Enhancement of Optical Performance for Quantum Dot White LEDs with Semi-Shperical Lens Packaging Structure using SiO2 nanoparticles

Abstract

The scattering effect is profitable to improve the optical performance of quantum dot (QD) white light-emitting diodes (LEDs), however, most of previous studies were focused on the planar packaging structure for reducing the total internal reflection loss. In this report, SiO2 nanoparticles were doped into QD-silicone encapsulation of LEDs so as to exploit their strong scattering effect, which were demonstrated by the measurements of SiO2-nanoparticles-only films. The LEDs with semi-spherical lens packaging (SSLP) structure were used in this study. Results show that the radiant and luminous efficacy of QD white LEDs with optimized SiO2 nanoparticle concentration (0.1 wt%) show 5.07% and 11.08% increases, respectively, compared to the conventional structure. The spectra energy analysis reveals that the scattering effect enhances the utilization of blue light emitted from chips and reduces the back-emission loss of light excited from QDs. Moreover, the correlated color temperature (CCT) decreases as the concentration of SiO2 nanoparticles increases, which is potential to save QD usage when achieving the same CCT. Consequently, this study provides a better understanding on the scattering effect in QD white LEDs with SSLP structure, which is essential for improving their optical efficiency.