Premium
A new class of multi‐bandgap high‐efficiency photovoltaics enabled by broadband diffractive optics
Author(s) -
Wang Peng,
DominguezCaballero Jose A.,
Friedman Daniel J.,
Me Rajesh
Publication year - 2015
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.2516
Subject(s) - band gap , optoelectronics , broadband , photovoltaics , optics , photon , thermalisation , semiconductor , materials science , photovoltaic system , energy conversion efficiency , physics , electrical engineering , engineering , thermodynamics
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. Copyright © 2014 John Wiley & Sons, Ltd.