Exploration the effect of selenophene moiety and benzothiophene based acceptors on optical nonlinearity of D-π-A based heterocyclic organic compounds in chloroform solvent: A DFT approach

Currently, fullerene-free organic chromophores find widespread use in the endeavor to enhance the efficacy of NLO materials. Considering the significance of NF organic systems, we fabricated a push-pull series of heterocyclic organic compounds (DTPD1-DTPD8) from DTPR by molecular engineering with benzothiophene acceptors at one terminal. Owing to the larger size, greater charge transference and higher polarizability nature of selenophene than that of thiophene, the pi-spacer was replaced with selenophene. The effect of selenophene moiety and benzothiophene based acceptors on optical nonlinearity of DTPD1-DTPD8 was explored through quantum chemical study. DFT approach at M06/6-311G(d,p) functional was employed in order to explore the optoelectronic properties of designed chromophores. The FMOs findings disclosed a substantial reduction in band gaps (2.107-3.057 eV) in derivatives than that of DTPR (3.12 eV). An effective charge transference from donor to acceptor via spacer was observed in HOMO/LUMO which further supported by DOS and TDM heat maps. GRPs findings revealed that all derivatives had higher softness (sigma = 0.327-0.475 eV(-1)) with lower hardness (eta = 1.04-1.53 eV) than that of DTPR which expressed the higher polarization in derivatives. Significant advancements in nonlinear optical (NLO) outcomes were obtained for all the derivatives as compared to reference chromophore. Particularly, DTPD6 exhibited the efficient response [ <alpha> = 1.561x10(-22), beta(total) = 2.111x10(-27) esu] among all tailored chromophores owing to its unique characteristics such as reduced band gap (2.107 eV) highest softness value (0.475 eV) with lowest hardness value at 1.04 eV. This structural modification by utilizing selenophene pi-spacer and benzothiophene acceptor played a protruding role in attaining promising NLO responses. Thus, this study tempted the experimentalists to synthesize the proposed NLO materials for the modern optoelectronic high-tech applications.