[S(CH ₃ ) ₃ ] ₂ (MnBr ₄ ): A Mn‐Based Hybrid Bromide With High Photoluminescence Quantum Yield and Stable X‐Ray Detection Performance

ABSTRACT Organic‐inorganic hybrid metal halides have emerged as highly promising X‐ray scintillating materials due to their diverse structures and tunable luminescence properties. In this study, we report a manganese‐based zero‐dimensional hybrid halide, [S(CH 3 ) 3 ] 2 (MnBr 4 ), exhibiting excellent photoluminescence and stable X‐ray detection performance. The synthesized [S(CH 3 ) 3 ] 2 (MnBr 4 ) crystals exhibit intense green emission under ultraviolet light excitation. Photoluminescence measurements show that the emission center is located at 520 nm and the photoluminescence quantum yield is as high as 95.3%. The green emission should be attributed to the 4 T 1 6 A 1 electronic transition associated with the MnBr 4 2− tetrahedra. The temperature‐induced blue shift and broadening of the emission peak are attributed to the competition between lattice thermal expansion and electron‐phonon coupling, as revealed by temperature‐dependent photoluminescence studies within the framework of radiative transition mechanisms. Moreover, [S(CH 3 ) 3 ] 2 (MnBr 4 ) displays stable X‐ray detection performance, maintaining a stable radioluminescence intensity of 99.27% during prolonged (>2000 s) X‐ray irradiation cycles. These results demonstrate the promising applications of [S(CH 3 ) 3 ] 2 (MnBr 4 ) as a luminescent material and X‐ray detector material, and also highlight the potential of hybrid halides containing sulfur‐based organic cations.