MRS Bulletin

Photon Management for Photovoltaics

Photon Management for Photovoltaics

High-performance antireflection coatings utilizing nanoporous layers

David J. Poxsona1, Mei-Ling Kuoa2, Frank W. Monta3, Y.-S. Kima4, Xing Yana5, Roger E. Welsera6, Ashok K. Sooda7, Jaehee Choa8, Shawn-Yu Lina9 and E. Fred Schuberta10

a1 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; poxsod@rpi.edu

a2 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; kuom@rpi.edu

a3 Raydex Technology, Inc., Cambridge MA 02138; montf@raydextech.com

a4 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; kimy10@rpi.edu

a5 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; yanx@rpi.edu

a6 Magnolia Solar, Inc.; rwelser@magnoliasolar.com

a7 Magnolia Solar Inc.; aksood@magnoliasolar.com

a8 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; choj6@rpi.edu

a9 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; sylin@rpi.edu

a10 Rensselaer Polytechnic Institute, Troy, NY 12180, USA; efschubert@rpi.edu

Abstract

To harness the full spectrum of solar energy, optical reflections at the surface of a solar photovoltaic cell must be reduced as much as possible over the relevant solar spectral range and over a wide range of incident angles. The development of antireflection coatings embodying omni-directionality over a wide range of wavelengths is challenging. Recently, nanoporous films, fabricated by oblique-angle deposition and having tailored- and very low-refractive index properties, have been demonstrated. Tailorability of the refractive index and the ability to realize films with a very low-refractive index are properties critical in the performance of broadband, omnidirectional antireflection coatings. As such, nanoporous materials are ideally suited for developing near-perfect antireflection coatings. Here, we discuss multilayer antireflection coatings with near-perfect transmittance over the spectral range of 400−2000 nm and over widely varying angles of acceptance, 0−90°. The calculated solar optical-to-electrical efficiency enhancement that can be attained with nanoporous multilayer coatings over single-layer quarter-wave films is 18%, making these coatings highly attractive for solar cell applications.

Key Words:

  • Nanoscale;
  • thin film;
  • optical;
  • photovoltaic
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