Three stage evaporation of Cu In,Ga S2 solar cell absorber films without KCN treatment and Na control

Abstract

Cu poor Cu In,Ga S2 films have been prepared by three stage sequential evaporation In,Ga S Cu S In,Ga S on Mo covered soda lime glass without Na control. The depth profiles of O and Na in the grown films were investigated by secondary ion mass spectroscopy SIMS . It has been found that the O concentration was constant in the bulk, and decreased close to the surface comparable to the case of the two stage process. The observed depth profile of Na resembles that of O. The correlation of the depth profiles between O and Na is again indicated. The efficiencies of solar cells from the O2 annealed Cu rich Cu In,Ga S2 films did not increase, but the efficiencies of some solar cells prepared from Cu poor Cu In,Ga S2 films increased when the absorber was annealed in oxygen. The best efficiency of a solar cell from our O2 annealed Cu poor Cu In,Ga S2 films was 9.3 no antireflection coating without KCN treatment and Na contro