Comparison of bolometer type room temperature photodetectors, based on MWCNTs, combined with tobacco cells or embedded in a polymer matrix

Bolometer type photodetectors with a high sensitivity in a wide range of wavelengths, ranging from the ultraviolet throughout the visible and up to the near infrared, have been fabricated utilizing the same type of multi-walled carbon nanotubes, but different matrices: in the first case a biological matrix based on tobacco cells has been used and in the second case high density polyethylene, a conventional polymer. The two investigated nanocomposite materials showed very different temperature coefficients, but both a clear negative temperature coefficient type behavior. It has been found that, despite the very different sample conductivities, both nanocomposites can be operated as photodetectors at room temperature. For the polyethylene based nanocomposite device, random-telegraph-noise has been found to limit the bolometer operation. Instead, for the tobacco cell based nanocomposite bolometer, the high sensitivity of the dark current to ambient temperatures leads to baseline fluctuations, but the photocurrent amplitude remains almost unaffected and a good signal-to-noise ratio has been obtained also for low light intensities.