eng Science and Education Publishing American Journal of Energy Research 2328-7330 2018-07-19 6 1 23 29 10.12691/ajer-6-1-4 AJER2018614 article Ousmane Diagne usman.diagn@gmail.com 1 Djimba Niane 1 Alain Kassine Ehemba 1 Mouhamadou Mamour Soce 1 Moustapha Dieng 1 Laboratory of Semiconductors and Solar Energy, Physics Department, Sciences and Technologies Faculty, Cheikh Anta Diop University, Dakar, Sénégal We carried out, through the SCAPS-1D simulator, the survey of the curves of spectral response and J/V characteristic for different parabolic bandgap profile CIGS solar cells. The variable parameter for these different samples is the gallium rate of the CIGS absorber layer. The theoretical model coincides with the one-dimensional model of a heterojunction consisting of a window layer (ZnS), a buffer layer (CdS) and an absorbing layer (Cu(In,Ga)Se?). The analysis of the results obtained allowed us to identify and evaluate the adjustments that would have to be made, compared to the gallium composition, in order to have an optimal efficiency. Thus, after various adjustments, we obtain a powerful cell that displays a conversion efficiency of around 23.68%. This cell is characterized by a bowing factor (b) equal to 10% and Ga local composition rates equal to 25% and 35% respectively at the junction and the back contact. http://pubs.sciepub.com/ajer/6/1/4/ajer-6-1-4.pdf CIGS solar cells grading bandgap [Ga/(In+Ga)] ratio electrical parameters SCAPS-1D