In Situ Green Preparation of Highly Stable CsPbBr3–Polyimide Films for Flexible Liquid Crystal Displays

Abstract Inorganic lead halide perovskite quantum dots (QDs) CsPbX 3 (X = Cl, Br, or I) with superior optical and electronic properties are regarded as excellent materials for various optoelectronic devices. However, their instability significantly hinders their practical applications. Herein, composite films of CsPbBr 3 QDs and polyimide (CsPbBr 3 @PI) are prepared using an in situ green synthesis method without other ligands and anti‐solvents. This strategy allows the formation of CsPbBr 3 QDs and polymerization of polyimide monomers to occur simultaneously, which encapsulates the CsPbBr 3 QDs with a protective PI layer. The CsPbBr 3 @PI film has narrowband green emission and excellent stability against air, water, and light. The emission intensity of a CsPbBr 3 @PI film is maintained at 93% and 90% of the initial intensity after exposure to air for 43 days and immersion in water for 14 days, respectively. In addition, the water contact angle is 105°, indicating that the film has good hydrophobicity. Surprisingly, the film is not broken after repeated bending (1 250 times), and its emission intensity is almost unchanged, which illustrates that the film has excellent flexibility. The good performance of the obtained CsPbBr 3 @PI films indicates their potential as a backlight source for flexible liquid crystal display applications.