The formation of CuIn(S,Se)2 thin film solar cell absorbers from electroplated precursors

In this article structural properties as well as morphological aspects of CuIn(S,Se)(2) thin film solar cell absorbers, produced by annealing of electroplated precursors, are discussed. Real-time X-ray diffraction (XRD) experiments while precursor annealing have shown, that a reduced amount of electrodeposited selenium is the key parameter to realize a chalcopyrite formation mechanism similar to the one known for sputtered stacked elemental layer (SEL) precursors. Absorber layers processed from precursors produced by simultaneous electrodeposition of copper, indium and selenium show a preferable absorber morphology with an average grain size on the micrometer scale when the electrochemically deposited amount of selenium is reduced to [Se] / [In] = 0.1. The amount of selenium, missing for the formation of a stoichiometric chalcopyrite, was deposited in a second process step prior to precursor annealing. Solar cells produced from these absorbers show light conversion efficiencies up to 10%.