No abstract

Traditional backlights are designed with new dot patterns, and then injection molding, laser beam fabrication, or UV (Ultraviolet) roll-to-plate imprinting is used to apply dot patterns to a light guide plate—the process consumes considerable time and resources. Therefore, we propose a novel light guide design that does not use a dot pattern. We designed an asymmetric intensity distribution of mini-LEDs (Light Emitting Diode) and a light guide plate with a fully printed diffusion reflection on the bottom surface for a planar illuminator. The design rules for the proposed architecture are described in this paper. The archetype design with a 152.4 mm circular down-light has a diameter of 143 mm for the planar light source module. The experiment achieved a total efficiency of 85% and uniformity of 92.6%.

We demonstrate excellent color quality of liquid-type white light-emitting diodes (WLEDs) using a combination of green light-emitting CsPbBr3 and red light-emitting CdSe/ZnS quantum dots (QDs). Previously, we reported red (CsPbBr1.2I1.8) and green (CsPbBr3) perovskite QDs (PQDs)-based WLEDs with high color gamut, which manifested fast anion exchange and stability issues. Herein, the replacement of red PQDs with CdSe/ZnS QDs has resolved the aforementioned problems effectively and improved both stability and efficiency. Further, the proposed liquid-type device possesses outstanding color gamut performance (132% of National Television System Committee and 99% of Rec. 2020). It also shows a high efficiency of 66 lm/W and an excellent long-term operation stability for over 1000 h.

To realize high-efficiency AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs), enhancing their light-extraction efficiency (LEE) is crucial. This paper proposes an aluminum-based sidewall reflector structure that could replace the conventional ceramic-based packaging method. We design optimization simulations and experimental results demonstrated the light power output could be enhanced 18.38% of DUV-LEDs packaged with the aluminum-based sidewall.

This study presents a novel method for estimating the phosphor conversion efficiency of white light-emitting diodes (WLEDs) with different ratios of phosphors. Numerous attempts have been made for predicting the phosphor conversion efficiency of WLEDs using Monte Carlo ray tracing and the Mie scattering theory. However, because efficiency depends on the phosphor concentration, obtaining a tight match between this model and the experimental results remains a major challenge. An accurate prediction depends on various parameters, including particle size, morphology, and packaging process criteria. Therefore, we developed an efficient model that can successfully correlate the total absorption ratio to the phosphor concentration using a simple equation for estimating the spectra and lumen output. The novel and efficient method proposed here can accelerate WLED development by reducing costs and saving fabrication time.