Photoluminescence Mechanism of Dual-State Emission Materials Based on the Sulfone Bridged Distyrylbenzene Derivative

Herein, a novel molecular SO2-Bri-DSB based on the sulfone-bridged distyrylbenzene derivative is synthesized, and its organic crystal is fabricated. It has a very high photoluminescence (PL) quantum efficiency in the solution and crystalline state, i.e., dual-state emission (DSE), and the corresponding PL mechanism is clarified in detail using the transient absorption and transient PL test. The PL behaviors in the monomolecular state and organic crystal are compared. In addition, the optical anisotropy of the SO2-Bri-DSB crystal is thoroughly investigated using various polarization-dependent spectroscopy techniques. The time evolution of anisotropy is composed of a step behavior caused by the anisotropy of the electronic transition and a slow enhancing process with a lifetime of 4.86 ns, which is governed by the change in emission lifetime due to the anisotropy. The space-resolved evolution of the optical anisotropy is investigated using the polarization-dependent light wave-guiding test and exhibits that the emission anisotropy gradually decreases with length, and it has a longer effective propagation length than the polarization emission signal. The findings provide insight into the intrinsic optical anisotropy of single-molecular crystals and indicate that these materials have enormous potential in the domains of polarization lighting and display. A new dual-state emission (DSE) molecule SO2-Bri-DSB is synthesized, and its luminescence mechanism in the monomolecular system and molecular crystals is also compared in detail. Furthermore, the evolution of optical anisotropy of SO2-Bri-DSB crystals with time and space is revealed by using a variety of polarization correlation spectroscopy techniques.image