In this paper, a theoretical study of several conjugated aromatic compounds based on several pyrroleis reported using Density Functional Theory method (DFT). Theoretical calculation has been carried out in order to characterize their stability, geometric and electronic properties. In fact, substituent nature, number and position are crucial parameters to define structural and electronic molecule properties. Besides, assessing HOMO and LUMO energy levels of compounds is essential in investigating suitable materials for optoelectronic applications. The theoretical knowledge of HOMO and LUMO energy levels of the components are basic in studying organic solar cells, so the HOMO, LUMO and Gap energy Voc (open circuit voltage) of the studied compounds have been calculated and discussed. The properties suggest these materials as a good candidate for organic solar cells.
