Ambient contrast ratio of quantum-dot color-converted micro-LED displays

Pixelated quantum dot color conversion layer (PQDCCL) is the most promising approach to realize a full-color micro-LED display. However, the QD excitation by ambient light has non-negligible impact on the ambient contrast ratio (ACR) and the display readability, and the ACR issue of color-converted micro-LED display has not been fully explored before. In this paper, the theoretical models of unpixelated monochromatic and pixelated polychromatic QDCCLs (UP/PQDCCL) are established to quantificationally analyze the ACR of a micro-LED display, which is further demonstrated by both ray-tracing simulation and experimental test. The simulation and theoretical results are highly consistent, and the average deviation is only 6.73%. In terms of experimental verification, the ACR indices are between 19.90 and 36.20 for the prepared UP/PQDCCLs that are obtained by photolithography technique and measured under the indoor ambient light of 500 lx and the luminance of the micro-LED screen of 1000 nits. The experimental, simulation, and theoretical results are fully compared and analyzed to show the application prospect of the proposed model in QD-based micro-LED displays. More importantly, this model could provide theoretical support and proof for the ACR estimation of self-luminous color-converted displays.