Exploiting p-Type Delayed Fluorescence in Hybrid White OLEDs: Breaking the Trade-off between High Device Efficiency and Long Lifetime.

Abstract

Despite that the majority of practical organic light-emitting diodes (OLEDs) still rely on blue fluorophors with low triplet (T1) for creating blue light, hybrid white OLEDs based on low T1 blue fluorophors are still much lagged behind in power efficiency. Here, "ideal" hybrid WOLEDs with recorded efficiency as well as low roll-off, good color-stability and long lifetime were realized by utilizing the bipolar mixed materials as the host of green phosphor as well as the spacer to reduce T1 trap, while blue fluorophors with p-type delayed fluorescence to recycle the trapped T1. An electron transport material with both high electron mobility and good exciton confinement ability was used to boost the TTA efficiency. Hybrid WOLEDs with maximum current efficiency, external quantum efficiency and power efficiency of 49.6 cd/A, 19.1%, and 49.3 lm/W, respectively, together with a high color rendering index of 80 and a half lifetime of over 7000 h at an initial luminescence of 1000 cd/m(2) were realized, manifesting the high potential of the strategy.