Realizing high CRI white organic light-emitting diodes via exciplex emission optimization

In this study, a series of three-color and four-color white organic light-emitting diodes (WOLEDs) were fabricated by controlling the movement of the exciplex emission recombination zone (RZ) and adjusting the intensity of yellow exciplex emission layers. These devices were based on blue exciplex emission layers (TCTA: TPBi), green exciplex emission layers (TCTA:PO-T2T), and yellow exciplex emission layers (TAPC:PO-T2T), in addition to red phosphorescent materials. The three-color WOLED demonstrated maximum power efficiency (PE) of 14.49 Im/W, current efficiency (CE) of 12.69 cd/A, and external quantum efficiency (EQE) of 5.58%. The four-color WOLEDs attained a high color rendering index (CRI) of 93 at 7V, with color coordinates of (0.3869, 0.4050). As far as we know, this represents one of the better data points where a CRI of 93 has been achieved in a WOLEDs using only one phosphorescent material.