Branched Alkyl Chains Tunable Organic-Inorganic Hybrid Manganese Halides for Anti-counterfeiting, White Light-emitting Diode and X-ray Imaging Applications

Manganese-based organic–inorganic metal halides (Mn-based OIMHs) scintillators have aroused a research upsurge due to their outstanding photoluminescence performance, low toxicity, and tunable structures. Herein, we demonstrate a molecular engineering strategy that synergistically enhances luminescence efficiency and radiation sensitivity by systematic elongation of branched alkyl chains in phosphonium-based cations. The (4-DEATBP)MnBr₄ (4-DEATBP = (4-(diethylamino)butyl)triphenylphosphonium) crystal exhibits remarkable thermochromic luminescence properties and anti-thermal quenching effect, highlighting the application potential in high-temperature anti-counterfeiting and information encryption. Through effective chain elongation, the (4-DBATBP)MnBr₄ (4-DBATBP = (4-(dibutylamino)butyl)triphenylphosphonium) single crystal achieves an impressive photoluminescence quantum yield (PLQY) of 100% and exhibits superior performance under X-ray irradiation, with a high light yield of 67953 photons MeV⁻¹ and a low limit of detection (LOD) of 10.45 nGy s⁻¹. Additionally, the glassy (4-DBATBP)MnBr₄ demonstrates an impressive spatial resolution of 25 lp mm⁻¹. (4-DBATBP)MnBr₄ shows great application potential in the fields of white light-emitting diode (WLED) and express security check due to its outstanding luminescence performance. This work not only offers two kinds of new Mn-based OIMH materials but also authenticates the role of extending the branched alkyl chain for improving the photoluminescence performance.