Abstract
The front transparent conductive oxide layer is a source of significant optical and electrical losses in silicon heterojunction solar cells because of the trade-off between free-carrier absorption and sheet resistance. We demonstrate that hydrogen-doped indium oxide (IO:H), which has an electron mobility of over 100 cm2/V s, reduces these losses compared to traditional, low-mobility transparent conductive oxides, but suffers from high contact resistance at the interface of the IO:H layer and the silver front electrode grid. This problem is avoided by inserting a thin indium tin oxide (ITO) layer at the IO:H/silver interface. Such IO:H/ITO bilayers have low contact resistance, sheet resistance, and free-carrier absorption, and outperform IO:H-only or ITO-only layers in solar cells. We report a certified efficiency of 22.1% for a 4-cm2 screen-printed silicon heterojunction solar cell employing an IO:H/ITO bilayer as the front transparent conductive oxide.
Original language | English (US) |
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Pages (from-to) | 151-156 |
Number of pages | 6 |
Journal | Solar Energy Materials and Solar Cells |
Volume | 115 |
DOIs | |
State | Published - 2013 |
Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by the European Community's FP7 Programme under the 20plµs Project (Grant agreement No. 256695 ), the Swiss Federal Energy Office, and Axpo Naturstrom Fonds, Switzerland . We gratefully acknowledge Roth and Rau Switzerland for both financial support and wafer preparation. We thank Fernando Zicarelli for his screen-printing expertise.
Keywords
- Contact resistance
- Indium oxide
- Indium tin oxide
- Silicon heterojunction
- Solar cell
- Transparent conductive oxide
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films