A carbazole-substituted tris(trichlorophenyl)methyl radical belongs to a new class of luminescent material that have been used in many photonic applications including Organic Light Emitting Devices (OLEDs) and light-harvesting/modulation systems. Previous studies have shown that the efficiency (QY) of the radiative relaxation from the doublet excited state(s) of this free radical chromophore is affected by the polarity of the medium. Specifically, these studies suggest that the radiative process is enhanced in non-polar solvents but seemingly quenched in polar media. In our ongoing effort to depict the photophysical “passport” of this open-shell chromophores (and its derivatives), we used steady-state and time-resolved spectroscopy tools to investigate the effect of solvent polarity on the dynamic and/or kinetic of excited state species. While it was found that the population of excited state would involve two conformational photo-isomers, we were able to ascertain that the (statistical) distribution of the two excited state species depends on the orientation polarizability of the medium. Preliminary evidence indicates that the relaxation of the most polar photo-isomer is dominated by a quasi-non-radiative decay.<br/>My presentation will highlight the ground- and excited-state nature of the open-shell chromophores of our interest. Moreover, I will describe the relationship between the photo-behavior of these chromophores and the polarizability of the medium.

Unraveling the photo-excited state characteristic/nature of a triarylmethyl-based open-shell chromophore

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ACS Fall 2022

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