Cu(In,Ga)(S,Se)2 Solar Cell with Zn(O,S,OH)x, Buffer on Stainless Steel Utilizing Zn1-xMgxO and Zn1-xMgxO:Al

Flexible, lightweight, and Cd-free Cu(In,Ga)(S,Se)(2) (CIGSSe) solar cells on stainless steel (SUS) substrates were constructed by utilizing very thin Zn(O,S,OH)(x). 1st buffer, sputtered Zn1-xMgxO 2nd buffer, and sputtered Zn1-xMgxO:Al transparent conductive oxide (TCO) layers. It is disclosed that the high-resistivity Zn0.84Mg0.16O 2nd layer is important to avoid direct contact between the CIGSSe layer and sputtered TCO, thus improving the junction quality, implied by the increased carrier lifetime, and enhancing the photovoltaic performances. Furthermore, the Mg content in the TCO was investigated and optimized to be 0.16, which plays a vital role in improving the photovoltaic performances, resulting from the improved total band alignment. In addition, use of the 2nd buffer and TCO layers with a large energy gap increases the current density. Based on both experimental and numerical results, the near-surface CIGSSe carrier recombination is reduced in devices with Zn0.84Mg0.16O 2nd buffer and Zn0.84Mg0.16O:Al TCO. Ultimately, the conversion efficiency (eta) of the device is enhanced to 17.9%.

Automated summary

Flexible, lightweight, and Cd-free CIGSSe solar cells on stainless steel substrates were fabricated using special buffer and TCO layers. By optimizing the material composition, the photovoltaic performances of the devices can be improved, and carrier recombination can be effectively reduced.