MXenes for Plasmonic Photodetection.
basic_science · Level V
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- Record sourced from PubMed, PMID 31222823.
- Also identified by DOI 10.1002/adma.201807658.
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Abstract
MXenes have recently shown impressive optical and plasmonic properties associated with their ultrathin-atomic-layer structure. However, their potential use in photonic and plasmonic devices has been only marginally explored. Photodetectors made of five different MXenes are fabricated, among which molybdenum carbide MXene (Mo<sub>2</sub> CT<sub>x</sub> ) exhibits the best performance. Mo<sub>2</sub> CT<sub>x</sub> MXene thin films deposited on paper substrates exhibit broad photoresponse in the range of 400-800 nm with high responsivity (up to 9 A W<sup>-1</sup> ), detectivity (≈5 × 10<sup>11</sup> Jones), and reliable photoswitching characteristics at a wavelength of 660 nm. Spatially resolved electron energy-loss spectroscopy and ultrafast femtosecond transient absorption spectroscopy of the MXene nanosheets reveal that the photoresponse of Mo<sub>2</sub> CT<sub>x</sub> is strongly dependent on its surface plasmon-assisted hot carriers. Additionally, Mo<sub>2</sub> CT<sub>x</sub> thin-film devices are shown to be relatively stable under ambient conditions, continuous illumination and mechanical stresses, illustrating their durable photodetection operation in the visible spectral range. Micro-Raman spectroscopy conducted on bare Mo<sub>2</sub> CT<sub>x</sub> film and on gold electrodes allowing for surface-enhanced Raman scattering demonstrates surface chemistry and a specific low-frequency band that is related to the vibrational modes of the single nanosheets. The specific ability to detect and excite individual surface plasmon modes provides a viable platform for various MXene-based optoelectronic applications.