A flexible transparent organic light-emitting display with high-transmittance cathode and high-contrast electrochromic shutter

In this work, we studied a flexible transparent organic light-emitting display (TOLED) with a stacking magnesium (Mg) and silver (Ag) alloys (Mg:Ag)/1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN)/indium zinc oxide (IZO) transparent cathode and combined it with a high-contrast flexible electrochromic shutter (ECS). The transmittance of the segment-type flexible TOLED based on an 84.5% transparent polyimide substrate was 64.2%. The sheet resistance of the TOLED cathode used in this study was 22.94 Ω/sq, which was close to the value needed in OLED cathode applications. The flexible ECS was composed of two color-changing layers, namely, a hybrid electrochromic layer and a color-changing gel electrolyte layer, and the contrast ratio of the flexible ECS was 24.5. The ECS blocked background light and increased the contrast ratio of the flexible TOLED panel. The flexible OLED and flexible ECS were bonded with an optical clear adhesive (OCA) film, and the transmittance of the entire structure was 52.3%. After 2,000 folding repetitions of the integral sample with a folding radius of 3 cm, the ECS maintained its coloration characteristics, and TOLED retained a brightness level of 200 nits.