Advanced PVD buffers on the road to GW-scale CIGSSe production

Two R&D approaches for advanced Cd-free PVD buffer layers in our CIS device stack are demonstrated in the present contribution allowing to address the goal of the CIGSSe PV industry of increased module conversion efficiencies and/or reduced Capex and Opex costs for further production capacity expansion. With our In
_x
S
_y
:Na buffer layer we have reached the 18% efficiency level for 30×30cm
²
champion modules with a new externally certified record efficiency of 17.93% We show how a combination of a wider band gap In
_x
S
_y
:Na buffer layer with a Zn
_1-x
Mg
_x
O i-layer will lead to further efficiency improvements. In a second approach, we illustrate that the conversion efficiency of a simplified Zn(O,S)/ZnO:Al all-sputtered buffer and TCO stack on our CIGSSe absorber is already within reach of the 30×30cm
²
module efficiencies of our In
_x
Sy:Na-buffered stack.