Highly efficient CsPbBr3@glass@polyurethane composite film as flexible liquid crystal display backlight

Abstract

Inorganic lead halide perovskite quantum dots (CsPbX₃ QDs (X = Cl, Br, or I)) have attracted more and more attention due to their high absorption coefficient, narrow emission band, high quantum efficiency, and tunable emission wavelength. However, CsPbX₃ QDs are decomposed when exposed to bright light, heat, moisture, etc., which leads to severe luminous attenuation and limits their commercial application. In this paper, CsPbBr₃@glass materials were successfully synthesized by a one-step self-crystallization method, including melting, quenching and heat treatment processes. The stability of CsPbBr₃ QDs was improved by embedding CsPbBr₃ QDs into zinc-borosilicate glass. Then, the CsPbBr₃@glass was combined with polyurethane (PU) to form a flexible composite luminescent film CsPbBr₃@glass@PU. This strategy enables the transformation of rigid perovskite quantum dot glass into flexible luminescent film materials and further improves the photoluminescence quantum yield (PLQY) from 50.5% to 70.2%. The flexible film has good tensile properties, and its length can be strained 5 times as long as the original length. Finally, a white LED was encapsulated by combining CsPbBr₃@glass@PU film and red phosphor K₂SiF₆:Mn⁴⁺ with a blue LED chip. The good performance of the obtained CsPbBr₃@glass@PU film indicates that it has potential application in flexible liquid crystal displays (LCDs) as a backlight source.