TADF polymer enables over 20% EQE in solution‐processed green fluorescent OLEDs
Libing Yan,
Ning Su,
Ying Yang,
Xue Li,
Jie Sun,
Shumeng Wang,
Lei Zhao,
Liming Ding,
Junqiao Ding
Affiliations
Libing Yan
School of Chemical Science and Technology Yunnan University Kunming China
Ning Su
School of Chemical Science and Technology Yunnan University Kunming China
Ying Yang
School of Chemical Science and Technology Yunnan University Kunming China
Xue Li
School of Chemical Science and Technology Yunnan University Kunming China
Jie Sun
Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS), Center for Excellence in Nanoscience (CAS), Center for Excellence in Nanoscience (CAS) National Center for Nanoscience and Technology Beijing China
Shumeng Wang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China
Lei Zhao
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China
Liming Ding
Key Laboratory of Nanosystem and Hierarchical Fabrication (CAS), Center for Excellence in Nanoscience (CAS), Center for Excellence in Nanoscience (CAS) National Center for Nanoscience and Technology Beijing China
Junqiao Ding
School of Chemical Science and Technology Yunnan University Kunming China
Abstract Solution‐processed fluorescent organic light‐emitting diodes (OLEDs) are believed to be favorable for low‐cost, large‐area, and flexible displays but still suffer from the limited external quantum efficiency (EQE) below 5%. Herein, we demonstrate the EQE breakthrough by introducing a donor–acceptor type thermally activated delayed fluorescence (TADF) polymer as the sensitizer for the typical green‐emitting fluorescent dopants. Benefitting from their matched energy alignment, the unwanted trap‐assisted recombination directly on fluorescent dopant is prevented to avoid the additional loss of triplet excitons. Indeed, triplet excitons are mainly formed on the polymeric TADF sensitizer via a Langevin recombination and then spin‐flipped to singlet excitons due to the good upconversion capability. Followed by an efficient Förster energy transfer, both singlet and triplet excitons can be harvested by fluorescent dopants, leading to a promising solution‐processed green hyperfluorescence with a record‐high EQE of 21.2% (72.2 cd/A, 59.7 lm/W) and Commission Internationale de L'Eclairage coordinates of (0.32, 0.59). The results clearly highlight the great potential of solution‐processed fluorescent OLEDs based on TADF polymers as the sensitizer.
