publication detail
Solution-processed graphene–nanographene van der Waals heterostructures for photodetectors with efficient and ultralong charge separation
AUTHORS
Document type
Journal articles
Résumé
Sensitization of graphene with inorganic semiconducting nanostructures has been demonstrated as a powerful strategy to boost its optoelectronic performance. However, the limited tunability of optical properties and toxicity of metal cations in the inorganic sensitizers prohibits their widespread applications, and the in-depth understanding of the essential interfacial charge-transfer process within such hybrid systems remains elusive. Here, we design and develop high-quality nanographene (NG) dispersions with a large-scale production using high-shear mixing exfoliation. The physisorption of these NG molecules onto graphene gives rise to the formation of graphene–NG van der Waals heterostructures (VDWHs), characterized by strong interlayer coupling through $\pi$–$\pi$ interactions. As a proof of concept, photodetectors fabricated on the basis of such VDWHs show ultrahigh responsivity up to 4.5 × 10$^7$ A/W and a specific detectivity reaching 4.6 × 10$^{13}$ Jones, being competitive with the highest values obtained for graphene-based photodetectors. The outstanding device characteristics are attributed to the efficient transfer of photogenerated holes from NGs to graphene and the long-lived charge separation at graphene–NG interfaces (beyond 1 ns), as elucidated by ultrafast terahertz (THz) spectroscopy. These results demonstrate the great potential of such graphene–NG VDWHs as prototypical building blocks for high-performance, low-toxicity optoelectronics.
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