Solution growth and optical properties of lead-free highly efficient green-emitting [Emim]4[Cu4I8] single crystals with 0D structure

Recently, zero-dimensional organic-inorganic lead halides perovskites have garnered considerable attention due to their exceptional photoelectric performance, however, the toxicity of lead makes their prolonged application difficult. In this work, centimeter-scale lead-free zero-dimensional perovskites [Emim]4 [Cu4I8] single crystals were grown by the solution evaporation method. The structure and composition of the crystals were analyzed using XRD, EDS, XPS, etc. The energy band structure and the partial density of states (PDOS) were calculated by using the density functional theory (DFT) based on the PBE hybrid functional. The excitation and emission spectra of the crystal material were determined under different conditions. The luminescence mechanism and fluorescence lifetime of the crystal were also analyzed, and the green emitting of the crystal was caused by self-trapped excitons (STEs). Interestingly, the compound showed excellent responsiveness to X-rays, which is rarely reported in organic-inorganic hybrid copper-based halides. Overall, [Emim]4 [Cu4I8] demonstrates its good potential.