Dry vacuum buffers for industrial chalcopyrite absorbers from a sequential absorber process route

First results are presented for chalcopyrite solar cells with Cd-free dry buffer layers prepared by two different vacuum deposition techniques on sequentially processed Cu(In, Ga)(S, Se) 2 absorbers. The deposition techniques are namely thermal evaporation of In 2 S 3 compound powder and the reactive sputtering of Zn(O, S) layers. Both approaches are suitable for an in-line assembly into an industrial production line. The influence of the variation of process parameters such as buffer layer thickness and annealing time on current-voltage characteristics and quantum efficiency is shown. Best cell results exceed 14% conversion efficiency for the In 2 S 3 approach (>11% for the Zn(O, S) approach) which is comparable but slightly less than the standard CdS reference cells (>15%).