The iron-ion doped Cu(In, Ga)Se2 thin films were prepared on flexible stainless steel substrates via a non-vacuum spin-coating process. The influence of iron-ion doping in the morphology and properties of Cu(In, Ga)Se2 solar cells was investigated in detail. When the molar ratio of iron ions to the total amount of indium and gallium ions in Cu(In, Ga)Se2 was increased, the grain sizes of the Cu(In, Ga)Se2 thin films were reduced and the grain morphology became angular. Iron-ion doping in Cu(In, Ga)Se2 thin films substantially facilitated the formation of grain boundaries and additional shunt paths, leading to high probability of electron-hole recombination. As a result, the conversion efficiency of the prepared Cu(In, Ga)Se2 solar cells decreased dramatically due to iron-ion doping.

Keywords: Flexible substrate, Stainless steel, CIGS solar cell, Selenization, Electron-hole recombination.