Thermal and Optical Analysis of Quantum-Dot-Converted White LEDs in Harsh Environments

Abstract

Quantum-dot-converted white LEDs (QD-WLEDs) are promising in both lighting and display applications owing to their high luminous efficiency (LE) and high color-rendering index (CRI). However, their working lifetime is severely limited by the poor reliability of QDs and the LED package. In this work, the variation in photothermal parameters in QD-WLEDs during aging was investigated, and the effect of QDs and the LED package on the optical performance of QD-WLEDs was analyzed. First, the optical properties of phosphor–silicone, QD–silicone, and silicone were measured during the 524 h aging process at 80 °C and 100 °C, respectively. QD-WLEDs with high optical performance were packaged and aged under the same conditions to investigate the variation in their optical parameters and analyze the trends of their CRIs and correlated color temperatures (CCTs). According to the experimental results and the calculation models of the spectra, it was found that the changes in optical parameters are mainly caused by the degradation of QDs, and the aging of QDs has different effects on the CRI and CCT. The analysis of the energy-transfer process shows that the decrease in luminous flux of QD-WLEDs during the aging process is mainly caused by the aging of silicone. Based on optical and thermal analysis, this study proposed different optimization strategies for optical quality and lifetime in the LED design process.