Suppressing the Undesirable Energy Loss in Solution-Processed Hyperfluorescent OLEDs Employing BODIPY-Based Hybridized Local and Charge-Transfer Emitter

Hyperfluorescent organic light-emitting diodes (HF-OLEDs) approach has made it possible to achieve excellent device performance and color purity with low roll-off using noble-metal-free pure organic emitter. Despite significant progress, the performance of HF-OLEDs is still unsatisfactory due to the existence of a competitive dexter energy transfer (DET) pathway. In this contribution, two boron dipyrromethene (BODIPY)-based donor-acceptor emitters (BDP-C-Cz and BDP-N-Cz) with hybridized local and charge transfer characteristics (HLCT) are introduced in the HF-OLED to suppress the exciton loss by dexter mechanism, and a breakthrough performance with low-efficiency roll-off (0.3%) even at high brightness (1000 cd m(-2)) is achieved. It is demonstrated that the energy loss via the DET channel can be suppressed in HF-OLEDs utilizing the HLCT emitter, as the excitons from the dark triplet state of such emitters are funneled to its emissive singlet state following the hot-exciton mechanism. The developed HF-OLED device has realized a good maximum external quantum efficiency (EQE) of 19.25% at brightness of 1000 cd m(-2) and maximum luminance over 60 000 cd m(-2), with an emission peak at 602 nm and Commission International de L'Eclairage (CIE) coordinates (0.57, 0.41), which is among the best-achieved results in solution-processed HF-OLEDs. This work presents a viable methodology to suppress energy loss and achieve high performance in the HF-OLEDs.