Amorphous transparent conductors for PV applications

Transparent conducting oxides (TCOs) with qualitatively better resistance to humidity than ZnO, the traditional Cu(In,Ga)Se₂ (CIGS) TCO, are needed to reduce the water-induced degradation of CIGS photovoltaics (PV). Amorphous In-Zn-O (a-IZO) is found both to act as a water vapor transport barrier and to be essentially inert in damp heat testing at 85°C, 85%RH (85/85). In particular, no significant reduction in conductivity or transparency was observed after 40 days at 85/85. In initial PV application testing, a-IZO-finished CIGS solar cells have demonstrated 16.4% efficiency, essentially equal to equivalent CIGS cells finished with Al-doped ZnO.