Nanotextured Surfaces for Self-Cleaning Solar Cells

Technology #15700

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fabrication  process  showing (A)  the nanohole arrays  replicated  from  the  original  nanocone  master, and (B)  second  generation  of  replicated nanocone  arrays  formed  and  released  using  an  anti-adhesion  layer  in  UV-curable poly urethane acrylate (PUA)
Categories
Inventors
Professor Robert Cohen
Department of Chemical Engineering, MIT
External Link (web.mit.edu)
Professor Gareth McKinley
Department of Mechanical Engineering, MIT
External Link (web.mit.edu)
Professor George Barbastathis
Department of Mechanical Engineering, MIT
External Link (mitei.mit.edu)
Hyungryul Choi
Department of Mechanical Engineering, MIT
Kyoo-Chul Park
Department of Mechanical Engineering, MIT
Jeong-Gil Kim
Department of Mechanical Engineering, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Structures for Multifunctional Surface and its Fabrication Process

US Patent 9,469,083
Publications
Multifunctional Inverted Nanocone Arrays for Non-wetting, Self-cleaning Transparent Surface with High Mechanical Robustness
Small, June 2014; 10(12)

Applications

The efficiency of solar photovoltaic cells can be greatly impinged if their surface becomes coated with dust or other such contaminants. The current technology introduces a method of producing nanotextured surfaces that can be used in self-cleaning solar cells, without reducing their strength or the amount of light they can capture.

Problem Addressed

Nanotextured surfaces are materials whose surfaces have been textured at the nanoscale. They are typically structured with nanocones, where the surface is patterned with a series of protrusions; or nanoholes, where it is patterned with a series of holes instead. Depending on the gradient of each cone or hole, the wavelengths of light that pass through the material can be controlled. At the same time, with the application of a suitable chemical coating, the surfaces can be made superhydrophobic -- where the application of water can easily clean the surface thoroughly. However, using existing nanostructure geometries and fabrication methods, these surfaces tend to be weak, able to withstand little more than the touch of a finger.

Technology

The current technology proposes the geometry for a nanohole array that can exhibit superhydrophobicity, extremely low reflectance over a broad range of incident angles of light, as well as increased mechanical robustness over existing structures. The profile, height or period of the pattern is varied in order to optimize for the desired properties.

The technology also proposes a fabrication method that is both simple and cost-effective -- involving a master mold that can be fabricated using any lithography technique, and subsequent etching that does not require any additional material. The process involves applying an anti-adhesion layer to the mold, pressing it into the intended surface, while using vacuum assisted wetting to ensure the pattern is transferred accurately. 

Advantages

  • Ability to optimize nanotextured surfaces for the degree of light transmission, hydrophobicity, or strength desired
  • Ability to fabricate said surface on any given substrate