Dual Light Emission of CsSnI₃-Based Powders Synthesized via a Mechanochemical Process

Lead toxicity has hindered the wide applications of lead halide perovskites in optoelectronics and bioimaging. A significant amount of effort has been made to synthesize lead-free halide perovskites as alternatives to lead halide perovskites. In this work, we demonstrate the feasibility of synthesizing CsSnI₃-based powders mechanochemically with dual light emissions under ambient conditions from CsI and SnI₂ powders. The formed CsSnI₃-based powders are divided into CsSnI₃-dominated powders and CsSnI₃-contained powders. Under the excitation of ultraviolet light of 365 nm in wavelength, the CsSnI₃-dominated powders emit green light with a wavelength centered at 540 nm, and the CsSnI₃-contained powders emit orange light with a wavelength centered at 608 nm. Both the CsSnI₃-dominated and CsSnI₃-contained powders exhibit infrared emission with the peak emission wavelengths centered at 916 nm and 925 nm, respectively, under a laser of 785 nm in wavelength. From the absorbance spectra, we obtain bandgaps of 2.32 eV and 2.08 eV for the CsSnI₃-dominated and CsSnI₃-contained powders, respectively. The CsSnI₃-contained powders exhibit the characteristics of thermal quenching and photoelectrical response under white light.