A DFT Study on New Photovoltaic Dyes to Investigate their NLO Tuning at Near Infrared Region (NIR) as Pull-push Effect by End Capped Acceptors.

Abstract

Throughout the opto-electronic devices industry, organic materials with considerable nonlinear optical (NLO) capabilities are being used. By employing 4,6-di(thiophen-2-yl)pyrimidine as a standard molecule, a series for new dyes (DMBMB1-DMBMB6) are created in the present paper by altering their functionalization with various electron acceptor (A) functional groups. The density functional fheory (DFT) and time dependent DFT (TD-DFT) based calculations have been performed to explore NLO responses by adjustment of different A units. The energy gap (Egap) of their highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) was ranged between 0.22-2.43eV which was also used to calculate their global chemical parameters (GRPs). All the new dyes were subjected to UV-Vis studies revealing their frequencies being red shifted from starting dye (DMBMB). The theoretical investigations like frontier molecular orbital (FMO) and natural bond orbital (NBO) analysis was used to investigate their intramolecular chargetransfer (ICT). The dye DMBMB6 had the greatest linear polarizability, first hyperpolarizability (αtotal), and second order hyperpolarizability (βtotal) for all the developed dyes. In conclusion, due of their low ICT, all the dyes showed potential NLO features. Scientific researchers would be able to harness these NLO features to discover NLO materials for current and future uses.