When periodically packing the intramolecular donor-acceptor structures to form ferroelectric-like lattice identified by second harmonic generation, our CD49 molecular crystal shows long-wavelength persistent photoluminescence peaked at 542 nm with the lifetime of 0.43 s, in addition to the short-wavelength prompt photoluminescence peaked at 363 nm with the lifetime of 0.45 ns. Interestingly, the long-wavelength persistent photoluminescence demonstrates magnetic field effects, showing as crystalline intermolecular charge-transfer excitons with singlet spin characteristics formed within ferroelectric-like lattice based on internal minority/majority carrier-balancing mechanism activated by isomer doping effects towards increasing electron-hole pairing probability. Our photoinduced Raman spectroscopy reveals the unusual slow relaxation of photoexcited lattice vibrations, indicating slow phonon effects occurring in ferroelectric-like lattice. Here, we show that crystalline intermolecular charge-transfer excitons are interacted with ferroelectric-like lattice, leading to exciton-lattice coupling within periodically packed intramolecular donor-acceptor structures to evolve ultralong-lived crystalline light-emitting states through slow phonon effects in ferroelectric light-emitting organic crystal.
Bibliographical noteFunding Information:
This research was supported by Air Force Office of Scientific Research (AFOSR) under the grant number AOARD (FA2386-17-1-4060; FA2386-15-1-4104), and National Science Foundation (NSF-1911659). This research was partially conducted at the Center for Nanophase Materials Sciences based on user projects (CNMS2019-245), which is sponsored by Oak Ridge National Laboratory by the Division of Scientific User Facilities, U.S. Department of Energy. The author (Y.D.) acknowledges the financial support from the China Scholarship Council through university agreement for her Ph.D. study at the University of Tennessee. The UTK authors thank the Center for Materials Processing, a Center of Excellence at the University of Tennessee at Knoxville, funded by the Tennessee Higher Education Commission, for financial support (M.W.). We also thank Professor Frank Loeffler, Dr. Gao Chen, and Yanchen Sun for the help on the HPLC test at the University of Tennessee at Knoxville.
© 2021, The Author(s).
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)