Raj, VidurHaggren, TuomasTournet, JulieTan, Hark HoeJagadish, Chennupati2021-11-292574-0962http://hdl.handle.net/1885/251986In recent years, carrier-selective contacts have emerged as an efficient alternative to the conventional doped p−n or p−i−n homojunction for charge carrier separation in high-performance solar cells. However, so far, there has been no development in carrier-selective contacts for GaAs solar cells. This paper proposes an alternative device structure and reports an 18.5% efficient single-junction GaAs solar cell using zinc oxide (ZnO) as an electron-selective contact. A detailed X-ray and ultraviolet photoelectron spectroscopy depth profile analysis is performed to reveal the mechanism of carrier selectivity and improved efficiency compared to homojunction cells grown under similar conditions. Moreover, a detailed loss analysis shows that the fabricated solar cell has the potential to reach more than 25% efficiency with further optimization. The device structure proposed in this paper will provide a route to reduce the complexity and cost of epitaxially grown cells while also allowing for the possibility to fabricate high-efficiency III−V solar cells using low-cost growth techniques (such as closed-space vapor transport and thin-film vapor−liquid−solid) where doping can be extremely challenging.This research was supported by the Australian Research Council. T.H. acknowledges the financial support from The Finnish Cultural Foundation and the Walter Ahlstrom Foundation.application/pdfen-AU© 2021 American Chemical Societycarrier-selective contactIII−V solar cellsZnOGaAs solar cellpassivation2021-02-0910.1021/acsaem.0c026162021-11-28