摘要： Silica encapsulation effectively elevates the resistance of quantum dots (QDs) against water and oxygen. However, QDs-SiO2 composites present low thermal conductivity and strong thermal accumulation, leading to considerable fluorescent quenching of QDs in optoelectronic devices at high power. Here, a sandwich structural QDs-SiO2-BN nanoplate assembly material (QDs-SiO2-BNAs) is developed to reduce the thermal quenching and enhance the stability of QDs in LEDs. The QDs-SiO2-BNAs is fabricated by embedding QDs-SiO2 into the interlayer of layer-by-layer assembled BN nanoplates, and the BN nanoplates are pretreated by SiO2 encapsulation to strengthen the interaction with QDs-SiO2. This assembly structure endows the QDs with fast heat dissipation and double surface protection against air. The medium power QDs-converted LEDs (QD-LEDs) fabricated by directly on-chip packaging of the QDs-SiO2-BNAs gain 44.2 ℃ temperature reduction at 0.5 W in comparison with conventional QD-LEDs. After aging, the resulting QD-LEDs present degradation of only 1.2% under sustained driving for 250 hours. The QD-LEDs also pass the one-week reliability test at 85 ℃ / 85% RH with <±0.01 shift of the color coordinates, demonstrating the profound potential of the QDs-SiO2-BNAs in LED lighting and display applications.