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

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 Pb0.968 Sn0.032 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 glum 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.