Hui Jun-Yang, Zhou Hai-Ping, Sun Ying, Li You-Liang, Pan Qing-Qing, Kan Yu-He, Su Zhong-Min
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Jilin Provincial International Joint Research Center of Photo-functional Materials and Chemistry, Changchun 130022, China.
State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Mar 15;329:125592. doi: 10.1016/j.saa.2024.125592. Epub 2024 Dec 16.
Neutral radicals have the potential to construct pure organic light-emitting diodes (OLEDs) with internal quantum efficiencies reaching 100%. However, neutral radical luminescent materials with emission wavelengths in the second near-infrared (NIR-II) window are rare. Herein, a serial of neutral donor-bridge-acceptor (D-π-A) type radical derivatives are investigated. The dominant elements influencing the luminescent properties of neutral radicals, such as chemical stability, excited state characteristics, radiative decay rate (k) and internal conversion rate (k) constants are taken into consideration. Theoretical calculations reveal that introducing heteroatomic fused-rings into neutral radicals can modulate the chemical stability and result in a red shift of the emission wavelength spectrum. In the presence of charge transfer characteristics, by increasing the effective overlap between the hole and electron wavefunctions, the k constants of the neutral D-π-A type radicals increase. In addition, avoiding the geometric relaxation between the lowest excited state (D) and the ground state (D), as well as reducing electron-vibration coupling and non-adiabatic coupling in the low-frequency region can effectively decrease the k constants. Our study proposes an innovative design approach aiming to develop stable and efficient NIR-II window neutral radical luminescent materials utilizing heteroatomic fused-rings as key elements.
中性自由基有潜力构建内部量子效率达到100%的纯有机发光二极管（OLED）。然而，发射波长在第二近红外（NIR-II）窗口的中性自由基发光材料却很罕见。在此，研究了一系列中性供体-桥-受体（D-π-A）型自由基衍生物。考虑了影响中性自由基发光特性的主要因素，如化学稳定性、激发态特性、辐射衰减率（k）和内部转换率（k）常数。理论计算表明，将杂原子稠环引入中性自由基可调节化学稳定性并导致发射波长光谱红移。在存在电荷转移特性的情况下，通过增加空穴和电子波函数之间的有效重叠，中性D-π-A型自由基的k常数增加。此外，避免最低激发态（D）和基态（D）之间的几何弛豫，以及减少低频区域的电子-振动耦合和非绝热耦合，可以有效降低k常数。我们的研究提出了一种创新的设计方法，旨在开发以杂原子稠环为关键元素的稳定高效的NIR-II窗口中性自由基发光材料。
