An approach to MgCl2 activation on CdSe thin films for solar cells

Abstract

The energy demand of the world is rapidly increasing and to cater this, there is a need to explore new renewable energy resources. CdSe thin film solar cells may be promising alternative to the CdTe solar cells which are extensively studied and used in solar cell technology. The pre/post deposition chlorine based treatments (viz. CdCl2, MgCl2, NH4Cl) are the important steps to enhance the performance of Cd-based thin film solar cells. Therefore, a study on MgCl2 activation treatment to CdSe thin films for solar cell applications as absorber layer is undertaken. Different physical properties of e-beam evaporated CdSe films (thickness 550 nm) grown on glass and ITO substrates are investigated and found to be strongly dependent on the post-chlorine treatment. The films have cubic zinc-blende structure and phase transformation from cubic (111) to hexagonal (002) is achieved with the MgCl2 treatment while the optical band gap is reduced. I-V characteristics reveal the linear relation between voltage and current as well as the surface roughness is varied with treatment and improved homogeneity. The deposition of CdSe thin films is confirmed by elemental analysis where Cd and Se were found to be rich with treatment. The investigated results suggest that CdSe thin films treated by MgCl2 and annealed at 320 °C may be a viable alternative absorber layer to the Cd-based solar cells.