Improving the contrast ratio of OLED displays: An analysis of various techniques

Organic light emitting diode (OLED) based displays have matured into commercial products. However, while we consider OLED for a low-cost high-resolution and high-contrast displays with a long life span, still there are performance gaps. This review addresses various techniques used for increasing the ambient contrast ratio of OLED displays. There are techniques which are integral to the OLED device, such as black cathodes and absorbing transport layers. In contrast, anti-reflection (AR) coatings and circular polarizer are applied externally to the device. This review provides a brief overview of each technique along with a discussion on its merits and demerits. The choice of a particular contrast enhancement technique for a display depends on the ambient where the same is intended to be used. Accordingly, for indoor and outdoor applications, the best possible methods are suggested.

► Detailed explanation of ambient contrast ratio (CR) in OLEDs given.
► Several techniques used for increasing the ambient contrast ratio are discussed and compared.
► Concluded that a combination of these techniques are required for achieving high CR.