Luminescent hybrid halides with various centering metal cations (Zn, Cd and Pb) and diverse structures

Organic-inorganic hybrid metal halides have been extensively studied because of their great potential in optoelectronics. Herein, we report three hybrid metal halides (Bmpip)₂ZnBr₄, (Bmpip)₂CdBr₄, and (Bmpip)₈Pb₁₁Br₃₀ (where Bmpip⁺ is 1-butyl-1-methyl-piperidinium, C₁₀H₂₂N⁺). (Bmpip)₂ZnBr₄ and (Bmpip)₂CdBr₄ crystallize in the P2₁/c space group with zero-dimensional crystal structures with [MBr₄]^2- (M = Zn, Cd) tetrahedra isolated by Bmpip⁺. (Bmpip)₈Pb₁₁Br₃₀ crystallizes in the triclinic space group P1̄ with one-dimensional corrugated chains constructed from face-sharing [PbBr₆]^4- octahedra. All of the compounds exhibit excellent ambient and thermal stability. Under UV excitation, all three compounds exhibit very broad emissions. Temperature-dependent photoluminescence measurements indicate that the broad emissions of (Bmpip)₂ZnBr₄ and (Bmpip)₂CdBr₄ can be attributed to both the organic cations and self-trapped excitons (STEs) and that the emission of (Bmpip)₈Pb₁₁Br₃₀ is assigned to STEs. Density functional theory calculations reveal that the three compounds adopt a direct band gap. This work enriches our understanding of the structure types of hybrid metal halides while revealing their diverse emission mechanisms.