Shape optimization of quantum-dot caps for high color-rendering white light-emitting diodes studied by optical simulation

Abstract

Conventional white lightings based on light-emitting diodes (LEDs) lack deep red, which is responsible for their low color rendering index (CRI). To apply red quantum-dot (QD) caps is one way to improve the color-rendering property of white LEDs. Red QD caps were fabricated using CdSe/ZnS QDs in the acrylic resin matrix and applied to conventional white LED lighting, which clearly showed a significant increase in the CRI, especially R9 associated with the strong red. Optical simulation was carried out to find out the optimized structure of the QD caps. The CRI increased while the optical efficiency decreased as the color conversion efficiency increased, which suggested that there should be a compromise between the two properties. It was found that to form a non-absorbing optical cavity in the QD cap was an effective way to achieve high CRI values while maintaining a moderately good optical efficiency.