Solution-processed graphene–nanographene van der Waals heterostructures for photodetectors with efficient and ultralong charge separation
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.
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)