13.6%-efficient Cu(In,Ga)Se2 solar cell with absorber fabricated by RF sputtering of (In,Ga)2Se3 and CuSe targets

A conversion efficiency of 13.6% has been achieved in Cu(In,Ga)Se2 (CIGS) thin film solar cell with absorber layer fabricated by sequentially RF sputtering (In,Ga)2Se3 and CuSe targets and further annealing in Se vapor. The significant improvement, comparing with the efficiency of 10.8% for CIGS solar cell sputtering from a quaternary CIGS target, was attributed to smoother surface, better crystallinity, and more compact structure of the CIGS film. The reaction pathway of (In,Ga)2Se3/CuSe bilayer was discussed, and such a bilayer design was demonstrated to be energetically favorable to form a better-crystallized CIGS film.