High efficient thin film CdTe solar cells

CdTe thin film solar cell with an absorber layer as thin as 0.5 μm was fabricated. An efficiency of 7.9 % was obtained for a 1-μm-thick CdTe solar cell. The experimental results presented in this study demonstrated that 1-μm-thick absorber layer is thick enough to fabricate CdTe solar cell with a decent efficiency. Formation of mono-grain CdS layer with grain size in submicron was fabricated. Heat treatment of a CdS precursor layer coated with a CdCl₂ layer and under a high CdCl₂ vapor pressure reduced oxide formation at the grain surface and promoted grain coalescence. High crystalline quality mono-grain CdS layer ensured homogenous intermixing of CdS and CdTe at the CdS/CdTe interface. A saturated junction leakage current in the order of 10^-10 A/cm² and a short-circuit current as high as 25.1 cm/cm² were obtained for a mono-grain-CdS/CdTe solar cell. The corresponding solar cell efficiency is 14.6%.