Abstract
In this paper and in order to guide the synthesis of novels materials with low band gaps, Theoretical study by using DFT method on six conjugated compound containing based on thiadiazolothienopyazine is reported. Different electron side groups were introduced to investigate their effects on the electronic structure. The theoretical knowledge of the HOMO and LUMO energy levels of the components is basic in studying organic solar cells so the HOMO, LUMO and Gap energy of the studied compounds have been calculated and reported. These properties suggest these materials as a good candidate for organic solar cells.