Fabrication Method to Augment Graphene as a Transparent Conducting Electrode

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a shows a schematic of graphene synthesis and transfer, according to some embodiments. b shows a schematic of PEDOT:PSS spin-coating vs. vapor printing of PEDOT deposition, according to some embodiments.
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Inventors
Professor Karen Gleason
Department of Chemical Engineering, MIT
External Link (web.mit.edu)
Professor Jing Kong
Department of Electrical Engineering and Computer Science, MIT
External Link (www.rle.mit.edu)
Hyesung Park
Department of Electrical Engineering and Computer Science, MIT
Rachel Howden
Department of Chemical Engineering, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Devices comprising graphene and a conductive polymer and related systems and methods

US Patent 9,136,488
Publications
Organic Solar Cells with Graphene Electrodes and Vapor Printed Poly(3,4-ethylenedioxythiophene) as the Hole Transporting Layers
ACS Nano, 2012, 6 (7), pp 6370–6377

Applications

An essential component in the construction of organic solar cells is the Transparent Conducting Electrode (TCE), which serves to conduct electricity within the solar cell. Graphene has emerged as a promising material for TCEs, because of its high transparency and current-carrying capacity, which surpass that of Indium Tin Oxide (ITO), the most widely used TCE today. 

The present technology can be applied towards enhancing the performance of graphene as a TCE, which can thus improve the performance of organic solar cells. As a replacement for the increasingly expensive ITO, it also has the potential to lower the cost of organic solar cells.

Problem Addressed

 A critical factor in optimizing graphene as a TCE is reducing the energy lost between it and the solar cell's electron donor material. With ITO, this issue can be resolved by applying a conducting polymer known as PEDOT:PSS between the TCE and electron donor material. However, fabrication methods thus far have been unable to apply PEDOT:PSS to graphene without impeding its performance. 

Technology

The current technology proposes a method of applying PEDOT to graphene using oxidative chemical vapor deposition, where an unmodified graphene surface is exposed to a vaporized monomer and an oxidizing agent. This method involves a low temperature, moderate pressure and no use of solvents, meaning that the graphene material and its properties are not compromised in the process. The methodology can be applied to graphene films that have been fabricated either by low pressure chemical vapor deposition (LPCVD) or atmospheric chemical vapor deposition (APVCD). 

Advantages

  • Does not require any pre-treatment of the graphene surface
  • Results in performance comparable to ITO treated with PEDOT:PSS
  • Minimizes the performance differences between LPVCD and APVCD graphene
  • Lays PEDOT onto graphene in a single step
  • Allows PEDOT to be applied in a pattern