Simultaneous enhancements on emissions from quantum dot and quantum well by Ag nanoparticles for color conversion

Abstract

Quantum dots (QDs) have been paid much attention on the color conversion for light-emitting diode (LED) in micro-display recently. However, it is hard to achieve high color conversion efficiency in a thin QD layer. In this paper, we fabricated silver nanoparticles (Ag NPs) with radii ranging mostly from 25 to 35 nm on a blue LED with a peak wavelength of 450 nm, then spin-coated QDs with a peak wavelength of 565 nm. Scanning electron microscopy, cathodoluminescence, photoluminescence (PL), and time-resolved PL measurements were performed. The PL emissions from quantum wells (QWs) of blue LED and QDs were enhanced by 10% and 32%, respectively, when the Ag NPs were included. The PL lifetimes of QWs and QDs were reduced by 10 and 6 times, respectively, compared to their initial states. Finite difference time domain software and the perturbation method were used to simulate the PL measurements and variable separation. It was concluded that the coupling of QDs and QWs with localized surface plasmon improves the external quantum efficiency and enhances the spontaneous emission rate in both QWs and QDs. This paper provides a new idea for designing high-efficiency color conversion micro-LED.