Hybrid organic−inorganic and all-inorganic metal halide perovskite nanoparticles (PNPs) have shown their excellent characteristics for optoelectronic applications. We report an atmospheric process to embed formamidinium CH(NH2)2PbI3 (FAPbI3) PNPs in silica protective layer at room temperature (approximately 26 °C) employing (3-aminopropyl) triethoxysilane (APTES). The resulting perovskite nanocomposite (PNCs) achieved a high photoluminescence (PL) quantum yield of 58.0% and good stability under atmospheric moisture conditions. Moreover, the PNCs showed high PL intensity over 1 month of storage (approximately 26 °C) and more than 380 min of PNCs solutions in DI water. The studied near-infrared (NIR) light-emitting diode (LED) combined a NIR-emitting PNCs coating and a blue InGaN-based chip that exhibited a 788 nm electroluminescence spectrum of NIR-LEDs under 2.6 V. This may be a powerful tool to track of muscle and disabled patients in the detection of a blood vessel.
Annealing can usually inhibit the formation of an unstable brookite mesophase in the crystal structure, enhancing the growth of an anatase titanium dioxide (TiO 2 ) thin film. In this study, after a TiO 2 solution was prepared with and without a small amount (1 wt%) of the organic solvent dimethylformamide (DMF), TiO 2 films were obtained by dynamic spin-coating and were annealed at temperatures of 300, 500, and 700 °C. The structural and optical properties as well as the surface morphologies of the films were studied. The experimental results show that the TiO 2 film annealed at 500 °C exhibits a polycrystalline anatase and brookite multiphase and usefully inhibits the formation of the brookite mesophase when annealed at 700 °C. Moreover, adding the DMF effectively contributes to the formation of the polycrystalline phase at 300 °C. The compactness of the annealed TiO 2 film was improved by adding 1 wt% DMF, as shown by topographic images obtained by atomic force microscopy, leading to decreased transmittance and increased absorbance. The band gap (Eg) values of all the samples were also estimated. The variation of Eg was evidenced by the structural change and the redshift of the absorption edge.
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