2025-07-30 九州大学
＜関連情報＞
- https://www.kyushu-u.ac.jp/ja/researches/view/1303
- https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202509857
トリアジン系発光体における二重機能の解明： 電子吸引性置換基による二光子吸収とTADF-OLED性能の相乗的向上 Unlocking Dual Functionality in Triazine-Based Emitters: Synergistic Enhancement of Two-Photon Absorption and TADF-OLED Performance with Electron-Withdrawing Substituents
Youhei Chitose, Gomathi Vinayakam Mageswari, Ryota Zenke, Toshiharu Ide, Shintaro Kohata, Ja-Hon Lin, Tzu-Chau Lin, Youichi Tsuchiya, Chihaya Adachi
Advanced Materials Published: 29 July 2025
DOI:https://doi.org/10.1002/adma.202509857
Abstract
The simultaneous realization of two-photon absorption (2PA) and thermally activated delayed fluorescence (TADF) in a single molecular system remains challenging due to an inherent trade-off in their molecular design requirements. In this study, we present a strategy to enhance both properties by introducing electron-withdrawing substituents into the CzTRZ scaffold, thereby leveraging an electron-withdrawing-enhanced intramolecular charge transfer (EWICT) character. The incorporation of TRZCF3 and TRZCN units effectively enhances the charge transfer (CT) character of CzTRZ, resulting in high 2PA cross-sections (156 GM for CzTRZCF3 and 200 GM for CzTRZCN) and a reduced singlet-triplet energy gap (ΔEST = ES1 – ET1). Computational and experimental studies reveal that incorporating TRZCF3 and TRZCN units selectively stabilizes the S1 state and reduces ΔEST, significantly facilitating the reversed intersystem crossing (RISC) process. Notably, 1c exhibits the fastest RISC rate (kRISC), leading to superior TADF properties and an external quantum efficiency (EQE) of 13.5% in OLEDs. Moreover, a relatively high two-photon brightness of 174 GM is estimated for 1c. These findings demonstrate a rational molecular design strategy for the synergistic enhancement of 2PA cross-sections and excellent OLED performance, paving the way for applications in advanced imaging probes and organic semiconductors.
