Deepening Insights into Near-Infrared Excited-State Intramolecular Proton Transfer Lasing: The Charm of Resonance-Assisted Hydrogen Bonds
Wan-Ying Yang1, Run-Chen Lai2, Jun-Jie Wu1, You-Jun Yu1, Chang-Cun Yan1,*, Chao-Fan Sun3,*, Xue-Dong Wang1,*, Liang-Sheng Liao1,4
1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren'ai Road, Suzhou, Jiangsu 215123, P. R. China
2State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang 310013, P. R. China
3College of Science, Northeast Forestry University, Harbin 150040, Heilongjiang, P. R. China
4Macao Institute of Materials Science and Engineering, Macau University of Science and Technology, Taipa 999078, Macau SAR, P. R. China
Excited-state intramolecular proton transfer (ESIPT)-active organic semiconductor materials, characterized by a or several resonance assisted hydrogen bonds (RAHBs), are supposed to be ideal candidates for achieving high-performance near-infrared (NIR) lasers. However, according to the energy gap law, the development of ESIPT-active gain materials is still limited by the serious nonradiative decays. Herein, it is demonstrated that RAHBs can activate ESIPT lasing by inhibiting nonradiative decays. A new ESIPT-active material 1,5-dihydroxy2,6-diphenylanthraquinone (DP-DHAQ) containing two centrosymmetric RAHBs is developed, which exhibits a ≈100-fold higher radiative decay rate (kr = 1.1 × 1010 s-1) in doped polystyrene (PS) film than that of 1-hydroxy5-methoxy-2,6-diphenylanthraquinone (DP-HMAQ) and 1,5-dimethoxy2,6-diphenylanthraquinone (DP-DMAQ), in which one and two RAHBs are broken, respectively, by introducing methyl groups. Both DP-DHAQ and DP-HMAQ can form four-level systems based on the ESIPT processes, but only DP-DHAQ doped PS microspheres exhibit laser emission at 710 nm under the test conditions. It is worth mentioning that single-crystal microplates of DP-DHAQ can realize NIR laser emission at 725 nm. The results suggest that RAHBs can effectively activate the gain property of ESIPT-active materials, which deepens insights into NIR ESIPT lasing and provides a new proposal for the design of organic laser-active molecules.