The CdS/CdTe solar cell protected by ITO/Mo bilayer at improved back contact

In this work CdS/CdTe solar cell that uses a Mo thin film as a back contact on last layer was protected against MoO_x formation and scratching by using an ITO thin film. The back contact was fabricated by using Cu/Mo and Cu/Mo/ITO. The Cu layer was used to form Cu_xTe onto CdTe film. The films Cu, Mo and ITO were deposited by rf-sputtering. The cell efficiency is degraded when it is annealed at 400 °C in air. We show evidences that the p-n junction remains good and the oxidation of Mo is the main cause of the cell efficiency degradation. Also we show that the ITO thin film deposited onto Mo avoid the MoO_x formation when the solar cell is annealed at same conditions. All solar cell characteristics are preserved. The solar cells were fabricated in the superstrate configuration by using Glass/ITO/ZnO/CdS/CdTe/back contact layers. The CdTe film was grown by conventional CSS technique. The cells were activated by using CHClF₂-argon-oxygen gases. DRX spectra and HR-SEM were made for Mo/Glass and ITO/Mo/CdTe before and after annealing at 400 °C in air.