Enhancing the Performance of Green Quantum Dot Light-Emitting Diodes Through an Efficient Förster Resonance Energy Transfer Based Exciton Recycling Strategy.

Aiming at the issue of unbalanced carrier injection in conventional quantum dot light-emitting diodes (QLEDs), this study adopts a solution based on Förster Resonance Energy Transfer (FRET). However, the limited fluorescence lifetime of existing FRET donor materials restricts the efficiency of this strategy in green QLEDs. To address this problem, this study employs the thermally activated delayed fluorescence (TADF) material bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]methanone (DMAC-BP) with a long emission lifetime as an exciton sensitization layer, which is embedded as a thin film between the hole transport layer and the quantum dot emission layer. This structural design significantly enhances the FRET efficiency to 77.29%, thus efficiently transferring excitons to the quantum dot emission layer. On this basis, the fabricated green QLEDs achieve a maximum external quantum efficiency (EQE) of 20.21% and a maximum current efficiency (CE) of 90.59 cd/A, representing improvements of approximately 38% compared to reference devices without a sensitizing layer. Meanwhile, the device lifetime (T80) was extended to 5 times that of the standard device. This work not only verifies the advantages of TADF materials in addressing the FRET efficiency problem of green QLEDs, but also pioneers a new practical pathway for the development of high-performance and long-lifetime QLEDs.