Intramolecular Sensitization Assisting High-Efficiency TADF Conjugated Polymers with Accelerating Exciton Spin Flip for Solution-Processed Electroluminescent Devices

Abstract

Thermally activated delayed fluorescence (TADF) conjugated polymers have attracted a lot of attention for their potential to produce flexible display devices. However, insufficient energy transfer from the host to TADF units will result in exciton− exciton annihilation and reduced device efficiency. To address these problems, an intramolecular sensitization strategy is employed in this work in which the spin flip of a triplet exciton can be accelerated by the intermediation of TADF sensitization units in polymers. By regulating the ratio of each polymeric component, excellent photophysical properties can be achieved with a photoluminescence quantum yield of 86% and a high rate of reverse intersystem crossing of 6.3 × 10 5 s −1 . Moreover, the solution-processed polymer-based organic light-emitting diodes can achieve an attractive external quantum efficiency of 21.02% due to the effective utilization of triplet excitons. Overall, this research validates the feasibility of an intramolecular sensitization strategy for restraining exciton annihilation, thus providing a promising pathway for designing high-performance conjugated TADF polymers.