Solution-processed white OLEDs with power efficiency over 90 lm W-1 by triplet exciton management with a high triplet energy level interfacial exciplex host and a high reverse intersystem crossing rate blue TADF emitter

Liang Chen; Yufei Chang; Song Shi; Shumeng Wang; Lixiang Wang

doi:10.1039/d1mh02060a

Solution-processed white OLEDs with power efficiency over 90 lm W^-1 by triplet exciton management with a high triplet energy level interfacial exciplex host and a high reverse intersystem crossing rate blue TADF emitter

Mater Horiz. 2022 Apr 4;9(4):1299-1308. doi: 10.1039/d1mh02060a.

Authors

Liang Chen^{1

2}, Yufei Chang^{1

2}, Song Shi^{1

2}, Shumeng Wang¹, Lixiang Wang^{1

2}

Affiliations

¹ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. wangshumeng@ciac.ac.cn.
² School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China.

PMID: 35195631
DOI: 10.1039/d1mh02060a

Abstract

Solution-processed white organic light-emitting diodes (WOLEDs) have shown much lower device efficiency than their vacuum-deposited counterparts, due to the lack of triplet exciton management in a single-emissive-layer device structure, which will induce triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA). Here, two kinds of solution-processed WOLEDs, including thermally activated delayed fluorescence (TADF)/phosphorescence hybrid WOLEDs and all-TADF WOLEDs, with high power efficiency are developed by using a high triplet energy level (T₁) interfacial exciplex as a host and a high reverse intersystem crossing (RISC) rate TADF emitter as a blue dopant for triplet exciton management. The interfacial exciplex host with high T₁ can ensure that triplet excitons transfer from the host to the blue emitter, and the blue TADF emitter with high RISC rate (1.15 × 10⁷ s^-1) can rapidly upconvert triplet excitons to singlet ones to avoid TTA and TPA. The solution-processed TADF/phosphorescence hybrid and all-TADF WOLEDs exhibit maximum external quantum efficiencies of 31.1% and 27.3%, together with maximum power efficiencies of 93.5 and 70.4 lm W^-1, respectively, which are the record efficiencies for solution-processed WOLEDs, and quite comparable to those of most vacuum-deposited counterparts.