CuInSe2 formation through Cu2Se–In3Se2 multilayer structures prepared by thermal evaporation technique

• Cu2Se/In3Se2 multilayer structure deposited by thermal evaporation technique for CIS solar cells.
• Increase in number of layers improves the crystallinity and the formation of CIS.
• Formation of CIS composite by simple by thermal evopration technique.

The current study investigates the Cu2Se/In3Se2 multilayer structure deposited by thermal evaporation technique for CIS solar cells with different number of layers. The X-ray diffraction pattern reveals that the layer thickness improves the crystallinity and the formation of CIS for the 30 layer films through photoluminescence (PL) emission. The optical band gap values are found to be 2.87 eV and 2.79 eV for 5 and 10 period films respectively. The splitted band gap ranging 1.30 and 2.25 eV for 15 periods and decrease in the band gap values are due to large grains. This splitting is due to quantum size effect and CIS composite formation. The vibration frequency at 174.54 cm−1 is evident for formation of CuInSe2 Chalcopyrite phase.