Fig. 5. Water and thermal stability characterization. (a) Photographs of blue (CsPbClBr2–PS), green (CsPbBr3–PS) and red (CsPbBrI2–PS) composite films in water under UV irradiation after two months of water immersion. (b and c) Each film sample was cut into two pieces in the beginning, with one piece stored in air and the other immersed in water. Photographs of the two pieces in one frame taken (b) at the beginning and (c) after two months. (d–f) Temperature-dependent PL intensities of (d) blue (CsPbClBr2–PS), (e) green (CsPbBr3–PS), and (f) red (CsPbBrI2–PS) composites. The red solid line refers to the heating process and the blue dashed line refers to the cooling process. (g–i) Comparison of PL emission spectra and relative PL intensities of (g) blue (CsPbClBr2–PS), (h) green (CsPbBr3–PS) and (i) red (CsPbBrI2–PS) composites before (black line) and after (red line) boiling water treatment. Inset shows the photos of the unboiled piece (top) and boiled piece (bottom) originally cut from one sample.
