Circularly Polarized Luminescence from Zero‐Dimensional Hybrid Lead‐Tin Bromide with Near‐Unity Photoluminescence Quantum Yield

Abstract

Zero-dimensional (0D) hybrid metal halides with perfect host-guest structures are promising candidates to construct circularly polarized luminescence (CPL)-active materials. However, it still remains challenging to obtain 0D chiral metal halides with simultaneously strong CPL and high photoluminescence quantum yield. Here, a new enantiomeric pair of 0D hybrid lead-tin bromides, (RR/SS-C₆ N₂ H₁₆ )₂ Pb_0.968 Sn_0.032 Br₆ ⋅ 2H₂ O (R/S-PbSnBr ⋅ H₂ O), is reported. The R/S-PbSnBr ⋅ H₂ O compounds not only show intriguing self-trapped exciton emissions with near-unity quantum yield, but also present intense CPL with a dissymmetry factor g_lum of ±3.0×10^-3 . Such CPL activities originate from the asymmetric [SnBr₆ ]^4- luminophores in R/S-PbSnBr ⋅ H₂ O, due to the induced structural chirality by the organic ligands via N-H⋅⋅⋅Br hydrogen bonds. Furthermore, CPL emissions with tunable colors from R/S-PbSnBr ⋅ H₂ O and dehydrated compounds are reversibly observed, which extends their chiroptical applications.