Recent advances in electrodeposition of interfacial buffer layers in chalcopyrite-based solar cells

Soft chemical processes such as screen printing, sol-gel, electrochemical or chemical bath-deposition, enable low cost and easily scalable processes for thin layer solar cells. For the CIGSe based solar cells, with the standard Mo/Cu(In,Ga)Se₂/CdS/i-ZnO/n⁺-ZnO structure, all layers of the p-n heterojunction and the transparent conductive oxide window can be grown by aqueous solution processes. Based on our previous work and the literature it was shown that cells with electrodeposited Cu(In,Ga)(S,Se)₂-based absorbers can present conversion efficiencies up to 13.8 %. When ZnO:Cl window layer is deposited by electrodeposition with a coevaporated CIGS-based absorber, efficiency above 15% can be reached. In this work we will mainly focus on the application of this soft deposition technique for the preparation of the buffer layer. Electrochemical investigation of In-S layers is carried out. XPS analysis show the presence of both S and O. Conversion efficiencies of complete devices up to 9.5 % are obtained.