Ultrastable PVB films-protected CsPbBr3/Cs4PbBr6 perovskites with high color purity for nearing Rec. 2020 standard.

• HPSs@PVB films were successfully prepared. • HPSs possess superior optical performance after PVB coating. • The thermal cyclability, water and UV resistance of HPSs@PVB films are excellent. • The color gamut is as wide as 126% based on the high color purity HPSs@PVB device, reaching 94% of Rec. 2020. Here, polyvinyl butyral (PVB) films-protected CsPbBr 3 /Cs 4 PbBr 6 halide perovskite solids (HPSs) were successfully synthesized. The optical properties and structure of HPSs@PVB were studied, finding the photoluminescence quantum yields (PLQYs) of this novel composite material is as high as 60.4%. More importantly, HPSs@PVB has excellent thermal cyclability, water and ultraviolet (UV) resistance. In addition, HPSs@PVB was further applied to light emitting diodes (LEDs) and displays. By combining green-emitting HPSs@PVB and red-emitting CsPbBrI 2 NCs@PVB with InGaN 460 nm blue chip, white light emitting diode (WLED) device can be successfully fabricated. And the device exhibits good stability and the color gamut is as wide as 126%, reaching 94% of Rec. 2020. This work proposes a simple approach to solve the challenging stability issue of perovskite nanocrystals (NCs), having a positive implication for their practical application in LEDs and display backlights. [ABSTRACT FROM AUTHOR]