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.