Low-dimensional lead halide perovskite materials recently have drawn much attention owing to the intriguing broadband emissions; however, the toxicity of lead will hinder their future development. Now, a lead-free (C4 H14 N2 )2 In2 Br10 single crystal with a unique zero-dimensional (0D) structure constituted by [InBr6 ]3- octahedral and [InBr4 ]- tetrahedral units is described. The single crystal exhibits broadband photoluminescence (PL) that spans almost the whole visible spectrum with a lifetime of 3.2 μs. Computational and experimental studies unveil that an excited-state structural distortion in [InBr6 ]3- octahedral units enables the formation of intrinsic self-trapped excitons (STEs) and thus contributing the broad emission. Furthermore, femtosecond transient absorption (fs-TA) measurement reveals that the ultrafast STEs formation together with an efficient intersystem crossing has made a significant contribution to the long-lived and broad STE-based emission behavior.
Keywords: indium; lead-free materials; low-dimensional materials; photoluminescence; self-trapped excitons.
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