Preparation and characterization of a layered perovskite-type organic–inorganic hybrid compound (C8NH6–CH2CH2NH3)2CuCl4

The organic–inorganic hybrid compound (C8NH6–CH2CH2NH3)2CuCl4 (AEI–CuCl4) was synthesized from ethanol solution containing copper chloride and 3-2-(aminoethyl) indole hydrochloride (AEI–HCl). High order diffraction peaks corresponding to (0 0 l; l = 2, 4, 6, …) observed in the X-ray diffraction profile of AEI–CuCl4 indicated the formation of hybrid crystal with layered perovskite structure. The organic–inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the AEI–CuCl4 perovskite and it showed characteristic absorptions of CuCl-based layered perovskite centered at 288 and 388 nm, as well as the photoluminescence peak at around 420 nm. The unaided-eye-detectable blue fluorescence emission comes from the cooperation of AEI–HCl and AEI–CuCl4 perovskite, in which protonized aminoethyl indole dominates the shape of the spectrum and the enhancement of emission intensity is due to the formation of the perovskite structure. The thermal analysis presented that the AEI–CuCl4 perovskite started to melt at 182 °C, together with the beginning of the decomposition of the hybrids. Compared with the organic–inorganic perovskite hybrids reported previously, the AEI–CuCl4 perovskite shows a novel stepwise decomposition behavior.