Abstract :

In this article, we study the influence of interface and surface recombination effects on the performance of a solar cell and on the photocurrent profile. This study is applied to chalcopyrite thin film solar cell comprising 4 active layers following the model ZnO(n+)/CdS(n)/CuInS2(p)/CuInSe2(p+) where CuInS2 represents the base and CuInSe2 the substrate. It is based on the continuity equation of charge carriers in semiconductor material and the consideration of certain optical, geometric and electrical parameters (photon absorption coefficient, diffusion length, recombination velocity at the front and the back surface and at the interface between different layers, thicknesses of the layers, etc.). We also consider monochromatic illuminations ranging from visible to near infrared. The results obtained in two-dimensional and three-dimensional representations, show that surface and interface recombination centers can dramatically reduce the efficiency of the collection of carriers for certain wavelength ranges and that the efficiency depends on the area of photon absorption. The photons generated in the depletion area or close to this area are less affected by surface defects. The losses are related to the charge carriers which cross the interfaces to reach the depletion region and those which are generated in the vicinity of the surface because of the diffusion of the latter are towards the recombination centers.