Due to their environment-friendly, simple assembly technology, physical flexibility and low cost, organic solar cells sush as bulk heterojunction (BHJ) and Dye sensitized solar cells (DSSCs) cells have been the subject of intensive academic interest over the past two decades. The active layer of these cells use organic conjugated compounds; a donor (D) and an acceptor (A) between two different electrodes. The power conversion efficiency of these devices has achieved 10% for BHJ and almost 12% for DSSC. In order to enhance this efficiency, a theoretical study based on DFT and TD-DFT is the best approach to calculate and to predict the electronic structure and the spectroscopy properties of these materials. In this work, we calculated and investigated the optoelectronic (HOMO, LUMO, Egap, Wave length of absorption / emission,¿) and photovoltaic (Open circuit voltage Voc, Power conversion efficiency ¿, ¿ ) properties of a series of severels conjugated compounds for BHJ and DSSC cells applications.