Optimizing Peak Light-Emitting-Diode (LED) Wavelengths for Enhanced Color Performance and Visual Health in Blue Micro-LED Displays with Color-Conversion Layers

Abstract

This study examines the brightness conversion of green and red quantum dot (QD) color converters (QDCCs) utilizing blue-light panels at 437, 450, and 460 nm. The blue-light panels are separately tested under the same electrical power and optical power. The measurement results indicate that, as the wavelength of blue light becomes shorter, the conversion efficiency of QD emission increases, resulting in a higher brightness of the converted QDs. The QD emission conversion efficiency follows the order 437 > 450 > 460 nm. However, due to the lower energy of longer-wavelength blue light, more blue photons are generated per unit of optical power (radiant flux) compared to shorter-wavelength blue light. Therefore, the difference in the QD emission brightness resulting from the conversion is not significant. For instance, the QD emission brightness stimulated by 460 nm blue light is only slightly lower, approximately 4%, compared to that stimulated by 450 nm blue light. Considering that short-wavelength blue light can potentially damage biological tissues, especially the eyes, the development of longer-wavelength blue light will become a focal point for the next generation of QDbased micro-LED displays, which can be a promising technology for augmented reality (AR) and virtual reality (VR) display system. We computed the color gamut of QDCCs stimulated by blue light at 437, 450, and 460 nm; the yellow color filter (Y-CF)/QDCCs generated 115.7%, 112.4%, and 104.7% relative to National Television System Committee (NTSC). In addition, green and red color filters (G/R-CF)/QDCCs produce color gamut values of 117.0%, 114.2%, and 110.0% relative to NTSC, respectively. Finally, in the matter of color gamut coverage, it is evident that utilizing a blue excitation light source with a longer wavelength of 460 nm is essential for achieving full coverage of the blue region within the NTSC or BT2020 color gamut. It can effectively solve color shifts in the blue color.