21.2% GaAs Solar Cell Using Bilayer Electron Selective Contact

Abstract

GaAs remain one of the crucial materials for solar cell applications as it boasts the world’s highest efficiency single junction solar cells. However, their high cost limits their widespread terrestrial applications. Traditional GaAs solar cells required a complex stack of doped junctions, which could only be grown using epitaxy, which is a very costly technique. Here, we study a non‐epitaxial bilayer of ZnO and TiO2 as electron‐selective contact. We show that a bilayer selective contact could achieve very high performance through interface band engineering and a reduction of the barrier for electron transfer. We achieve 21.2% efficient solar cells, with Voc of 1.04 V, Jsc of 26.13 mA.cm‐2, and a FF of 77.8%. The Voc reported in the paper is comparable to the highest Voc reported for substrate‐based GaAs solar cells of 1.075 V. An experimental loss analysis shows that the device is mainly limited by series and shunt resistance and reflection losses, both of which could further be minimized by optimization of the fabrication process. The results presented will be very useful for the further development of cheaper GaAs solar cells, whereas the bilayer selective contact concept can be implemented for other kinds of solar cells.This article is protected by copyright. All rights reserved.