Impact of sodium on the secondary phases and current pathway in Cu2(Zn,Sn)Se4 thin film solar cell

Yi Cheng Lin, Chien Mu Lai, Hung Ru Hsu

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Abstract

In this study, we investigated the influence of Na content on secondary phases and current pathway in Cu2(Zn,Sn)Se4 (CZTSe) thin film solar cells with the following structure: Ti/Mo:Na/Mo/CZTSe/CdS/i-ZnO/ZnO:Al/Al. The application of Na-doped Mo target as a source of sodium. Experimental results demonstrate that increasing the Na content leads to an increase in the quantity of secondary phase SnSe2 on the surface of the absorber layer; however, it did not appear to affect the secondary phases of Cu2SnSe3 (CTSe) or ZnSe. Excessive quantities of Na were shown to have an adverse effect on device efficiency. Our results using conductive atomic force microscopy (C-AFM) revealed that an increase in the quantity of secondary phase SnSe2 can shift the current pathway on the surface of CZTSe from CZTSe grain boundaries (GBs) to the SnSe2 grains. The role of secondary phase SnSe2 of the CZTSe acted as a channel for the current flow, which results in high leakage current and low device efficiency.

Original languageEnglish
Pages (from-to)131-137
Number of pages7
JournalMaterials Chemistry and Physics
Volume192
DOIs
Publication statusPublished - 2017 May 1

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

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