Color Tunable Three Terminal (3-T) Vertically Stacked Tandem Organic Electroluminescent Devices

Traditional full-color displays typically use a pixel layout with three side-by-side subpixels emitting red (R), green (G), and blue (B) colors. However, this configuration limits the resolution especially in augmented reality (AR) and virtual reality (VR) applications. To address the issue of low pixel density in display technology, this study demonstrated vertically stacked three-terminal (3-T) bottom-emitting tandem OLEDs (sOLED). These OLEDs offer color tunability, facilitated by individually controlled colour units. This study demonstrates two combinations: G+B and R+G. Incorporating three generations of OLED's materials phosphorescent (R), thermally activated delayed fluorescence (TADF) (G), and hyperfluorescent (B). The OLEDs achieve maximum current efficiencies of approximately 11 cd/A, 52.4 cd/A, and 40.7 cd/A for R, G, and B, respectively, in their respective tandem configurations. A wide range of colors can be achieved by blending G+B and R+G color spectrum by adjusting the voltage of independent color unit. The optimal mix results in a fine cyan color with CIE coordinates (0.273,0.5) in G+B sOLED and a warm white with CIE coordinates (0.416,0.518)in R+G sOLED. This work demonstrate a better performing 3-T sOLED utilizing three different generations OLED materials, offering an individual control within a single pixel providing enhanced pixel density for display technology.