Dendritic Oligomers-Based Exciplex Emitters Realizing Solution-Processed Organic Light-Emitting Diodes with Nearly 30% External Quantum Efficiency

Due to the feature of the strong intermolecular interactions causing aggregation-caused excitons quenching (ACQ) of solution process, realizing high-performance solution-processed organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters remains a formidable challenge nowadays. To address this issue, herein, a novel strategy is proposed to construct solution-processable ternary exciplex emitters by utilizing the dendritic oligomer as the substrate, simultaneously realizing excellent solution-process adaptability, good dispersibility to restrain harmful ACQ, and improved exciton utilization with multiple reverse intersystem crossing channels. Accordingly, dendritic oligomer-based exciplex systems are constructed by combining small-molecule donor and acceptor components with the multi-carbazole-substituted tetraphenylsilane-core analog as substrate. And their film morphologies, photoluminescence quantum yields (Phi PLs), and non-radiative decay rates of triplet excitons (knrTs) are significantly improved. Among them, DMAC-DPS:PO-T2T:SimCP3 exhibits the highest Phi PL of 97.5% and the lowest knrT of 1.0 x 103 s-1, and realizes the best maximum external quantum efficiency of 29.7% in solution-processed OLED, which is comparable with the highest electroluminescence efficiencies of all solution-processable emitters. Therefore, this work will provide a prospective pathway to develop efficient solution-processable exciplex emitters and promote the progress of solution-processed OLEDs. A novel strategy to construct solution-processable exciplex emitters is proposed by utilizing the dendritic oligomer as substrate, simultaneously realizing excellent solution-process adaptability, good dispersibility to restrain intermolecular aggregation-caused quenching, and improved exciton utilization. Impressively, DMAC-DPS:PO-T2T:SimCP3 achieves an external quantum efficiency of 29.7% in solution-processed device, which is comparable with the best results among all solution-processable emitters. image