Photovoltage decay measurements on Cu(In,Ga)Se2 solar cells by photo-assisted Kelvin probe force microscopy

We have performed the temporally-averaged photovoltage measurements under intermittent light excitation on Cu(In,Ga)Se 2 [CIGS] solar cells by means of photo-assisted Kelvin probe force microscopy, which we originally proposed, and evaluated a time constant τ for photovoltage decay and a contribution ratio r of fast carrier recombination, the former of which is considered to represent a time constant required for the carrier movement across the potential barriers at the hetero-interfaces in the cell structure.