الخلاصة

Abstract. In the current search, we have reported the theoretical analysis by utilizing DFT (TDDFT)- B3LYP at 6-31G (d, p) level on the geometries, optoelectronic and absorption characteristics of novel series of the donor-π-acceptor dyes. The π-conjugated bridge is based on the thiophene, benzene, pyridine, and pyrazine; the thieno [2,3-b] indole has been used as an electron donor (D) and theeacida2-cyanoacrylic has been used as an electron acceptor (A) group. The theoretical information of the electronic structures, such as energy levels (HOMO and LUMO) and energy gap of the molecules, is based on studying the dyes in organic solar cells. Consequently, the energy levels, energy gap, photovoltaic properties, quantum chemical and absorption parameters of all the dyes have been computed and reported. The calculations show that the dyes under study can theoretically be good photosensitizers in DSSCs. Moreover, the results indicate that the LUMO levels of all dyes design lie over the conduction band (Ecb) of the semiconductors TiO2 (or PC70BM) likewise the HOMO levels lie under the decrease potential vitality of the I−/I3 − (electrolytes) in comparison to the ability of electron transfer from the molecular dye excited state to TiO2 (or PC70BM) and chargeerenewal after photo-oxidation process, separately.