Electronic, non-linear optical, optoelectronic, and thermodynamic properties of undoped and doped bis (ethylenedithio) tetraselenafulvalene (BETS) (CHSSe) molecule: first study using ab initio investigation.

We have performed the ab initio calculation of the undoped and doped molecules bis (ethylenedithio) tetraselenafulvalene (BETS). Carbone (C) atoms have been substituted by Boron (B) to investigate their effects on the electronic structure and nonlinear optical, optoelectronic, and thermodynamic properties of BETS molecule. The RHF and hybrid density functional theories (WB97XD, B3PW91, and B3LYP) methods were applied, using the cc-pVDZ basis set. We found that the energy gap (Egap) of the doped molecules are respectively 2.476 eV and 2.569 eV for CBHSSe and CBHSSe with B3LYP/cc-pVDZ basis set, lower than one of the undoped molecule (3.316 eV). The significant increase values of polarizability (˂α˃) and first order hyperpolarizability (β) of the doped compounds, especially in CBHSSe (< α >  = 4.5315 × 10 esu, β = 22,672.27 × 10 esu and < α >  = 4.518 × 10 esu, β = 23,657.43 × 10 esu respectively for B3LYP and B3PW91) compared to those of the undoped molecule (< α >  = 4.3602 × 10 esu, β = 1290.38 × 10 esu, and < α >  = 4.518 × 10 esu) show that the new molecules have a good nonlinear optical property. Results suggest that these molecules doped with boron are a potential candidate as semiconductors compounds and nonlinear optical materials.