Mechanically stacked four-junction concentrator solar cells

Myles A. Steiner, John F. Geisz, J. Scott Ward, Ivan Garcia, Daniel J. Friedman, Richard King, Philip T. Chiu, Ryan M. France, Anna Duda, Waldo J. Olavarria, Michelle Young, Sarah R. Kurtz

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Multijunction solar cells can be fabricated by bonding together component cells that are grown separately. Because the component cells are each grown lattice-matched to suitable substrates, this technique allows alloys of different lattice constants to be combined without the structural defects introduced when using metamorphic buffers. Here we present results on the fabrication and performance of four-junction mechanical stacks composed of GaInP/GaAs and GaInAsP/GaInAs tandems, grown on GaAs and InP substrates, respectively. The two tandems were bonded together with a low-index, transparent epoxy that acts as an omni-directional reflector to the GaAs bandedge luminescence, while simultaneously transmitting nearly all of the sub-bandgap light. As determined by electroluminescence measurements and optical modeling, the GaAs subcell demonstrates a higher internal radiative limit and thus higher subcell voltage, compared with GaAs subcells without enhanced internal optics; all four subcells exhibit excellent material quality. The device was fabricated with four contact terminals so that each tandem can be operated at its maximum power point, which raises the cumulative efficiency and decreases spectral sensitivity. Efficiencies exceeding 38% at one-sun have been demonstrated. Eliminating the series resistance is the key challenge for the concentrator cells. We will discuss the performance of one-sun and concentrator versions of the device, and compare the results to recently fabricated monolithic four-junction cells.

Original languageEnglish (US)
Title of host publication2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Print)9781479979448
DOIs
StatePublished - Dec 14 2015
Externally publishedYes
Event42nd IEEE Photovoltaic Specialist Conference, PVSC 2015 - New Orleans, United States
Duration: Jun 14 2015Jun 19 2015

Other

Other42nd IEEE Photovoltaic Specialist Conference, PVSC 2015
CountryUnited States
CityNew Orleans
Period6/14/156/19/15

    Fingerprint

Keywords

  • III-V solar cell
  • Mechanical stack
  • Multijunction solar cell
  • Photon recycling

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials

Cite this

Steiner, M. A., Geisz, J. F., Ward, J. S., Garcia, I., Friedman, D. J., King, R., Chiu, P. T., France, R. M., Duda, A., Olavarria, W. J., Young, M., & Kurtz, S. R. (2015). Mechanically stacked four-junction concentrator solar cells. In 2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015 [7356151] Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/PVSC.2015.7356151