Junction formation by Zn(O,S) sputtering yields CIGSe-based cells with efficiencies exceeding 18%

In an effort to reduce the complexity and associated production costs of Cu(In,Ga)Se2 (CIGSe)-based solar cells, the commonly used sputtered undoped ZnO layer has been modified to eliminate the requirement for a dedicated buffer layer. After replacing the ZnO target with a mixed ZnO/ZnS target, efficient solar cells could be prepared by sputtering directly onto the as-grown CIGSe surface. This approach has now been tested with high-quality lab-scale glass/Mo/CIGSe substrates. An efficiency of 18.3% has been independently confirmed without any post-deposition annealing or light soaking.