Approaching high efficiencies over 13% with 2-/spl mu/m thick CdS/CdTe thin film solar cells

Highly efficient CdS/CdTe thin film solar cells with thinner PV active layers are required from a view point of reduction of production cost as well as toxicity of Cd. We have achieved the conversion efficiency of 13.5% (V/sub oc/: 0.799 V, J/sub sc/: 24.8 mA/cm/sup 2/, F.F.: 0.679, area: 0.42 cm/sup 2/) using 2.0-/spl mu/m thick PV active layers. High efficiencies were obtained with annealing temperatures at CdCl/sub 2/ treatment lower than those for conventional thick (5-10 /spl mu/m) solar cells. Furthermore, higher oxygen concentration of 7% at the CdCl/sub 2/ treatment was found to be effective for improvement of the efficiencies.