Chemical and Structural Characterization of Cu(In,Ga)Se2/Mo Interface in Cu(In,Ga)Se2 Solar Cells

Interfaces between the Cu(In,Ga)Se2 (CIGS) absorber and the Mo back contact in CIGS solar cells were investigated by secondary ion mass spectroscopy (SIMS) and analytical transmission electron microscopy (TEM). The solar cell with MgF2/ITO/ZnO/CdS/CIGS/Mo/glass structure exhibited an efficiency of over 15%. In the SIMS depth profile, the Se intensity had a peak at the CIGS/Mo interface. Cross-sectional TEM observation showed that there were two layers at the interface. One was a MoSe2 layer and the other was an amorphous layer. The thickness of the interface layers depends on the deposition conditions of the Mo layers.