Cu(In1-x, Gax)Se2-Based Thin Film Solar Cells Using Transparent Conducting Back Contacts

Cu(In 1- x , Ga x )Se 2 (CIGS)-based thin film solar cells have been fabricated using a transparent conducting oxide (TCO) back contact. The cell performance of CIGS devices using tin oxide (SnO 2 ) and indium tin oxide (ITO) back contacts was almost the same as that of a conventional CIGS solar cell fabricated using Mo back metal electrodes. The CIGS/TCO contacts showed ohmic behavior at room temperature. The optical transmission of the CGS solar cell rises at 740 nm, which corresponds to the band-gap energy of the CGS absorber layer, resulting in a semitransparent behavior in red wavelength regions. These results suggest that this type of CIGS-based solar cell has potential for use in CIGS-based tandem solar cells and other applications.