A better understanding of Cbd-Zn(S,O) using hydrogen peroxide as an additive

This paper explores the influence of hydrogen peroxide H₂O₂ on the chemical bath deposition of zinc oxisulfide Zn(S,O) and the final photovoltaic performances of the Cu(In,Ga)Se₂-based (CIGSe) associated device. First, the influence of H₂O₂ on Zn(S,O) deposition rate and growth mechanism is studied with theoretical considerations and in situ quartz crystal microgravimetry measurements. It shows that hydrogen peroxide concentration masters the deposition rate and induces a “cluster-by-cluster” mechanism. Morphology and composition of Zn(S,O) films have been investigated by scanning electron microscopy and X-Ray photoelectron spectroscopy techniques. In a second part the optimized process is then on co-evaporated Cu(In,Ga)Se₂ substrates and solar cells are completed with a (Zn,Mg)O/ZnO:Al window layers. The use of H₂O₂ leads to lower efficiency than CdS-based reference, which can be explained by an oxidation of the CIGSe surface.