MoO _x back contact for CdS/CdTe thin film solar cells: Preparation, device characteristics, and stability

A novel MoO _x back contact buffer has been successfully developed for thin-film CdS/CdTe solar cells. To achieve a good ohmic contact, water rinse step is necessary in order to remove surface residues from the CdTe surface prior to MoO _x deposition by thermal evaporation. With MoO _x as the high work function buffer, various metals can be used as the electrode to realize an ohmic back contact to pCdTe. Thermal and light soaking stability of CdTe cells is also improved with the MoO _x buffer acting as a diffusion barrier to minimize the interaction between the metal electrode and CdTe. The best performance is obtained with MoO _x/Ni as the back contact for the CdS/CdTe solar cell.