A study was made of the electronic properties of grain boundaries in polycrystalline Cu(In,Ga)Se2 thin films by means of Kelvin probe force microscopy. As-grown as well as KCN-treated films were investigated comparatively. No influence of the chemical treatment on the electronic properties of grain boundaries was found. Grain boundaries generally exhibited large variations in their electronic properties. By means of a novel method of data analysis both potential barriers for holes and electrons were found at grain boundaries, in a range from -118 to 114mV, as well as grain boundaries without potential barrier. No dependence of the electronic grain-boundary properties on the Ga-content was detected. Consequently, it was concluded that there was no correlation between the electronic properties of grain boundaries and the obtained maximum efficiencies of Cu(In,Ga)Se2 thin film solar cells as a function of the Ga content.

Electronic Properties of Grain Boundaries in Cu(In,Ga)Se2 Thin Films with Various Ga-Contents. R.Baier, J.Lehmann, S.Lehmann, T.Rissom, C.A.Kaufmann, A.Schwarzmann, Y.Rosenwaks, M.C.Lux-Steiner, S.Sadewasser: Solar Energy Materials and Solar Cells, 2012, 103, 86-92