quantum yields (PLQYs) and high stability is a fundamental task. This work gave the first example of copper doped cesium halide (Cu:CsX, X = Br, Cl/Br, Br/I) NCs with good stability and high PLQYs (∼31.2%), which could act as a new member of the lead-free NC family. A simple single-step ultrasonic method was applied for the synthesis of environmentally friendly Cu:CsX NCs. By varying the halide composition, the emission wavelength of Cu:CsX can be shifted within 450–505 nm. The as-prepared NCs show highly uniform size and excellent stability. Finally, UV pumped light-emitting diodes are demonstrated by using Cu:CsX NCs as a color conversion layer.
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