Integrated near-field thermo-photovoltaics for heat recycling.

Bhatt, Gaurang R; Zhao, Bo; Roberts, Samantha; Datta, Ipshita; Mohanty, Aseema; Lin, Tong; Hartmann, Jean-Michel; St-Gelais, Raphael et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Energy transferred via thermal radiation between two surfaces separated by nanometer distances can be much larger than the blackbody limit. However, realizing a scalable platform that utilizes this near-field energy exchange mechanism to generate electricity remains a challenge. Here, we present a fully integrated, reconfigurable and scalable platform operating in the near-field regime that performs controlled heat extraction and energy recycling. Our platform relies on an integrated nano-electromechanical system that enables precise positioning of a thermal emitter within nanometer distances from a room-temperature germanium photodetector to form a thermo-photovoltaic cell. We demonstrate over an order of magnitude enhancement of power generation (P<sub>gen</sub> ~ 1.25 μWcm<sup>-2</sup>) in our thermo-photovoltaic cell by actively tuning the gap between a hot-emitter (T<sub>E</sub> ~ 880 K) and the cold photodetector (T<sub>D</sub> ~ 300 K) from ~ 500 nm down to ~ 100 nm. Our nano-electromechanical system consumes negligible tuning power (P<sub>gen</sub>/P<sub>NEMS</sub> ~ 10<sup>4</sup>) and relies on scalable silicon-based process technologies.