Lead-Free All-Inorganic Indium Chloride Perovskite Variant Nanocrystals for Efficient Luminescence

Lead-free halide perovskites and their variants have attracted great attention due to their non-toxicity and good photophysical properties. Here, a series of undoped and antimony-doped all-inorganic, 0D, indium-based perovskite variant nanocrystals (NCs): (RbxCs1-x)(3)InCl6 and (RbxCs1-x)(3)InCl6:Sb (0 <= x <= 1) NCs, is reported. Among them, Sb-doped NCs exhibit green emission. Mixing Rb-Cs NCs show the higher photoluminescence (PL) quantum efficiency (PLQE) and better stability than unalloyed NCs (x = 0 or 1). The effect of crystal size on PL property of (Rb0.75Cs0.25)(3)InCl6:Sb is analyzed in detail. More interestingly, In-based perovskite variant NCs containing coordinated water are successfully synthesized by a two-step method (variable temperature hot injection and saturated steam post treatment). The best PLQE of Sb-doped Cs2InCl5(H2O) NCs reaches 95.5%, which is a new PLQE record for yellow emissive lead-free perovskite and variant NCs. In addition, the emission mechanism is further clarified by temperature-dependent PL and femtosecond transient absorption techniques.