ZnO/CdS/Cu(In,Ga)Se2 thin film solar cells with improved performance

This paper reports results from experiments concerning the growth of CuInSe₂ films on different substrate materials, uncoated, and coated with molybdenum. Specifically the effect on the structure, i.e. preferred orientation, of the polycrystalline films is investigated. It is found that soda-lime float glass results in the most oriented films and also that the highest solar cell conversion efficiency is obtained with devices made from such films. In another set of experiments the effect of various deposition conditions for the ZnO window layer is studied. It is found that optimum performance is not strongly dependent on the deposition process. The highly doped part of the window, ZnO:Al, has been replaced with ITO on some devices and a comparison is made. Finally, ZnO/CdS/CuInSe₂ and ZnO/CdS/Cu(In,Ga)Se₂ thin film devices exhibiting active area conversion efficiencies of 15.4% and 16.9%, respectively, are demonstrated