EFFICIENCY IMPROVEMENT OF CDTE SOLAR CELLS WITH ULTRA-THIN CDS LAYER

CdTe solar cells have performed excellent efficiencies up to 22,1%. In order to reach these remarkable values it is very important to reduce or completely remove the parasitic absorbance of the CdS buffer layer. One path is to reduce the thickness and by doing so to allow the light transmittance in the low wavelength region. In this scope, ultra-thin CdS has been grown in order to enhance the photocurrent generated in CdS/CdTe thin film solar cells. However reducing CdS thickness is generally detrimental for the solar cell performance with a standard transparent conductive oxide, due to the formation of shunts for a non homogeneous coating of the buffer layer particularly after CdCl2 treatment that enhances sulphur interdiffusion into the CdTe.. In this paper we present a study of different treatments of the CdS buffer layer, which are introduced in order to stabilize the material and limit the consumption of CdS under the CdTe activation treatment. A study of the effect of different treatments on CdS with goal to improve the layer’s structural stability and electrical performance is presented.