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

A novel MoOx 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 MoOx deposition by thermal evaporation. With MoOx as the high work function buffer, various metals can be used as the electrode to realize an ohmic back contact to p–CdTe. Thermal and light soaking stability of CdTe cells is also improved with the MoOx buffer acting as a diffusion barrier to minimize the interaction between the metal electrode and CdTe. The best performance is obtained with MoOx/Ni as the back contact for the CdS/CdTe solar cell.

► Water rinse of CdTe surface is critical for the formation of ohmic contact with MoOx as back contact buffer.
► MoOx should be deposited by thermal evaporation method.
► Device stability depends on the work function of metal electrode.
► The best back contact formation is MoOx/Ni.