Electrodeposition of CuInSe2 layers using a two-electrode system for applications in multi-layer graded bandgap solar cells

In order to develop low-cost, large area multi-layer graded bandgap solar cell structures, CuInSe2 layers were grown using a simplified two-electrode system. Atomic force microscopy (AFM) shows the layers grown consist of nano- and micro- size particles. Photoelectrochemical (PEC) cell, X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF) measurements confirm that it is possible to grow CuInSe2 layers with p-, i- and n-type electrical conduction, as pre-determined for applications in multi-layer device structures. XRF, XPS and PEC measurements show that Cu-richness provides p-type conduction and In-richness provides n-type conduction in electrodeposited CuInSe2 layers. It is also possible to grow materials with different bandgaps in the range 1.00–1.90 eV. The combination of these two properties allows growth of multi-layer structures and preliminary work on these devices show good rectifying properties and exhibit photovoltaic activity. These new developments will be presented in this paper.