Realization of high-color-quality white-by-blue organic light-emitting diodes with yellow and red phosphor films

In this study, we realized white-by-blue organic light-emitting diodes (OLED) combined with free-standing yellow (Y) and red (R) phosphor films (PFs) as color-converting materials. The process involves conventional blue OLEDs as a light source and Y and R PFs as the color-conversion layer (CCL) via a physically attached method. The CCL of the Y and R PFs is used according to the various concentrations applied and the color rendering thickness by control of the wavelength. Several types of white OLEDs (WOLEDs) from a Y PF with a blue OLED or R/Y PFs with a blue OLED are fabricated with a CCL to produce good color rendering index (CRI) values. Also, the color performance of the devices is stable. The CRI values of a WOLED with R/Y PFs were improved to nearly 90 and the correlated color temperatures (CCTs) ranged from cool white to neutral/warm white between 5260 K and 4100 K. Moreover, the color fidelity score (Rf) and color gamut score (Rg) values are in good agreement with the reference sources.