Effective Heat Dissipation of QD-Based WLEDs by Stacking QD Film on Heat-Conducting Phosphor-Sapphire Composite

Abstract

Quantum dots (QDs) are considered as promising color converters in the next-generation white light-emitting diodes (WLEDs) due to their tunable wavelength, high quantum yield, and excellent color rendering. However, the practical applications of QDs and QD composite films are severely hindered by their intrinsical drawbacks of thermal quenching and degradation. In this paper, we proposed an efficient heat dissipation approach to solve this issue by stacking a QD film on a heat-conducting phosphor-sapphire composite (PSC) plate. The PSC plate was prepared by printing and sintering YAG phosphor glass film on a sapphire substrate, which plays the roles of yellow converter and heat sink for the QD film. The luminescent performances of WLEDs were controlled by adjusting the QD contents. The high heat-conducting PSC plate provides an effective heat transfer channel for the QD film, which can sufficiently dissipate the heat to ambient air. Compared with the QD film stacked on the traditional phosphor-in-glass (PiG) and phosphor-in-silicone (PiS), the working temperatures of QD-PSC are reduced by 37 °C and 65 °C at 1000 mA, respectively. The QD-PSC-based WLEDs achieve stable luminescent performances for various operation times. The results demonstrate that the proposed approach can enhance the heat dissipation of QDs and realize stable white lighting.