New Publication: Toward efficient and tailorable mid-infrared emitters utilizing multilayer graphene

Dean Patient

Congratulations to fourth-year PGR Dean Patient, whose paper ‘Toward efficient and tailorable mid-infrared emitters utilizing multilayer graphene’ was recently published in Applied Physics Letters.

Dean summarises the paper’s findings:

In this work, we experimentally fabricate devices consisting of multi-layer graphene with an incorporated back-reflector. The resultant devices have a roughly 4-fold increase in emission compared to identical devices without the mirror. Such devices can no longer be modelled using a simple Blackbody model, and so we derive two analytic methods to understand how these devices work. The first describes the power output via. the fluctuation-dissipation theorem, and the second is a more simple approach, approximating the device as being `blackbody-like’, but allowing the greybody factor to be temperature and wavelength dependant. We find that both theories accurately model the devices, and fit well to the experimental data. We finally show that the efficiency of these devices are comparable to current LED architectures, demonstrating the feasibility of developing graphene-based mid-infared LEDs, which could be more cost effective and sustainable to manufacture.

Please read below for the paper’s abstract:


There is a continuing need for the development of cost-effective and sustainable mid-infrared light sources for applications such as gas sensing and infrared beacons. A natural replacement for the conventional incandescent sources still widely used in such applications is semiconductor LEDs, but to achieve emission at long wavelengths requires the realization of devices with narrow effective bandgaps, inherently leading to relatively poor internal and external quantum efficiencies. Recently, the technological potential of graphene-based incandescent emitters has been recognized, in part due to the ability of graphene to sustain extremely large current densities. Here, we introduce a simple architecture, consisting of a back-reflector behind a multilayer graphene filament, which we use to produce emitters with wall-plug-efficiencies comparable to state-of-the art semiconductor cascade LEDs. Coupled with the potential for high-speed modulation, resulting from the low thermal mass, our results demonstrate the feasibility of creating practicable infrared sources.
The authors would like to thank Dr. Cheng Shi and Dr. Isaac Luxmoore for useful discussions. This work was funded via an EPSRC Fellowship (G.R.N.) in Frontier Manufacturing (Grant No. EP/J018651/1), the EPSRC Prosperity Partnership “The Tailored Electromagnetic and Materials Accelerator” (Grant No. EP/R004781/1), which is a collaboration with QinetiQ Ltd., and via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1).

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