π‐Bridge mediated coupling between inter‐ and intra‐molecular charge transfer in aggregates for highly efficient near‐infrared emission
Jingyi Xu,
Jie Xue,
Yu Dai,
Jinyuan Zhang,
Jiajun Ren,
Chengyu Yao,
Shaman Li,
Qingyu Meng,
Xueliang Wen,
Haoyun Shao,
Juan Qiao
Affiliations
Jingyi Xu
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Jie Xue
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Yu Dai
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Jinyuan Zhang
Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing China
Jiajun Ren
Key Laboratory of Theoretical and Computational Photochemistry College of Chemistry Ministry of Education Beijing Normal University Beijing China
Chengyu Yao
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Shaman Li
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Qingyu Meng
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Xueliang Wen
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Haoyun Shao
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Juan Qiao
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing China
Abstract Intermolecular charge transfer (inter‐CT) is commonly considered to quench luminescence in molecular aggregates, especially for near‐infrared (NIR) emission. Herein, by elaborate comparison of π‐bridge effects in donor/acceptor (D/A) molecules, it is disclosed that a π‐bridge is essential in D/A molecule to involve inter‐CT in aggregates for inducing desired thermally activated delayed fluorescence (TADF) and largely suppressing non‐radiative decays, and importantly, electron‐donating π‐bridge is critical to maximize radiative decay for inter‐CT dominated emission by effective electronic coupling with bright intramolecular charge transfer (intra‐CT) for high‐efficiency NIR emission. As a proof‐of‐concept, TPATAP with thienyl as π‐bridge realized prominent photoluminescence quantum yields of 18.9% at 788 nm in solid films, and achieved record‐high maximum external quantum efficiencies of 4.53% at 785 nm in devices. These findings provide fresh insight into interplay between inter‐CT and intra‐CT in molecular aggregates and open a new avenue to attenuate the limitation of energy gap law for developing highly efficient NIR emitters and improving the luminescent efficiency of various inter‐CT systems, such as organic photovoltaic, organic long persistent luminescence, etc.
