Da Chen,Shiqiang Hao,Guojun Zhou,Chenkai Deng,Quanlin Liu,Shulan Ma,Christopher Wolverton,Jing Zhao,Zhiguo Xia
Low-dimensional organic–inorganic hybrid metal halides have emerged as broadband light emitters for phosphor-converted white light-emitting diodes (WLEDs). Herein, we report a new zero-dimensional (0-D) lead-free metal halide (PMA)3InBr6 [PMA+: (C6H5CH2NH3)+] that crystallizes in the monoclinic system with P21/c space group. The structure consists of slightly distorted [InBr6]3– octahedra surrounded by organic PMA+ cations. The direct band gap characteristic of (PMA)3InBr6 was demonstrated by density functional theory calculation, and its relatively wide band gap of 3.78 eV was experimentally determined. Upon 365 nm ultraviolet light excitation, (PMA)3InBr6 exhibited strong broadband orange luminescence with a full-width at half-maximum of ∼132 nm resulting from self-trapped exciton emission, and the photoluminescence quantum yield was determined to be ∼35%. A WLED fabricated by combining the orange-emitting (PMA)3InBr6, a green phosphor Ba2SiO4:Eu2+, and a blue phosphor BaMgAl10O17:Eu2+ exhibited a high color-rendering index of 87.0. Our findings indicate that the organic–inorganic hybrid (PMA)3InBr6 may have potential for luminescence-based applications.
Low-dimensional organic–inorganic metal halides have shown great application potential and new opportunities for use in solid-state lighting due to their excellent optical and electronic properties. However, the most studied hybrid compounds contain lead, which limits their application environments. The preparation of organic–inorganic metal halides with high luminous efficiency, long-term stability, and a lead-free composition for environmental protection has become an important goal for the design of materials. Here, novel Sb3+-doped indium-based metal halides, (CH3NH3)4InCl6·Cl, have been designed and synthesized via a simple mechanical ball milling method; in the lead-free zero-dimensional (0D) halide (CH3NH3)4InCl6·Cl, isolated [InCl6]3− octahedra are separated by methylamine cations. Under UV excitation, the bulk-phase powder exhibits broadband orange-yellow emission peaking at 607 nm with a full width at half-maximum of ∼160 nm upon incorporating Sb3+ into the (CH3NH3)4InCl6·Cl matrix. The photoluminescence quantum yield (PLQY) of Sb3+-doped (CH3NH3)4InCl6·Cl is as high as 67.72%. The effects of the Sb3+-doping concentration on the crystal structure and optical characteristic have been investigated. The indirect band gap characteristics of (CH3NH3)4InCl6·Cl were demonstrated via density functional theory (DFT) calculations, and the relatively wide band gaps of 3.83 eV and 2.99 eV of (CH3NH3)4InCl6·Cl and (CH3NH3)4ClInCl6:Sb3+ were experimentally determined. These experimental results suggest that the as-prepared Sb3+-doped (CH3NH3)4InCl6·Cl has potential applications in solid-state lighting devices.
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