Speaker
Description
Graphene's excellent optoelectronic properties have been exploited to achieve sensitive broadband photodetection via the hot-electron photothermoelectric effect. We propose that the same effect could be utilised for mid-infrared thermoradiative energy harvesting with high internal quantum efficiency in graphene.
As a step towards this goal, we have fabricated a high-quality graphene pn-junction on hexagonal boron nitride. We demonstrate a novel two-frequency technique to measure the thermopower response of our graphene pn-junctions: thermopower was measured by heating with alternating current (Joule heating) at frequency $\omega$ and the thermopower response probed at $2\omega$. The temperature response from Joule heating was modelled, and the thermopower was thereby inferred. Its dependence on carrier density showed good agreement with graphene transport theories, but a peak thermopower of around 24 μV/K was lower than previously reported for similar graphene devices. We seek to improve on this by using four terminal sensing to overcome contact resistance and by using a cryostat to vary the junction’s temperature.
I will discuss our latest work to create efficient graphene thermoelectric generators, and couple them to mid-infrared resonant nanostructures fabricated in silicon carbide to achieve mid-infrared thermoradiative devices for nighttime radiative energy harvesting.
| I am the presenting author | Yes |
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