A New Class of Multi-Bandgap High-Efficiency Photovoltaics Enabled by Broadband Diffractive Optics

Daniel Friedman, Peng Wang, Jose Dominguez-Caballero, Rajesh Menon

Research output: Contribution to journalArticlepeer-review

41 Scopus Citations


A semiconductor absorber with a single bandgap is unable to convert broadband sunlight into electricity efficiently. Photons with energy lower than the bandgap are not absorbed, whereas those with energy far higher than the bandgap lose energy via thermalization. In this Article, we demonstrate an approach to mitigate these losses via a thin, efficient broadband diffractive micro-structured optic that not only spectrally separates incident light but also concentrates it onto multiple laterally separated single-junction semiconductor absorbers. A fully integrated optoelectronic device model was applied in conjunction with a nonlinear optimization algorithm to design the optic. An experimental demonstration is presented for a dual-bandgap design using GaInP and GaAs solar cells, where a 20% increase in the total electric power is measured compared with the same cells without the diffractive optic. Finally, we demonstrate that this framework of broadband diffractive optics allows us to independently design for the number of spectral bands and geometric concentration, thereby enabling a new class of multi-bandgap photovoltaic devices with ultra-high energy conversion efficiencies.

Original languageAmerican English
Pages (from-to)1073-1079
Number of pages7
JournalProgress in Photovoltaics: Research and Applications
Issue number9
StatePublished - 2015

Bibliographical note

Publisher Copyright:
Copyright © 2014 John Wiley & Sons, Ltd.

NREL Publication Number

  • NREL/JA-5J00-65127


  • diffractive optics
  • microstructures
  • multi-bandgap photovoltaics
  • solar concentrator
  • spectrum-splitting


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