Strong coupling of plasmon and nanocavity modes for dual-band, near-perfect absorbers and ultrathin photovoltaics
2016 (English)In: ACS Photonics, ISSN 2186-2311, E-ISSN 2161-5063, Vol. 3, no 3, 456-463 p.Article in journal (Refereed) Published
When optical resonances interact strongly, hybridized modes are formed with mixed properties inherited from the basic modes. Strong coupling therefore tends to equalize properties such as damping and oscillator strength of the spectrally separate resonance modes. This effect is here shown to be very useful for the realization of near perfect dual-band absorption with ultrathin (~10 nm) layers in a simple geometry. Absorber layers are constructed by atomic layer deposition of the heavy-damping semiconductor tin monosulfide (SnS) onto a two-dimensional gold nanodot array. In combination with a thin (55 nm) SiO2 spacer layer and a highly reflective Al film on the back, a semi-open nanocavity is formed. The SnS coated array supports a localized surface plasmon resonance in the vicinity of the lowest order anti-symmetric Fabry-Perot resonance of the nanocavity. Very strong coupling of the two resonances is evident through anti-crossing behavior with a minimum peak splitting of 400 meV, amounting to 24% of the plasmon resonance energy. The mode equalization resulting from this strong interaction enables simultaneous optical impedance matching of the system at both resonances, and thereby two near perfect absorption peaks which together cover a broad spectral range. When paired with the heavy damping from SnS band-to-band transitions, this further enables approximately 60% of normal incident solar photons with energies exceeding the bandgap to be absorbed in the 10 nm SnS coating. Thereby, these results establish a distinct relevance of strong coupling phenomena to efficient, nanoscale photovoltaic absorbers and more generally for fulfilling a specific optical condition at multiple spectral positions.
Place, publisher, year, edition, pages
2016. Vol. 3, no 3, 456-463 p.
strong interaction, plasmonic solar cells, tin monosulfide, atomic layer deposition, localized surface plasmon resonances, vacuum Rabi splitting
Nano Technology Materials Engineering Condensed Matter Physics
Research subject Physics with spec. in Atomic, Molecular and Condensed Matter Physics; Engineering Science
IdentifiersURN: urn:nbn:se:uu:diva-280346DOI: 10.1021/acsphotonics.5b00651ISI: 000372479500022OAI: oai:DiVA.org:uu-280346DiVA: diva2:910631
FunderMarcus and Amalia Wallenberg Foundation