Stability Breakthrough in Single-Layer PET-Encapsulated Perovskite Quantum Dot Backlighting Films: Synergistic Effect of the PbO Precursor and the Sapphire Substrate

Perovskite Quantum Dots (PQDs) have attracted significant attention in backlight display applications due to their excellent optoelectronic properties. However, their stability and large-scale production remain critical challenges to be addressed. In this study, PbO was used to replace PbBr2 as the lead source and optimized the Cs+ content to prepare PQDs glass composites. The optimized sample exhibited a high Photoluminescence Quantum Yield (PLQY) of 85%. Notably, its luminescence intensity retained 86% of its initial value after 40 days of aging under harsh conditions (60 °C and 8000 nit blue light). Furthermore, the innovative printing of perovskite glass powder on a sapphire substrate significantly improved the material’s stability, enabling 89% Photoluminescence (PL) intensity recovery after thermal cycling between 30 and 150 °C. The color gamut of CsPbBr3&CsPbBr1I2@glass@PET single-layer backlight film reached 130.4% of NTSC 1953 and 97.4% of Rec. 2020, and the color coordinate drift of the liquid crystal display (LCD) module was significantly reduced by combining with the sapphire substrate. Through the synergistic strategy of material optimization-substrate engineering, this study solved the stability problem and laid the foundation for the application of perovskite in backlight display.