Progress toward 20% efficiency in Cu(In,Ga)Se2 polycrystalline thin-film solar cells

摘要

This short communication reports on achieving18.8% total-area conversion efficiency for aZnO/CdS/Cu(In,Ga)Se2/Mo polycrystalline thin-film solar cell.We also report a 15%-efficient, Cd-free device fabricated viaphysical vapor deposition methods. The Cd-free cell includesno buffer layer, and it is fabricated by direct deposition of ZnOon the Cu(In,Ga)Se2 thin-film absorber. Both results have beenmeasured at the National Renewable Energy Laboratoryunder standard reporting conditions (1000W/m2, 25oC, ASTME892 Global). The 18.8% conversion efficiency represents anew record for such devices (Notable Exceptions) and makesthe 20% performance level by thin-film polycrystallinematerials much closer to reality. We allude to theenhancement in performance of such cells as compared toprevious record cells, and we discuss possible and realisticroutes to enhance the performance toward the 20% efficiency level.