Office for Technology Commercialization

Selective Removal of Impurities in Light Absorber Substrates

Technology #20160046

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Lee Penn, PhD
Associate Professor, Department of Chemistry
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Eray Aydil, PhD
Professor, Department of Chemical Engineering and Materials Science, College of Science and Engineering
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Managed By
Larry Micek
Technology Licensing Officer 612-624-9568
Patent Protection

US Patent Pending

Chalcogenide Impurities Removal

An etching process can selectively remove chalcogenide impurities that plague Copper Zinc Tin Sulfide (CZTS) and Copper Indium Gallium Selenide (CIGS), important light absorber materials used in thin film solar cell devices. Even small amounts of these impurities, such as copper sulfide and copper selenide, can render photovoltaic devices unusable. The novel solvent mixture, which is at least as effective as current approaches, selectively removes these impurities in just 20 minutes.

Safer Thin Film Solar Cell Purification

Current methods to remove impurities from CZTS and CIGS thin films require either potassium cyanide (KCN) or hydrazine, both highly hazardous, toxic chemicals that may create additional harmful byproducts when used. The new approach uses significantly less toxic mercaptoethanol and ethylenediamine reagents, making it a safer and greener substitute for removing copper sulfide and copper selenide impurities.


  • More effective at selective removal of impurities
  • Mercaptoethanol and ethylenediamine reagents are safer and easier to handle
  • Purifies CIGS and CZTS thin film solar cells


  • CIGS and CZTS thin film solar cells
  • Improved thin films for use in photovoltaic cells
  • Dissolution of various chalcogenides
  • Coating/printing of chalcogenide materials
  • Patterning of chalcogenide structures by etching

Phase of Development Proof of concept