Red exciplex and its application in high CRI all-exciplex fluorescent white organic light emitting diodes

Highly efficient red exciplex with the emission peak of ∼600 nm and the maximum external quantum efficiency (EQE) of 5.7% was realized with the application of Ir(ppy)3. Then a series of all-exciplex emission white organic light emitting diodes (WOLEDs) were achieved with complementary color by combining red exciplex of Ir(ppy)3:PO-T2T and blue exciplex of mCP:PO-T2T. The WOLEDs based all-exciplex could maintain a high color rendering index (CRI) (>80) value under different voltages and the highest CRI reach to 93. Meantime, a exceed 5% EQE fluorescent efficiency upper limit were obtained with maximum current efficiency, power efficiency and EQE of 13.8 cd/A, 11.6 lm/W and 6.4%, respectively. The broad emission bands of red/blue exciplex, efficient triplet exciton harvest and elaborately spectral modulation are responsible for high CRI and efficiency with all-exciplex WOLEDs.