Dipole-Dipole Interaction Management for Efficient Blue Thermally Activated Delayed Fluorescence Diodes

作者：Han, Chunmiao; Zhang, Zhen; Ding, Dongxue; Xu, Hui^*

来源：Chem, 2018, 4(9): 2154-2167.

DOI：10.1016/j.chempr.2018.06.005

• EXTERNAL QUANTUM EFFICIENCY
• LIGHT-EMITTING-DIODES
• PHOSPHINE-OXIDE HOST
• HIGH TRIPLET ENERGY
• BIPOLAR HOST
• HIGH-PERFORMANCE
• ELECTRICAL-PROPERTIES
• UNIVERSAL HOST
• PHOSPHORESCENT
• DEVICES

Thermally activated delayed fluorescence (TADF) diodes have emerged in recent years. However, blue devices still suffer from low luminance and serious efficiency roll-off, partially because of the utilization of unipolar host materials, which can suppress interaction-induced quenching at the cost of carrier flux unbalance. Herein, we demonstrate that the strong host excited-state dipole field can significantly worsen exciton quenching of blue TADF dopants through hostdopant dipole-dipole interactions. To integrate low excited-state polarity and ambipolar characteristics, we developed a donor-s-acceptor host with dramatically reduced excited-state dipole moments by one order of magnitude to only similar to 2 Debye, which gave rise to state-of-the-art external quantum efficiency beyond 20% from its devices, as well as record-low roll-off. Comparison between the device efficiencies of the hosts and various excited-state polarities revealed that the suppression of dipole-dipole interaction-induced quenching is the primary determinant of device performance for ambipolar blue TADF hosts.

• 出版日期2018-9-13
• 单位黑龙江大学