Study on optical performance and reliability of white light-emitting diodes by quantum-dots/epoxy composite particles

Quantum-dots (QDs) have attracted great attention for their excellent advantages, but the bad reliability of heat and water limits its application. So QDs/epoxy composite particles are proposed to improve stability of QDs and serve for direct package in industry. The composite particles were mainly fabricated by mechanical grinding process, and then packaged for application. The reliability of the composite particle film shows greater performance than the pure QDs/PDMS film. Under the environment of humidity of 85% and temperature of 85 degrees C, the luminous efficiency of the device with composite particle film rose mildly in the first 8 h and could maintain 100% after 92 h. But the luminous efficiency of the device with pure QDs/PDMS film kept decreasing with the aging time. After aging for 160 h, the luminous efficiency of the device with pure QDs/PDMS film decreased 64.1%, but the luminous efficiency of device with the composite particle film only decreased 2.5%, showing the better reliability performance. Besides, the device with composite particle film only scarifies luminous flux of 5.11% and 6.41% compared with the pure QDs/PDMS film in the same QD concentration and at similar CCT, respectively. It can be concluded that the fabrication of QDs/epoxy composite particles is a good way to improve the stability of QDs in the actual application with a small sacrifice of luminous efficiency.