In Situ Synthesis of Perovskite Quantum Dots/K₂SiF₆:Mn⁴⁺ Composites Enabled Efficient WLED Backlight for Wide Color Gamut Displays

Perovskite quantum dots (PQDs) and K 2 SiF 6:Mn 4+ (KSF) phosphor, renowned for high color purity, are prime candidates for emitters in white light-emitting diodes (WLEDs) for wide color gamut displays. To enhance the luminous efficacy (LE) and working stability of PQDs and KSF-integrated WLEDs, intricate fabrication processes, involving multiple post-treatments of PQDs and their blending with KSF, are often necessitated, inevitably compromising the production efficiency of the device. Herein, we develop a facile in situ synthesis approach that not only effectively passivates surface defects in PQDs and enhances their stability but also simplifies the fabrication process of PQDs and KSF-integrated WLEDs. Specifically, the silica-coated PQDs/KSF (PQDs/KSF@SiO 2 ) composite is synthesized via the in situ growth of MAPbBr 3 on an ethanol-treated KSF surface followed by SiO 2 encapsulation. The Pb–F coordination and SiO 2 encapsulation enable high luminescence intensity and simultaneously enhanced photothermal stability of PQDs. Eventually, the WLED based on PQDs/KSF@SiO 2 achieves a high LE of 83.11 lm·W –1 alongside a wide color gamut of 122.6% NTSC standard. Remarkably, the device exhibits excellent working stability, preserving its high LE virtually unaltered after 4 h of continuous operation. This work provides a facile approach to yield WLEDs with superior LE, wide color gamut, and exceptional working stability, positioning them ideally for practical display applications.