Ultrathin transparent metal capping layer on metal oxide carrier-selective contacts for Si solar cells

Carrier-selective contacts using metal oxide thin films have been proposed and successfully demonstrated for dopant-free Si solar cells. However, the electronic properties of several metal oxide thin films such as MoOx\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {MoO}_{\mathrm{x}}$$\end{document} can deteriorate easily due to the modification of surface chemical state upon exposure to ambient air. Here, we report the use of an ultrathin Au capping layer on MoOx\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {MoO}_{\mathrm{x}}$$\end{document} to mitigate the undesired surface chemistry modification. In addition, the Au capping layer also functions as a transparent conducting electrode, thereby potentially allowing the replacement of transparent conductive oxides such as indium tin oxide. We further show that the power conversion efficiency of a simple Au/MoOx\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {MoO}_{\mathrm{x}}$$\end{document}/n-Si device increases from 0.53 to 6.43% with the incorporation of a grid type electrode at the front surface. Our results provide insights into the design of efficient solar cells incorporating carrier selective contacts without the need to use transparent conductive oxides.