Alain Kassine Ehemba^1,, Mouhamadou Mamour Socé¹, Jean Jude Domingo¹, Salif Cisse¹, Moustapha Dieng¹

The use of the back surface field BSF within the thin film cells isn't elaborated in a current state of research. In this article we try to adapt it to the Cu(In,Ga)Se₂ thin film solar cells. The theoretical study is based on the resolution in one dimension of the equations which govern the behaviour of a photovoltaic cell. The spectrum used is the AM 1.5. The experimental method takes into account all physical phenomena which happen in the solar cell. The comparison of the macroscopic electric parameters of the two cells with BSF and without BSF enabled us to obtain a conversion efficiency of 21.95% for the cell with BSF whereas it is equal to 20.78% for the cell without BSF. The use of the BSF presents a broad maximum absorption band which extends from 0.4µm to 1µm through the study of the quantum efficiency of the cell. The spectral response of the layer reaches a value of 0.7A.W^-1 for an incidental wavelength of approximately 1000nm which corresponds to the gap of the absorber of the solar cell of 1.2eV. The improvement of the thickness of the p+ CIGS up-doped, indicates an optimal thickness of 0.5.µm. We find for this thickness an open circuit voltage of 0.71V, a short-circuit current density of 37.409mA.cm^-2 and a conversion efficiency of 21.95%. The optimization of the doping concentration acceptors of the p+ CIGS, shows that the optimal concentration corresponds to 10E18cm^-3. We find with this acceptors density an open circuit voltage of 0.69V, a short circuit current density of 37.40mA.cm^-2 and a conversion efficiency of 21.74%.

thin film, Back Surface Field, Cu(In, Ga)Se₂, electric parameters