In this study, we propose a simple structure of an organic heterojunction solar cell of OTC/ED/EA type. Material energy values are used for the first time. The study concerns a numerical simulation using SCAPS. Under standard conditions: AM1.5 and T = 300K, the cell parameters are: Voc = 1.186V, Jsc = 14.314mA/cm2, FF = 88.57% and Eff = 15.04%. The effects of parameters such as thickness, energy band gap, ND and NA charge carrier density of state, of the active layers were observed. It appears that, apart from the ND density of state, all the other material parameters influence the values of the cell parameters. It is still necessary to limit the value of NA to avoid degenerated cells. The influence of temperature has also been studied. It was found that when the temperature increases, the performance of the cell decreases. This work is essential because it provides the scientific community with data to make organic solar cells more efficient.