Nano-scale heat transfer

https://www.nature.com/articles/s41467-020-16197-6

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_gen ~ 1.25 μWcm⁻²) in our thermo-photovoltaic cell by actively tuning the gap between a hot-emitter (T_E ~ 880 K) and the cold photodetector (T_D ~ 300 K) from ~ 500 nm down to ~ 100 nm. Our nano-electromechanical system consumes negligible tuning power (P_gen/P_NEMS ~ 10⁴) and relies on scalable silicon-based process technologies.

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