Methods for Fabricating Devices Including Photovoltaic Devices

Technology #15160

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Inventors
Professor Karen Gleason
Department of Chemical Engineering, MIT
External Link (web.mit.edu)
Professor Vladimir Bulovic
Department of Electrical Engineering and Computer Science, MIT
External Link (onelab.mit.edu)
Miles Barr
Department of Chemical Engineering, MIT
David Borrelli
Department of Chemical Engineering, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Methods for Fabricating Devices Including Photovoltaic Devices

US Patent Pending US 2013-0189807
Publications
Oxidative Chemical Vapor Deposition of Semiconducting Polymers and their use in Organic Photovoltaics
MIT, June 2014

Applications

Oxidative chemical vapor deposition (oCVD) results in heavily doped conductive polymer films using materials that are insoluble and infusible. oCVD of conjugated polymers can be used to create photoactive semiconductors in organic solar cells.

Problem Addressed

Vacuum fabrication of multilayered devices is not constrained by the requirement of finding orthogonal solvents to prevent mixing between layers during deposition. However, the high temperatures necessary to physically deposit polymers by vacuum thermal evaporation leads to polymer degradation, limiting materials to low-molecular weight organics. oCVD offers the benefits of vacuum processing, including parallel and sequential deposition, well-defined thickness control and uniformity, and inline integration with other standard vacuum processes (e.g. vacuum thermal evaporation). Additionally, oCVD is conformal over nonplanar substrates, enabling compatibility with substrates such as paper and textiles.

Technology

The present technology demonstrates the use of oCVD to process conjugated polymers (including insoluble polymers) via vacuum deposition.  In this case, oCVD was used to obtain polythiophene (PT) by reacting thiophene monomer vapor with iron (III) chloride via oxidative polymerization to obtain a doped, conductive form of the polymer. Upon rinsing the film with methanol, the polythiophene was dedoped to obtain the semiconducting form. This polymer was deposited onto ITO-glass substrates (indium tin oxide) and successfully incorporated into efficient bilayer heterojunction photovoltaic devices with C60 (fullerene), resulting in power conversion efficiencies up to 0.8%.

Advantages

  • Combines the benefits of vacuum processing and semiconducting polymers
  • Allows processing of polymer active layers without solubility, temperature, or substrate constrains