A Comparative Study of Microstructural Stability and Sulphur Diffusion in CdS/CdTe Photovoltaic Devices

Joel Duenow, A.A. Taylor, J.D. Major, G. Kartopu, D. Lamb, R.G. Dhere, X. Maeder, S.J.C. Irvine, K. Durose, B.G. Mendis

Research output: Contribution to journalArticlepeer-review

34 Scopus Citations

Abstract

The role of CdCl2 activation in the production of high quality CdTe-based photovoltaic devices remains a subject of much debate. In this study, CdTe-based cells produced in three independent laboratories using different device fabrication technologies are investigated before and after CdCl2 activation with regard to structural changes (recrystallisation and grain growth) and sulphur out-diffusion. Using scanning transmission electron microscopy (STEM) and X-ray diffraction it is demonstrated that CdCl2 activation of the investigated cells produces no statistical structural changes to the CdTe. Additionally, energy dispersive spectrometry (EDS) performed in the STEM on the same samples illustrates that the change in sulphur diffusion following activation is more limited than expected from previous studies; no change is detectable when the thermal budget for CdTe deposition is significantly greater than that for activation. This suggests that the efficiency enhancement during CdCl2 treatment is not due to sulphur out-diffusion. Lastly, cathodoluminescence microscopy is used to demonstrate in two dimensions how sulphur diffuses into a model sample and the results are found to be consistent with STEM-EDS. Some spectroscopic evidence for enhanced sulphur diffusion along grain boundaries is also observed.

Original languageAmerican English
Pages (from-to)341-349
Number of pages9
JournalSolar Energy Materials and Solar Cells
Volume141
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier B.V.

NREL Publication Number

  • NREL/JA-5K00-64674

Keywords

  • Cathodoluminescence
  • CdTe/CdS photovoltaics
  • EDS
  • STEM
  • Sulphur diffusion

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