Use of stainless steel as substrate of thin film solar cells: effect of the deposition of multifunctional layers and back contact

Nowadays, the photovoltaic industry efforts to reduce the cost and increase the production rate are promoting the development of new materials and technologies such as the thin film solar cells. 

The choice of the material substrate for thin film cell is a very important question because of the micron thickness of its layers, which can be hardly affected during or after the deposition process by the nature of the substrate. This paper is focused on an investigation carried out to evaluate how the deposition process of multifunctional layers and back contact affects the stainless steel properties.

The referred work has been made on different stainless steel grades: one austenitic (EN-1.4301) and three ferritics (EN-1.4016, EN-1.4509 and EN-1.4521). Concerning manufacturing of thin film solar cells, there are several deposition technologies, on the present work CIGS technique has been studied. This technology has been chosen owing to its high energetic efficiency and also, its high future expectations. After the deposition of layers, the stainless steels have been characterized in relation to their microstructure and mechanical properties. Avoiding any migration of the steel components to the solar cells layers is a critical issue in order to warranty the final performance of the cells, thus an exhaustive study of migration of steel components has been carried out to analyse the compatibility of the substrate with the following deposition process of the cells layers.

As the main result, the selected stainless steels have shown a good behaviour for the studied application since their microstructures and mechanical properties keep unchanged and moreover, any diffusion from the steel to the layers has not been found.