Browsing by Author "Bonaccorso, Francesco"

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Liquid Phase Exfoliated Indium Selenide Based Highly Sensitive Photodetectors
(Wiley-V C H Verlag Gmbh, 2020) Curreli, Nicola; Serri, Michele; Spirito, Davide; Lago, Emanuele; Petroni, Elisa; Martin-Garcia, Beatriz; Bonaccorso, Francesco
Layered semiconductors of the IIIA-VIA group have attracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their thickness-dependent optical and electronic properties, which promise ultrafast response and high sensitivity. In particular, 2D indium selenide (InSe) has emerged as a promising candidate for the realization of thin-film field effect transistors and phototransistors due to its high intrinsic mobility (>10(2) cm(2) V-1 s(-1)) and the direct optical transitions in an energy range suitable for visible and near-infrared light detection. A key requirement for the exploitation of large-scale (opto)electronic applications relies on the development of low-cost and industrially relevant 2D material production processes, such as liquid phase exfoliation, combined with the availability of high-throughput device fabrication methods. Here, a beta polymorph of indium selenide (beta-InSe) is exfoliated in isopropanol and spray-coated InSe-based photodetectors are demonstrated, exhibiting high responsivity to visible light (maximum value of 274 A W-1 under blue excitation 455 nm) and fast response time (15 ms). The devices show a gate-dependent conduction with an n-channel transistor behavior. Overall, this study establishes that liquid phase exfoliated beta-InSe is a valid candidate for printed high-performance photodetectors, which is critical for the development of industrial-scale 2D material-based optoelectronic devices.
Liquid-Phase Exfoliated Indium-Selenide Flakes and Their Application in Hydrogen Evolution Reaction
(Wiley-VCH Verlag GmbH, 2018) Petroni, Elisa; Lago, Emanuele; Bellani, Sebastiano; Boukhvalov, Danil W.; Politano, Antonio; Gurbulak, Bekir; Bonaccorso, Francesco
Single- and few-layered InSe flakes are produced by the liquid-phase exfoliation of -InSe single crystals in 2-propanol, obtaining stable dispersions with a concentration as high as 0.11 g L-1. Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as-produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at approximate to 5 nm, corresponding to 4 Se-In-In-Se quaternary layers. It is also shown that no formation of further InSe-based compounds (such as In2Se3) or oxides occurs during the exfoliation process. The potential of these exfoliated-InSe few-layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single-walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes.