Balancing efficiency and color gamut in white organic light-emitting diodes for microdisplay applications by microcavity and color filter conditions

Color filters are applied to white organic light-emitting diode microdisplays to generate red, green, and blue subpixels. By incorporating a microcavity structure, both the efficiency and the color gamut of the device can be significantly improved. Although the length of the cavity can be adjusted for each subpixel, the optical properties of the top electrodes remain consistent across all subpixels. The focus of this study was on optimizing the microcavity structure to accurately realize the colors of each subpixel in white organic light-emitting diodes while accounting for the transmittance characteristics of the color filters. While higher electrode reflectivity improved the color gamut, the optimal electrode structure for efficiency varied for each subpixel. In the case of color filters, increasing the thickness tends to improve the color gamut but reduces efficiency. Therefore, subpixel structures that optimize both the efficiency and color gamut by balancing these factors were investigated in this study. As the red, green, and blue ratio within the emitting layer affects the electroluminescence spectrum of the organic light-emitting diode device, the composition of the emitting layer was also investigated to optimize the color gamut.