Photovoltaic properties of sintered CdS/CdTe solar cells with TCO electrodes

TCO (transparent conducting oxide) electrodes such as ITO and tin oxide were applied to sintered all-polycrystalline CdS/CdTe solar cells for large-area cell fabrication. Adopting TCO to sintered CdS/CdTe cells caused an increase of leakage current. The leakage current was reduced by using (Cd+Te) mixed slurry instead of CdTe compound slurry to form a CdTe layer because (Cd+Te) mixed slurry can make an improved CdS/CdTe junction during synthesis of CdTe compound. The CdS/CdTe cell with ITO electrode showed slightly larger leakage current and that with SnO₂ electrode showed much larger leakage current, compared to the cell without TCO electrode. However, the reduction of the series resistance of the cell with ITO improved the cell parameters such as J _sc and FF, resulting in maintaining high conversion efficiency of the cells with large area. As a result, the ITO/CdS/CdTe cell with 90 mm² area has an efficiency of 9.4% under irradiation with intensity of 50 mW/cm²