Low-refractive-index nanoparticle interlayers to reduce parasitic absorption in metallic rear reflectors of solar cells

Mathieu Boccard, Peter Firth, Zhengshan Yu, Kathryn C. Fisher, Mehdi Leilaeioun, Salman Manzoor, Zachary Holman

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Metal reflectors or electrodes in contact with optoelectronic devices can induce parasitic light absorption. A low-refractive-index (low-n) layer inserted between the metal reflector and the optically active layer(s) reduces this absorption. We investigate the use of porous, nanoparticulate films as low-n layers, and fabricate silicon solar cells with nanoparticle/silver rear reflectors. We vary the porosity and thus n (between 1.1 and 1.5) of the nanoparticle films, which are deposited by a controllable aerosol spray process, and investigate their effectiveness in reducing infrared parasitic absorption in the solar cells. Optical test structures incorporating films with the highest n exhibit an internal reflectance of over 99%, matching best-in-class structures; lower-n layers should in theory perform better still but their rougher surfaces appear to induce plasmonic absorption in the overlying silver layer. No loss in open-circuit voltage or fill factor is observed when applying the best nanoparticle films in silicon heterojunction solar cells, enabling efficiencies similar to those achieved with reference cells that employ a thick indium tin oxide layer between the wafer and the rear silver electrode.

Original languageEnglish (US)
Article number1700179
JournalPhysica Status Solidi (A) Applications and Materials Science
Issue number10
StatePublished - Oct 2017


  • light management
  • parasitic absorption
  • reflectors
  • silicon
  • solar cells

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry


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