ABSTRACT
Tin-based perovskites are becoming promising alternatives to lead-based perovskites with eco-friendly merit and tantalizing photophysical properties. Unfortunately, the lack of facile, low-cost synthesis approaches associated with extremely poor stability greatly restrict their practical applications. Herein, a facile room-temperature "coprecipitation" method utilizing ethanol (EtOH) solvent and salicylic acid (SA) additive is proposed for synthesizing highly stable cubic phase CsSnBr3 perovskite. Experimental results show that ethanol solvent and SA additive can not only effectively prevent the oxidation of Sn2+ during the synthesis processes but also stabilize the as-synthesized CsSnBr3 perovskite. These are mainly ascribed to the protection effect of ethanol and SA, which are attached on the surface of CsSnBr3 perovskite by coordinating with Br- and Sn2+ ions, respectively. As a result, CsSnBr3 perovskite can be obtained in open air and exhibits exceptional oxygen resistibility under moist air conditions (temperature: 24.2-25.8 °C; relative humidity: 63-78%). Absorption remains unchanged and photoluminescence (PL) intensity is vastly maintained (â¼69%) after storage for 10 days, better than bulk CsSnBr3 perovskite film synthesized by spin-coating method whose PL intensity is decreased to 43% after storage for 12 h. This work represents a step toward stable tin-based perovskite by a facile and low-cost strategy.
ABSTRACT
The rational design of multifunctional inorganic pigments relies on the manipulation of ionic valence and local surroundings of a chromophore in structurally and chemically habitable hosts. To date, the development of environmentally benign and intense violet/purple pigments is still a challenge. Here we report a family of A3-xMnxTeO6 and A3-2xMnxLixTeO6 (A = Zn, Mg; x = 0.01-0.15) pigments colored by site-selective Mn2+O4 yellow and Mn3+O5-6 violet chromophores. Zn2.9Mn0.1TeO6 is intense bright yellow, comparable with commercial BiVO4, and has better near-infrared reflectivity (â¼89%) in comparison to commercial TiO2. The codoped Li+ "activator" generates holes and charge-balanced Mn3+ (Mn3+O5-6), realizing a color transformation from yellow to the bright violet pigments of A3-2xMnxLixTeO6. The most vivid Mg2.8Mn0.1Li0.1TeO6 is probably the best violet pigment known to date, exhibits excellent chemical and thermodynamic stability, and demonstrates pressure-dependent stability up to 5-7 GPa, before a (reversible) phase transition to pink. Theoretical calculations revealed the correlation between site-preference occupancy and chromophore motifs and predicted a wide color gamut of pigments in Zn3TeO6-hosted 3d transition-metal ions other than manganese.
ABSTRACT
Here, we present a single atomic supersaturated recrystallization method to synthesize the green-emitting CsPbBr3-Cs4PbBr6 perovskite composites in solid state with the highest PLQY of 40.8% in pure polar solvent. The component, morphology, and optical properties of the microcrystals can be tuned by varying growth time, the content of ammonium bromide, and bromine source. The developed method provides a new route to large-scale synthesize high quality perovskite composites emitters for light-emitting diodes.
ABSTRACT
The microscale composite structure strategy of embedding CsPbBr3 nanocrystals (NCs) in the microscale Cs4PbBr6 matrix (CPB113/CPB416) has successfully demonstrated its ability to resolve the fluorescence quenching of perovskite NCs in the solid agglomeration state due to the loss of quantum confinement. Unfortunately, the controllable synthesis of monodisperse nanoscale composites with bright emission in the solid state remains a great challenge. Here, we present for the first time a novel supersaturated recrystallization process to controllably synthesize monodisperse CPB113/CPB416 composite NCs with bright emission in the solid form, where CsPbBr3 NCs were uniformly embedded in the nano hexagonal Cs4PbBr6 matrix. The existence of 2-methylimidazole (MeIm) not only can control the composition rate of CsPbBr3 to Cs4PbBr6, the size and dispersity of CsPbBr3 in the composite NCs but can also help controllably obtain the monodisperse and hexagonal Cs4PbBr6 matrix. The as-prepared composite structure can effectively prevent CsPbBr3 fluorescence quenching and make the composite NCs have a high photoluminescence quantum yield (PLQY) of 83%. In addition, we obtained tunable blue to red emitting composite NCs by varying the halide salts.
