Long-Persistent Luminescence from Double Self-Defect States in Undoped Cs3In2Cl9 Nanocrystals for Bioimaging and Display Technologies

A long-persistent luminescence (LPL) material based on lead-free perovskite nanocrystals (Cs3In2Cl9 NCs) was synthesized by hot injection at 175 °C. Based on X-ray diffraction and theoretical calculations, the crystal structure of Cs3In2Cl9 NCs belongs to the trigonal space group R3̅c. The Cs3In2Cl9 NC powder emits white light at a peak wavelength of 430 nm with a full width at half maximum (FWHM) of about 118 nm and a photoluminescence quantum yield (PLQY) of 26.3%. The lifetime of its LPL is ∼1 s at 300 K and ∼10 s at 77 K. To explain the mechanism of LPL in Cs3In2Cl9, double self-defect states (DSDS) were proposed. To the best of our knowledge, this is the first time to obtain LPL in undoped lead-free perovskites. It promotes the application of perovskites and the explanation of the mechanism of LPL.