Crystallization engineering in PVDF enables ultrastable and highly efficient CsPbBr3 quantum dots film for wide color gamut Mini-LED backlight

The polymeric composite films incorporating inorganic lead halide perovskite quantum dots (CsPbX3 QDs, X = Cl, Br or I) are promising color conversion layers for wide gamut display devices such as Mini-LED backlightbased televisions. However, the relatively low emission efficiency and poor stability of these composite films present significant challenges for practical applications. In this study, we present a novel low-temperature in-situ crystallization strategy to prepare CsPbBr3/PVDF composite film through a rational designed of precursor, solvent and polymer structure. The strong interaction between PVDF and perovskite QDs via Lewis acid-base interaction allows for precise control over the crystallization and passivation of perovskite QDs. The optimized CsPbBr3/PVDF film exhibits bright emission with a photoluminescence quantum yield (PLQY) of up to 70 %, surpassing those of other CsPbBr3/polymers counterparts. Furthermore, the films demonstrate remarkable stability, retaining over 90 % of their original PLQY even after 50 days of aging under various environmental conditions such as exposure to air, immersion in water and blue light irradiation. By integrating the green and red emissive CsPbX3/PVDF films with blue Mini-LEDs, we successfully fabricate a prototype liquid crystal display (LCD) with an outstanding wide color gamut (128 % of NTSC 1931). These performances outperform that of commercial white-LED-based LCDs, highlighting the immense potential of CsPbX3/PVDF for high-definition display applications in the future.