Theoretical Study on Optoelectronic Properties of 1,4-Dithiazole-5,10-dihydrophenazine and Its B ← N-Fused Derivatives.

Recently, Liu et al. reported 1,4-dithiazole-5,10-dihydrophenazine () and its B ← N-fused derivative (), which were expected to show excellent optoelectronic properties ( , 61, e202205893). However, their charge-transport performance and luminescence emission mechanisms have not been revealed. In this work, we used density functional theory (DFT) calculations to investigate the optoelectronic properties of and and analyzed the influence of the introduction of -BF on the basic parameters governing charge transport and injection in detail. Our calculation results showed that adding -BF could stabilize the frontier molecular orbitals and decrease the reorganization energies associated with electron transport due to the formation of B ← N bonds, and the intermolecular electronic couplings are greatly enhanced owing to the strong intermolecular F···H interactions. Based on the master equation coupled with the Marcus-Hush electron transfer theory, we theoretically predicted the charge transport properties of and . The optimum hole mobility (3.87 cm V S) and electron mobility (1.52 cm V S) of are, respectively, 3 and 9 times as high as the corresponding optimum values of compound . Moreover, the assignments of multiple fluorescence bands in the experiment were confirmed by time-dependent density functional theory (TDDFT) calculations. The simulated emission spectra indicate that the experimental fluorescence maxima at 687 nm originates from the S → S transition of the double proton transfer phototautomer () of and the shoulder peak at ∼660 nm may be related to the excited-state single-proton transfer phototautomer (); for , the experimental fluorescence maxima at 687 nm should be attributed to normal Stokes shifted emission, and the shifted fluorescence with a peak at 751 nm originates from the emission of the photodissociation product of .