Harvesting Sub-Bandgap IR Photons by Photothermionic Hot Electron Transfer in a Plasmonic p-n Junction.
basic_science · Level V
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- Record sourced from PubMed, PMID 33877837.
- Also identified by DOI 10.1021/acs.nanolett.1c00932.
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Abstract
Plasmonic semiconductors are an emerging class of low-cost plasmonic materials, and the presence of a bandgap and band-bending in these materials offer new opportunities to overcome some of the limitations of plasmonic metals. Here, we demonstrate that in a plasmonic p-n heterojunction (Cu<sub>2-x</sub>Se-CdSe) the near-IR excitation (1.1 eV) of the hole plasmon in the p-Cu<sub>2-<i>x</i></sub>Se phase results in rapid hot electron transfer to n-CdSe, with an energy 2.2 eV above the Fermi level. This hot electron generation and energy upconversion process can be well-described by a photothermionic mechanism, where the presence of a bandgap in p-Cu<sub>2-<i>x</i></sub>Se facilitates the generation of energetic photothermal electrons. The lifetime of the transferred electrons in Cu<sub>2-<i>x</i></sub>Se-CdSe can reach ∼130 ps, which is nearly 100× longer than that of its metal-semiconductor counterpart. This result demonstrates a novel approach for harvesting the sub-bandgap near IR photons using plasmonic p-n junctions and the potential advantages of plasmonic semiconductors for hot carrier-based devices.