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Nanoparticle-Based Photoelectrode Can Harvest 85% of Visible Light

posted by Fnord666 on Tuesday September 11 2018, @10:14PM   Printer-friendly
from the let-there-be-light-energy dept.

takyon writes:

Golden sandwich could make the world more sustainable

Scientists have developed a photoelectrode that can harvest 85 percent of visible light in a 30 nanometers-thin semiconductor layer between gold layers, converting light energy 11 times more efficiently than previous methods.

[...] In the study published in Nature Nanotechnology, the research team sandwiched a semiconductor, a 30-nanometer titanium dioxide thin-film, between a 100-nanometer gold film and gold nanoparticles to enhance light absorption. When the system is irradiated by light from the gold nanoparticle side, the gold film worked as a mirror, trapping the light in a cavity between two gold layers and helping the nanoparticles absorb more light.

To their surprise, more than 85 percent of all visible light was harvested by the photoelectrode, which was far more efficient than previous methods. Gold nanoparticles are known to exhibit a phenomenon called localized plasmon resonance which absorbs a certain wavelength of light. "Our photoelectrode successfully created a new condition in which plasmon and visible light trapped in the titanium oxide layer strongly interact, allowing light with a broad range of wavelengths to be absorbed by gold nanoparticles," says Hiroaki Misawa.

Enhanced water splitting under modal strong coupling conditions (DOI: 10.1038/s41565-018-0208-x) (DX)

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  • (Score: 1) by khallow on Wednesday September 12 2018, @12:44AM (3 children)

    by khallow (3766) Subscriber Badge on Wednesday September 12 2018, @12:44AM (#733419) Journal

    Scientists have developed a photoelectrode that can harvest 85 percent of visible light in a 30 nanometers-thin semiconductor layer between gold layers, converting light energy 11 times more efficiently than previous methods.

    Sounds exciting until you realize that only 40% of the energy of sunlight is in the visible light spectrum. In other words, they're claiming an efficiency of 34% which is considerably better, but not 11 times better than commercial solar cells (even at 85% across the entire spectrum, it wouldn't be 11 times better!). Presumably it'll capture some parts of the solar spectrum outside that range, but that is a deceptive claim.

  • (Score: 3, Informative) by khallow on Wednesday September 12 2018, @12:45AM

    by khallow (3766) Subscriber Badge on Wednesday September 12 2018, @12:45AM (#733420) Journal
    Link [tennessee.edu] to spectrum energy breakdown:

    At ground level, this decreases to about 1120-1000 watts/m2, and consists of 44% visible light, 3% ultraviolet (with the Sun at the zenith (directly overhead), but less at other angles), and the remainder infrared.

    Oops. 44% instead of 40% means about 37% efficiency.

  • (Score: 1, Interesting) by Anonymous Coward on Wednesday September 12 2018, @02:31PM (1 child)

    by Anonymous Coward on Wednesday September 12 2018, @02:31PM (#733607)

    Do you know that the efficiency for non-visible light is zero? Gold is also reflective at longer wavelengths. 11x refers to the earlier work with gold nan-particles.

    • (Score: 1) by khallow on Thursday September 13 2018, @01:13AM

      by khallow (3766) Subscriber Badge on Thursday September 13 2018, @01:13AM (#733943) Journal
      "Presumably it'll capture some parts of the solar spectrum outside that range"