Color Tuning of 2-Color Based White Organic Light-Emitting Diodes with Undoped Ultra-Thin Emission Layer

In the research of organic light-emitting diodes (OLEDs), the OLEDs that are fabricated via conventional doping methods have complicated structures and fabrication processes. To overcome these limitations, the ultra-thin emission layer (EML) method, which adopts a simple structure has been effectively used in the research of OLEDs. However, studies on white color OLEDs (WOLEDs) fabricated using the ultra-thin EML method are scarce. In this paper, we report the results of color tuning for the realization of WOLEDs based on an ultra-thin EML structure. The WOLEDs were fabricated and evaluated based on a two-color dopant system (sky-blue dopant and yellow dopant). The fabricated WOLEDs exhibited color coordinates of the International Commission on Illumination (CIE) 1931 from (0.287, 0.436) to (0.486, 0.483) according to the thickness ratio of the two dopants. This result suggests that the WOLEDs color tuned with multi-color dopants can be fabricated based on the ultra-thin EML method, and the development of WOLEDs with high efficiency and stability can be attained in the future.