Case 14319

Recycling of Compound Semiconductor Photovoltaics by Means of Ambipolar Eletrolysis

Keywords:

Ambipolar electrolysis (AE), Compound Semiconductor, CdTe recycling

Applications:

Recycling of spent or waste compound semiconductor materials, such as CdTe used in solar cells

Problem:
  • Toxicity and environmental impact of Cd and Te, which is widely used in thin film solar cells
  • Multiple steps required by current recycling methods

Technology:

The invention provides a new method to recycle compound semiconductor materials used in the photovoltaic industry using ambipolar electrolysis (AE). The proposed process selectively dissolves the semiconductor material off of the solar cell into a molten salt bath, leaving behind the glass and metal wire contacts. AE can then be performed on the molten salt containing the dissolved compound, resulting in the simultaneous electro-deposition of the two metals onto separate electrodes. To recycle CdTe, the molten salt can be CdI2 or CdCl2-KCl, and the operating temperature is at 500C. Given the high purity of the collected molten metals, Cd and Te products could be remixed under N2, producing CdTe, ready to be reintroduced into the manufacturing stream of new solar cells.

Advantages:
  • Simple one-step process for the reclamation of Cd and Te
  • Closed-stream recycling where the products can be reintroduced into the manufacturing cycle

Inventors:
  • Professor Donald R. Sadoway (Department of Materials Science and Engineering, MIT)
  • Dr. Sebastian Osswald (Department of Materials Science and Engineering, MIT)
  • David J. Bradwell (Department of Materials Science and Engineering, MIT)

Intellectual Property:
  • US Utility Patent Application 13/194391, filed on July 29, 2011

Publications:

Recycling ZnTe, CdTe, and Other Compound Semiconductors by Ambipolar Electrolysis: David J. Bradwell, Sebastian Osswald, Weifeng Wei, Salvador A. Barriga, Gerbrand Ceder, and Donald R. Sadoway Journal of the American Chemical Society 2011 133 (49), 19971-19975

Last revised: April 9, 2012

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