Limitations of Near Edge X-ray Absorption Fine Structure as a tool for observing conduction bands in chalcopyrite solar cell heterojunctions

► Near Edge X-ray Absorption Fine Structure investigated as tool for probing the conduction band in Cu(In,Ga)S2. ► Absorption edge of anion contains most pertinent electronic information. ► Development of Cu(In,Ga)2 band gap with increased Ga content reflected in anion absorption edge positions. ► Correspondence with theory found.