P‐145: Oxide Encapsulation of CsPbBr3 Nanocrystals to Enhance the Optical Efficiency and PLQY for LEDs Through Transition Dipole Alignments

The efficiency of perovskite light‐emitting diodes (PeLEDs) is often hindered by the degradation of quantum dots (QDs) due to interactions with air, moisture, and substrate. To address this, we demonstrate that encapsulating CsPbBr3 nanocrystals with a silica (SiO2) layer significantly enhances their stability and optical performance. Silica‐encapsulated CsPbBr 3 @SiO 2 retained 76.8% of its initial photoluminescence (PL) intensity after two weeks of exposure to light and moisture, compared to only 34% for uncoated CsPbBr 3 Furthermore, oxide encapsulation improves light extraction by reducing total internal reflection within the active layer, directing emissions towards the escape cone. The transition dipole moment (TDM) angle for CsPbBr 3 @SiO 2 was measured to be ~32°, indicating a tendency towards isotropic emission, which enhances outcoupling efficiency. These findings suggest that oxide encapsulation is a promising strategy for improving the operational stability and optical efficiency of PeLEDs.