Triexciton induced RGB emission of organic-inorganic zirconium halide perovskites

Abstract Materials with two or more excitons that emit different fluorescence under different excitation sources have great potential in optical applications, but luminous materials with three-exciton emission characteristics have been largely undeveloped. Here, we report a novel zero-dimensional (0D) organic-inorganic hybrid ((C2H5)4N)2ZrCl6 perovskite with multiple exciton emission properties. The zirconium-based perovskite exhibits a red emission around 620 nm, a green emission at 527 nm, and a blue emission around 498 nm. The red and green emissions come from self-trapped excitons (STEs) and d-d transition of Zr(IV), respectively, which are caused by distortion of the [ZrCl6]2- octahedrons. The emission of blue is caused by thermally activated delayed fluorescence (TADF), which is similar to that of all-inorganic Cs2ZrCl6. The absolute photoluminescence quantum yield (PLQY) of the red and blue double emission is 83% and the absolute PLQY of green emission is 27%. With different combinations of ((C2H5)4N)2ZrCl6 samples, we achieve a variety of applications. First, a two-color luminescent anti-counterfeiting device was prepared using green ((C2H5)4N)2ZrCl6 powder. Secondly, using green and red ((C2H5)4N)2ZrCl6 powder, a white light-emitting diode (WLED) device with a color rendering index (CRI) of 95 was prepared. Finally, blue and green ((C2H5)4N)2ZrCl6 powder was used to achieve information encryption. Our work provides a potential set of multiexciton-emitting materials and is expected to expand the basic research and practical applications of multiexciton materials.