A novel method is described for the patternwise metallization of amorphous silicon solar cells, based on photocathodic deposition. The electric field of the p-i-n structure is used for the separation of photogenerated charge carriers. The electrons are driven to the interface of the n+-layer with the solution where they reduce metal ions to metal. The large difference between the conductivity of dark and illuminated areas and the high sheet resistance of the n-type layer makes it possible to define a metal pattern by selective illumination. It is shown that both nickel and gold patterns can be deposited using this method. After annealing, an ohmic nickel contact is formed and the cell exhibits good photovoltaic characteristics.
Kooij, E. S., Hamoumi, M., Kelly, J. J., & Schropp, R. E. I. (1997). Photoselective Metal Deposition on Amorphous Silicon p-i-n Solar Cells. Journal of the Electrochemical Society, 144(10), L271-L272. https://doi.org/10.1149/1.1838005