J-Aggregation Enhances the Electroluminescence Performance of a Sky-Blue Thermally Activated Delayed-Fluorescence Emitter in Nondoped Organic Light-Emitting Diodes

Wei Li(South China University of Technology), Wenqi Li(South China University of Technology), Lin Gan(South China University of Technology), Mengke Li(South China University of Technology), Nan Zheng(South China University of Technology), Chengyun Ning(South China University of Technology), Dongcheng Chen(South China University of Technology), Yuan‐Chun Wu, Shi‐Jian Su(South China University of Technology)
ACS Applied Materials & Interfaces
December 18, 2019
10.1021/acsami.9b17585
Cited by 70

Abstract

A pivotal thermally activated delayed-fluorescence (TADF) emitter, DspiroAc-TRZ, was developed, and it exhibits greatly enhanced electroluminescence performance in nondoped organic light-emitting diodes (OLEDs) owing to the concurrent manipulation of aggregation behavior and monomolecular structure. The delicate non-planar packing pattern in the DspiroAc-TRZ crystal can not only lead to highly efficient solid-state luminescence but also form a loose intermolecular packing pattern, greatly decreasing the HOMO or LUMO overlaps in dimers and shortening the triplet exciton diffusion length. In addition, the rigid donor and acceptor moieties in DspiroAc-TRZ can rigidify the molecular backbone, resulting in a tiny geometric vibrational relaxation in the excited state. Impressively, high photoluminescent quantum yields of 78.5 and 83.7% were achieved for the DspiroAc-TRZ single crystal and nondoped film. A high external quantum efficiency (EQE) of 25.7% was achieved in a nondoped sky-blue TADF OLED, which is higher than any reported EQE value of nondoped sky-blue TADF OLEDs so far.

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