A Noble-Transition Alloy Excels at Hot-Carrier Generation in the Near Infrared.

Stofela, Sara K F; Kizilkaya, Orhan; Diroll, Benjamin T; Leite, Tiago R; Taheri, Mohammad M; Willis, Daniel E; Baxter, Jason B; Shelton, William A et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

Above-equilibrium "hot"-carrier generation in metals is a promising route to convert photons into electrical charge for efficient near-infrared optoelectronics. However, metals that offer both hot-carrier generation in the near-infrared and sufficient carrier lifetimes remain elusive. Alloys can offer emergent properties and new design strategies compared to pure metals. Here, it is shown that a noble-transition alloy, Au<sub>x</sub> Pd<sub>1-</sub> <sub>x</sub> , outperforms its constituent metals concerning generation and lifetime of hot carriers when excited in the near-infrared. At optical fiber wavelengths (e.g., 1550 nm), Au<sub>50</sub> Pd<sub>50</sub> provides a 20-fold increase in the number of ≈0.8 eV hot holes, compared to Au, and a threefold increase in the carrier lifetime, compared to Pd. The discovery that noble-transition alloys can excel at hot-carrier generation reveals a new material platform for near-infrared optoelectronic devices.