Power generation from a radiative thermal source using a large-area infrared rectenna

TL;DR

This paper demonstrates direct electrical power generation from a thermal infrared source using a large-area nanoantenna-coupled tunnel diode rectifier, achieving measurable power density through photon-assisted tunneling.

Contribution

It introduces a large-area, unbiased infrared rectenna for thermal energy harvesting, with experimental validation and modeling of photon-assisted tunneling as the power conversion mechanism.

Findings

Power density of 8 nW/cm² at 450°C source temperature

Optimal load resistance matches tunnel diode impedance

Photon-assisted tunneling enables rectification without bias

Abstract

Electrical power generation from a moderate temperature thermal source by means of direct conversion of infrared radiation is important and highly desirable for energy harvesting from waste heat and micropower applications. Here, we demonstrate direct rectified power generation from an unbiased large-area nanoantenna-coupled tunnel diode rectifier, called a rectenna. Using a vacuum radiometric measurement technique with irradiation from a temperature-stabilized thermal source, a generated power density of 8 nW/cm$^2$ is observed at a source temperature of 450C for the unbiased rectenna across an optimized load resistance. The optimized load resistance for the peak power generation for each temperature coincides with the tunnel diode resistance at zero bias and corresponds to the impedance matching condition for a rectifying antenna. Current voltage measurements of a thermally illuminated large-area rectenna show current zero crossing shifts into the second quadrant indicating rectification. Photon-assisted tunneling in the unbiased rectenna is modeled as the mechanism for the large short-circuit photocurrents observed where the photon energy serves as an effective bias across the tunnel junction. The measured current and voltage across the load resistor as a function of the thermal source temperature represents direct current electrical power generation.