Making More Responsive Photodetectors with Graphene

It seems like as soon as one new property of the wonder material graphene has been announced and explored; scientists discover a brand new one that once again dramatically increases its value to mankind, and expands its commercial use.

A very recent paper reported in Nature Nanotechnology, describes how a team of researchers at the University of Manchester led by Marcelo Lozada-Hidalgo have developed a graphene device which can increase the responsiveness of photodetectors 100,000 times higher than those on the commercial market today.

Experiments with Photosensitivity

The device itself is relatively simple, consisting of just a single layer of graphene enhanced with platinum nanoparticles. It was created for a research project that had the aim of determining whether or not a light beam could be effective in triggering proton transport through graphene, if the substance included additional light-sensitive materials. A beam of light was fired at the graphene and the photons then excited the graphene's electrons in the area of the platinum nanoparticles, sensitizing the electrons to protons.

An outcome that wasn't expected from the testing, was the indication that the graphene exhibited an enormous response by itself, without any of the additional materials being added. The technique isn't worlds apart from current methods used in semiconductor photodetectors, albeit with one key difference – it relies on proton transport, rather than electron transport. This is exciting to researchers as it could lead to the development of novel forms of photodetector architectures, which may result in brand new capabilities.

Graphene vs. Commercial Photodetectors

The metrics which assess photodetector performance are the following:

  • response time
  • photoresponsivity
  • noise equivalent power

In comparison to today’s commercial photodetectors, the graphene device is competitive in performance in these three criteria. Response time is around the same with the commercially available devices today, but it is expected to exceed this with work. Noise equivalent power is also similar or slightly better in the graphene-based photodetectors.

The most striking difference in performance though, is in the area of photoresponsivity, with the graphene device showing a 100,000 times increase in photoresponsivity compared to the market versions today.

The UoM research team also notes that the experiment was never looking to optimize these characteristics, leaving plenty of room for future enhancements. If the original plan of adding additional photosensitive materials, such as quantum dots, was put into practice, the photoresponsivity could go off the charts.

Other Applications for Graphene

Along with the incredible new use graphene detailed above, this miracle substance has already been included in patents for at least 15,000 other products or applications. These uses range from smartphone displays, stretchable electronics, advanced solar cells, to medical devices, sensors, batteries, and water desalination membranes.

The most advanced method for production of the highest quality graphene is through a process called chemical vapor deposition (CVD), and this CVD graphene is the expertise of the highly respected manufacturer, Grolltex.  

At one atom thick, graphene sheets are one million times thinner than a sheet of paper, and for all intents and purposes can be considered to be two-dimensional. However, they are 200 times stronger than steel, due to their structure of interlocking carbon latticework. Its electrical conductivity is among the highest known to man, and yet is an incredibly strong natural barrier.

It is still a relatively new material, as the properties it exhibits have only been explored since 2004, when it was ‘rediscovered’ by scientists at the University of Manchester. Undoubtedly, there are even greater discoveries to come, and even more uses will be found for it.

This information has been sourced, reviewed and adapted from materials provided by Grolltex.

For more information on this source, please visit Grolltex.

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