Room temperature synthesis of nanocomposite thin films with embedded Cs2AgIn0.9Bi0.1Cl6 lead-free double perovskite nanocrystals with long-term water stability, wide range pH tolerance, and high quantum yield

Abstract

The synthesis of Cs₂AgIn_0.9Bi_0.1Cl₆ nanocrystals was achieved at room temperature under ambient conditions using the ligand-assisted reprecipitation (LARP) method. The synthesized NCs exhibit bright orange emission when excited at 375 nm and have broad photoluminescence (PL) emission spectra with a maximum of 630 nm. A photoluminescence quantum yield (PLQY) of 36% was observed in these NCs without any polymer coatings. Polystyrene (PS), and poly (methyl methacrylate) (PMMA) were used to enhance the water stability and PLQY values up to 64%. Nanocomposite thin films with these polymer encapsulations exhibit good thermal stability up to at least 353 K and high quantum yields. PMMA-coated NCs showed long-term water stability for at least 4 months. The composites remain photostable when in contact with water for at least 120 min under continuous 365 nm UV illumination at 1 mW cm⁻². Due to their excellent optical properties, aqueous stability, and wide range pH tolerance, these nanocomposite thin films could be employed for a variety of biological applications.