Flexible Cu(In,Ga)Se2 solar cells fabricated using alkali-silicate glass thin layers as an alkali source material

Flexible Cu(In,Ga)Se2 (CIGS) solar cells were fabricated using alkali-silicate glass thin layers (ASTL) as an alkali source material deposited on various flexible substrates prior to the Mo backcontact layer deposition. Control of univalent alkali metal incorporation into the CIGS layer with the use of ASTL was demonstrated regardless of the presence of other multivalent metal impurities in ASTL. Dramatic enhancement in cell efficiencies using ASTL was observed though the use of excessively thick ASTL led to a degradation in cell performance. The quantum efficiency curves of CIGS solar cells fabricated using ASTL showed enhanced absorption in the long wavelength region. The photovoltaic performance dependence on a variety of substrate materials is also discussed.