PerspectivePhysics

Plasmons at the interface

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Science  07 Aug 2015:
Vol. 349, Issue 6248, pp. 587-588
DOI: 10.1126/science.aac8522

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Summary

Absorption of photons by solid materials is critical for applications such as photovoltaics (1), photocatalysis (2), and sensors (3). Fundamental to these technologies is the design of materials that can efficiently absorb photons of desired wavelengths and direct the separation and transport of the generated charge carriers [electrons (negative) and holes (positive)] to their respective collectors. Materials with high concentrations of free conducting electrons, such as coinage metals (Ag, Au, and Cu), have attracted attention for these applications because of their tunable ability to strongly concentrate a light flux in small volumes via the excitation of resonant surface plasmons. However, the lifetime of useful electrons and holes generated in metals upon the decay of surface plasmons is on the order of 1 ps, which limits their efficient collection. On page 632 of this issue, Wu et al. (4) overcome this limitation by demonstrating a direct, instantaneous transfer of plasmon-derived electrons into interfacial semiconductors that allows for efficient solar energy harvesting across a broad range of photon energies.