Stability of Chemically Doped Nanotube-Silicon Heterojunction Solar Cells: Role of Oxides at the Carbon-Silicon Interface

Research output: Contribution to journalResearch articleContributedpeer-review


  • Daniel D. Tune - , Karlsruhe Institute of Technology (Author)
  • Hiroyuki Shirae - , Waseda University (Author)
  • Vincent Lami - , Heidelberg University  (Author)
  • Robert J. Headrick - , Rice University (Author)
  • Matteo Pasquali - , Rice University (Author)
  • Yana Vaynzof - , Heidelberg University  (Author)
  • Suguru Noda - , Waseda University (Author)
  • Erik K. Hobbie - , North Dakota State University (Author)
  • Benjamin S. Flavel - , Karlsruhe Institute of Technology (Author)


Heterojunctions of carbon nanotubes interfaced with silicon and doped with AuCl3 can achieve attractive power conversion efficiencies when operated in the photovoltaic regime; however, the cost and long-term stability of such devices must be improved before they could become commercially viable. Here, we investigate the role of chemical treatment of the carbon nanotube/silicon interface with either SOCl2 or HNO3, prior to AuCl3 doping, on the stability of the photovoltaic devices. We find that while both treatments initially lead to similar device performance, devices treated with HNO3 are significantly more stable. Using X-ray photoemission spectroscopy, we demonstrate that pretreatment with the powerful organic oxidant SOCl2 generates a variety of low-oxidation-state silicon species at the nanotube-silicon interface that are not generated by exposure to HNO3. These species and their evolution over time are implicated in the reduced device stability, highlighting the importance of silicon oxidation states in determining the stability of carbon nanotube-silicon photovoltaic devices.


Original languageEnglish
Pages (from-to)5925-5932
Number of pages8
JournalACS applied energy materials
Issue number8
Publication statusPublished - 26 Aug 2019
Externally publishedYes