Designing strategies towards non-fullerene DTCR1 based compounds for the exploration of non-linear optical behavior

In this work, non-fullerene based derivatives (DTCD2-DTCD8) with D1-p-D2-p-A architecture were tailored by alteration of terminal acceptor group of a reference molecule (DTCR1) in order to investigate their non-linear optical (NLO) behavior. The effect of peripheral acceptor and donor sites on designed configuration for optical communication and electronic response was examined using DFT based calculations. The natural bond orbitals (NBOs), frontier molecular orbitals (FMOs), UV–Vis analysis, nonlinear optics (NLO), density of states (DOS) and transition density matrix (TDM) were calculated at M06-2X/6-311G(d,p) level. The energy gap of DTCD2- DTCD8 was found to be lowered (DE = 3.970–3.603 eV) with wider absorption spectra as com- pared to that of DTCR1 (4.221 eV). All the derivatives (DTCD2-DTCD8) demonstrated significant NLO behavior than the reference (DTCR1). Among all the designed compounds, DTCD8 exhibited the highest dipole moment (μtotal = 4.777 D), average linear polarizability [α = 1.920 x 10^-22 esu], first hyperpolarizability (βtotal = 10.58 x 10^-28 esu) and second hyperpolarizability (γtotal = 8.028 x 10^-28 esu) as it showed the lowest energy gap (3.603 eV) as compared to the other molecules.