Strategic use of dopants and device structure optimization for enhanced color gamut and efficiency in organic light-emitting diodes microdisplay applications

This study achieves enhanced color purity and efficiency in organic light-emitting diode (OLED) microdisplays. Considering the crucial role of the emitting material selection, particularly concerning color filters (CFs), four green and two red dopants were evaluated based on their photoluminescence spectra, with adjustments for a balanced RGB spectrum in white OLEDs. The impact of the device structure on the color gamut was explored by considering variations in the cavity length and its influence on the emission spectra. The results highlighted the importance of proper OLED design before applying CFs for increased color purity, indicating that the red, green, and blue emission spectra can be tailored through CFs, thereby affecting the color coordinates and luminance. When the OLED structure was designed to maintain a wide color gamut, the efficiency of OLED devices was influenced by the spectral characteristics of the dopants, even for the same color. In particular, the spectral characteristics of red dopants had a greater impact on efficiency compared to green dopants. Finally, an OLED microdisplay panel was demonstrated, achieving a high color gamut of 130.2% based on the sRGB standard through the strategic selection of dopants and CFs. • The combination of RGB dopants greatly impacts efficiency and color reproduction. • Reducing overlap between dopant PL and using color filters improves color accuracy. • A green dopant with a 530 nm peak optimizes both efficiency and color performance. • Red dopants should match the PL spectrum to the transmittance of the color filter.