Carbon nanorods open door to multispectral light sensors

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Ultrahigh Performance C60 Nanorod Large Area Flexible Photoconductor Devices via Ultralow Organic and Inorganic Photodoping - .PDF file.

A new multispectral light sensor that detects light from the ultra-violet through the to visible and into the near infrared light has been developed at Surrey University.

The new development overcomes issues associated with bulk crystalline semiconductors used for near infrared (NIR) applications, which are expensive to make, have limited spectral range and difficult to keep pure, using relatively low-cost organic materials and semiconductor nanocrystals to access the visual wide spectral range.

In use, the new light sensor – which exploits the properties of one dimensional single-crystal nanorods of C60 – could be used in medical and security imaging via low cost cameras, pairing low cost NIR imaging with conventional imaging.

Dr Richard Curry, from Surrey’s Advanced Technology Institute said the sensor – which separates out the role of absorbing photons and carrying the current flow into two separate parts – works from the UV through to about 1,400nm, which is out towards where telecommunications is used in the NIR.

‘It has something called a large linear dynamic range, which means you get a linear response for a wide range of light levels right from nanoWatts/cm squared right up to mW,’ he said. ‘That linearity is also very useful, there’s no saturation effects going on in this detector.

‘The thing that surprised us most is that one of the performance characteristics – called detectivity, this figure of merit for these detectors – is better than a lot of the commercially existing detectors in the NIR and it matches most of those in the visible as well.

‘So now we have a detector that can do sensing across the entire range rather than having to buy two or three detectors and packaging them together in an expensive system.’

The team will now focus on targeting NIR applications – plus more robust packaging – for the sensors, which are flexible, can be produced inexpensively and do not require specialised manufacturing conditions.

A paper detailing the development has been published in Nature’s Scientific Reports. Click here to read more.