The dual band and white-light emission from piperazine halide perovskites

Abstract

We presented dual band and white-emission materials with the combination of (C₆H₁₂N₂H₂)₄Pb₅Br₁₈ ((C₆H₁₂N₂H₂)₄⁺ = DABCO) and metal halides, corner-sharing [PbBr₆]⁴⁻ and edge-sharing [SnCl₆]⁴⁻ inorganic frameworks, respectively. The (DABCO)₄Pb₅Br₁₈ perovskite crystallizes in the tetragonal space group I4/mcm, which consists of corner-sharing double chains and corner-sharing threads, and the DABCO cations are positioned in the space of the open 3D inorganic framework that connect to the adjacent bromine atoms via hydrogen bonding, which is N–H⋯Br (2.70–3.12 Å). Also, they are present in symmetrical positions with respect to each other. This shows the dual band photoluminescence emission that results from the combination of the 2D and the 3D perovskite band-edge absorption. The (DABCO)Sn₂Cl₆ compound has one dimensional (1D) zigzag edge-sharing octahedral [SnCl₆]⁴⁻ moieties in which each octahedral [SnCl₆]⁴⁻ framework is connected to square pyramidal [SnCl₅]³⁻ by edge sharing. It exhibits broadband white-light emission. From time-resolved photoluminescence, the (DABCO)₄Pb₅Br₁₈ perovskite exhibits a faster emission decay lifetime due to the radiative recombination process. However, the (DABCO)Sn₂Cl₆ perovskite shows a long emission lifetime due to the self-trapped exciton process that originated from the distorted 1D structure. We expect that these results will provide a strategy to design new stable perovskite materials with enhanced performance for perovskite light-emitting-diodes for commercial applications in displays and solid-state lighting.