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Solution-processed graphene–nanographene van der Waals heterostructures for photodetectors with efficient and ultralong charge separation

Abstract : 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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https://hal-cea.archives-ouvertes.fr/cea-03374221
Contributor : Serge Palacin Connect in order to contact the contributor
Submitted on : Tuesday, October 12, 2021 - 7:52:56 AM
Last modification on : Friday, October 15, 2021 - 2:18:08 PM

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Zhaoyang Liu, Haixin Qiu, Shuai Fu, Can Wang, Xuelin Yao, et al.. Solution-processed graphene–nanographene van der Waals heterostructures for photodetectors with efficient and ultralong charge separation. Journal of the American Chemical Society, American Chemical Society, 2021, ⟨10.1021/jacs.1c07615⟩. ⟨cea-03374221⟩

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