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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. 

Blue emitting Sn-based lead-free halide perovskite nanocrystals (NCs) are considered to be a promising material in lighting and displays. However, industrialised fabrication of blue-emitting NCs still remains a significant challenge due to the use of toxic solvents and optical instability, not mentioning in large-scale synthesis. In this work, a green-route synthesis of blue-emitting lead-free halide perovskite Cs 2 SnCl 6 powders is developed, in which deionized water with a small amount of inorganic acid is used as the solvent and the synthesis of the Cs 2 SnCl 6 powders is achieved on a microfluidic platform. Using the Cs 2 SnCl 6 powders, we prepare Cs 2 SnCl 6 NCs via an ultrasonication process. Changing the volume ratio of the ligands (oleic acid to oleylamine) can alter the photoluminescence (PL) characteristics of the prepared NCs, including the PL-peak wavelength, PL-peak intensity and quantum yield. The highest photoluminescence quantum yield (PLQY) of 13.4% is achieved by the Cs 2 SnCl 6 NCs prepared with the volume ratio of oleic acid to oleylamine of 40 μL to 10 μL. A long-term PL stability test demonstrates that the as-synthesized Cs 2 SnCl 6 NCs can retain a stable PLQY over a period of 60 days. This work opens up a new path for a large-scale green-route synthesis of blue-emitting Sn-based lead-free NCs, such as Cs 2 SnX 6 (Cl, Br and I), towards their applications in optoelectronics. 

Abstract In this work, we develop an environmental-friendly approach to produce organic-inorganic hybrid MAPbBr 3 (MA = CH 3 NH 3 ) perovskite nanocrystals (PeNCs) and PMMA-MAPbBr 3 NC films with excellent compression-resistant PL characteristics. Deionized water is used as the solvent to synthesize MAPbBr 3 powder instead of conventionally-used hazardous organic solvents. The MAPbBr 3 PeNCs derived from the MAPbBr 3 powder exhibit a high photoluminescence quantum yield (PLQY) of 93.86%. Poly(methyl methacrylate) (PMMA)-MAPbBr 3 NC films made from the MAPbBr 3 PeNCs retain ∼97% and ∼91% of initial PL intensity after 720 h aging in ambient environment at 50 °C and 70 °C, respectively. The PMMA-MAPbBr 3 NC films also exhibit compression-resistant photoluminescent characteristics in contrast to the PMMA-CsPbBr 3 NC films under a compressive stress of 1.6 MPa. The PMMA-MAPbBr 3 NC film integrated with a red emissive film and a blue light emitting source achieves an LCD backlight of ∼114% color gamut of National Television System Committee (NTSC) 1953 standard.