Electrical activity at grain boundaries of Cu In,Ga Se2 thin films

There is a renewed interest in the electrical activity at grain boundaries in relation to the outstanding performance of thin film solar cells on the basis of Cu In,Ga Se2 . We observed electrical activity at grain boundaries of CuGaSe2 thin films by locally resolved work function measurements, using Kelvin probe force microscopy in ultra high vacuum on in situ prepared surfaces. By means of their electrical activity under illumination, we identify different types of grain boundaries, presumably associated to different crystallite orientations. A comprehensive discussion on the applicability of different models is presente