Excitation‐Selective and Double‐Emissive Lead‐Free Binary Hybrid Metal Halides for White Light‐Emitting Diode and X‐Ray Scintillation

Abstract Zero‐dimensional (0D) organic metal halides comprising heterogeneous metal cations in single phase can achieve multiple luminous emissions enabling them toward multifunctional light‐emitting applications. Herein, A novel single crystal of (C 8 H 20 N) 4 SbMnCl 9 containing two luminescent centers of [SbCl 5 ] 2− pentahedrons and [MnCl 4 ] 2− tetrahedrons is reported. The large distance between Sb–Sb, Mn–Mn, and Sb–Mn as well as theory calculation indicate negligible interaction between individual centers, thus endowing (C 8 H 20 N) 4 SbMnCl 9 with excitation‐dependable and efficient luminescence. Under near‐UV excitation, only orange emission originates from self‐trapped excitons recombination in [SbCl 5 ] 2− pentahedron occurs with photoluminescence quantum yield (PLQY) of 91.5%. Under blue‐light excitation, only green emission originating from 4 T 1 ‐ 6 A 1 transition of Mn 2+ in [MnCl 4 ] 2− tetrahedrons occurs with PLQY of 66.8%. Interestingly, upon X‐ray illumination, both emissions can be fully achieved due to the high‐energy photon absorption. Consequently, (C 8 H 20 N) 4 SbMnCl 9 is employed as phosphors to fabricate white light‐emitting diodes optically pumped by n ‐UV chip and blue‐chip thanks to its excitation‐dependable property. Moreover, it also shows promising performance as X‐ray scintillator with low detection limit of 60.79 nGy air S −1 , steady‐state light yield ≈54% of commerical scintillaotr LuAG:Ce, high resolution of 13.5 lp mm −1 for X‐ray imaging. This work presents a new structural design to fabricate 0D hybrids with multicolor emissions.