Coupling Intracompound Charge Transfer and Cluster-Centered Excited States in Cu(Ⅰ) Halide Hybrids for Efficient White Light Emission

摘要

0D hybrid organic–inorganic metal halides have attracted significant interest due to their unique optoelectronic properties, but attainment of efficient and stable white light emission (WLE) in such compounds remains a challenge. Here, efficient WLE via a molecular design that couples intracompound charge transfer and cluster-centered excited states in 0D halide hybrids is demonstrated. Two Cu(Ⅰ) halide hybrids, K(18-crown-6)Cu_2Br_3 and Na_4(18-crown-6)_5In_2Cu_4Br_(14)·8H_2O, are synthesized wherein luminescent Cu_4Br_6~(2?) clusters are isolated from each other and surrounded by 18-crown-6 coordinated alkali metal cations. In the case of K(18-crown-6) Cu_2Br_3, Cu_4Br_6~(2?) clusters are only partially isolated, leading to strong orange emission with a photoluminescence quantum yield (PLQY) of 53 under UV excitation. Strikingly, to a larger extent of isolation as that, in Na_4(18-crown- 6)_5In_2Cu_4Br_(14)·8H_2O as a result of the incorporation of nonemissive InBr_4? clusters, intense white light emission with a PLQY of 97 is achieved. The dual cluster-centered states, coupled with a mixed metal-to-ligand and halideto- ligand charge transfer state, are responsible for this bright white luminescence. This work provides new design principles for expanding the materials library for single-component, solid-state WLE.