Case 13718

Low cost self-assembled deterministic quasi-periodic structure (DQPS) for light trapping in thin film silicon solar cells

Keywords:

Light trapping, active absorption layer, self-assembly methods, quasi-periodic, gratings, solar cell, thin film, semiconductors

Applications:

Backside layer of thin-film photovoltaic cells

Problem:
  • Weak absorption of photons with long wavelengths and hence lower energy conversion efficiency in silicon thin films.
  • Difficult to control structural parameters of some materials used as absorptive layers deposited on the backside of cells used to increase the optical path length in thin film silicon, making optimization of light trapping structures difficult.
  • Cost-prohibitive fabrication methods of many materials used as absorptive layers, hence making such materials unsuitable to be scaled up for large area applications.

Technology:

The Deterministic Quasi-Periodic Structure (DQPS) is composed of an active absorption layer, a self-assembled quasi-periodic grating, and a distributed Bragg reflector (DBR). The active layer can be p-n, p-i-n or multi-junction made of semiconductors, converting sunlight into electrical energy. The grating, fabricated by self-assemble methods such as aluminum anodization or block copolymerization, is used to diffract the light into oblique angles. It is comprised of two materials with different refractive indices which form one-dimensional or two-dimensional arrays.

Advantages:
  • Significantly reduces the cost of light trapping structures while increasing performance
  • Nearly 100% reflectivity in the visible and near-infrared range
  • Avoids the use of expensive lithographic fabrication steps
  • Fabrication method is capable of controlling and optimizing structure parameters such as thickness, periodicity, duty cycle and degree of randomness

Inventors:
  • Professor Lionel C. Kimerling (Department of Materials Science and Engineering, MIT)
  • Jurgen Michel (Materials Processing Center, MIT)
  • Anuradha M. Agarwal (Materials Processing Center, MIT)
  • Jifeng Liu (Materials Processing Center, MIT)
  • Xing Sheng (Department of Materials Science and Engineering, MIT) Intellectual Property:

Intellectual Property:
  • U.S. Patent Application Number 12/730665, filed March 24, 2010
  • Publications:

    N/A

    Last revised: April 30, 2013

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