Optimization of Thin Film Thicknesses in Tandem Solar Cells

This paper contains experimental investigation regarding fabrication and characterization of a Nano-layered tandem solar cell. Bi-junction solar cell was fabricated using Electron Beam (E-Beam) Coater and Thermal Evaporator. Cuprous oxide (Cu₂O) and Copper Phthalocyanine (CuPc) were coated as P-type active layers while titanium dioxide (TiO₂) was used as an N-type layer in both sub-cells. The thickness of active P-type layers (Cu₂O and CuPc) and N-type layer (TiO₂) was varied to see its effect on light absorption and transmission. The lattice mismatch between adjacent layers was also studied to see its effect on solar cell efficiency. Moreover, the effect of coating thickness on open circuit voltage and short circuit current was also evaluated. An increment in the efficiency of the solar cell was observed with increase in the layer thickness of CuPc and decrease in thickness of TiO₂.