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

Abstract

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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> :Na buffer layer we have reached the 18% efficiency level for 30×30cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> champion modules with a new externally certified record efficiency of 17.93% We show how a combination of a wider band gap In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> :Na buffer layer with a Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Mg <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> module efficiencies of our In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Sy:Na-buffered stack.