Enhancing the Operational Lifetime of OLEDs Through the Modulation of Rigidity and Excited‐State Properties
Abstract
Abstract Blue‐emitting multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters with high photoluminescence quantum yield (PLQY), high robustness with short‐lived emission lifetime is particularly desired for the development of organic light‐emitting diodes (OLEDs). In this study, a series of MR‐TADF molecules featuring fused boron/nitrogen (B/N) and C ═ O/N frameworks is reported. These emitters namely BNO , BNDO , and BNTO are systematically designed and synthesized to investigate the impact of molecular rigidity or planarity toward their excited‐state dynamics through stepwise intramolecular electrophilic acylation reactions. Computational studies and single‐crystal X‐ray diffraction data revealed the enhanced planarity of BNDO and BNTO . Upon photoexcitation, these compounds exhibited blue emission with PLQYs of approaching unity and short‐lived delayed lifetimes (<2 µs). BNTO ‐based OLEDs achieved sky‐blue emission peaking at 489 nm, a moderate device operational lifetime of over 500 h at 70% of the initial brightness (LT 70 ) at 1000 cd m −2 , which shows longer device stability when compared with BNO and greener emission when compared to BNDO . This study highlights that manipulation of the rigidity of compounds and emissive states of MR‐TADF compounds is essential in achieving blue emission and improving OLED operational stability.
Article Details
Authors (9)
Yu Mei Hu
Institute of Materials Research Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 China
Maggie Ng
Xiongkai Tang
New Cornerstone Science Laboratory, State Key Laboratory for Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and National & Local Joint Engineering Research Center of Preparation Technology of Nanomaterials, College of Chemistry and Chemical Engineering
Cangyu Wang
Institute of Materials Research Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 China
Yuqi Huang
Xianglian Zhu
The Education Ministry Key Lab of Resource Chemistry Shanghai Key Laboratory of Rare Earth Functional Materials Shanghai Frontiers Science Center of Biomimetic Catalysis College of Chemistry and Materials Science Shanghai Normal University Shanghai 200234 China
Panpan Li
Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, State Key Laboratory of Synergistic Chem-Bio Synthesis, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
Season Si Chen
Institute of Environment and Ecology Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen P.R. China
Man‐Chung Tang
Institute of Materials Research Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen P.R. China