Exploring co-sputtering of ZnO:Al and SiO 2 for efficient electron-selective contacts on silicon solar cells

Sihua Zhong* (Corresponding Author), Monica Morales-Masis, Mathias Mews, Lars Korte, Quentin Jeangros, Weiliang Wu, Mathieu Boccard, Christophe Ballif

*Corresponding author for this work

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Abstract

In recent years, considerable efforts have been devoted to developing novel electron-selective materials for crystalline Si (c-Si) solar cells with the attempts to simplify the fabrication process and improve efficiency. In this study, ZnO:Al (AZO) is co-sputtered with SiO 2 to form AZO:SiO 2 films with different SiO 2 content. These nanometer-scale films, deposited on top of thin intrinsic hydrogenated amorphous silicon films and capped with low-work-function metal (such as Al and Mg), are demonstrated to function effectively as electron-selective contacts in c-Si solar cells. On the one hand, AZO:SiO 2 plays an important role in such electron-selective contact and its thickness is a critical parameter, with a thickness of 2 nm showing the best performance. On the other hand, at the optimal thickness of AZO:SiO 2 , the open circuit voltage (V OC ) of the solar cells is found to be relatively insensitive to material properties of AZO:SiO 2 . Whereas, regarding the fill factor (FF), AZO without SiO 2 content exhibits to be the optimal choice. By using AZO/Al as electron-selective contact, we successfully realize a 19.5%-efficient solar cell with V OC over 700 mV and FF around 75%, which is the best result among c-Si solar cells using ZnO as electron-selective contact. Also, this work implies that efficient carrier-selective film can be made by magnetron sputtering method.

Original languageEnglish
Pages (from-to)67-73
Number of pages7
JournalSolar Energy Materials and Solar Cells
Volume194
DOIs
Publication statusPublished - 1 Jun 2019

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Keywords

  • UT-Hybrid-D
  • Co-deposition
  • c‐Si solar cells
  • Electron-selective contact
  • Magnetron sputtering
  • AZO

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