title: Large variations in both dark- and photoconductivity in nanosheet networks as nanomaterial is varied from MoS2 to WTe2.
abstract: We have used solution processing techniques to fabricate thin-film networks of nanosheets of six different transition metal dichalcogenides; MoS2, MoSe2, MoTe2, WS2, WSe2 and WTe2. We have measured both the dark conductivity and the photoconductivity under broad band illumination in the intensity range from 0-1500 W m(-2). The dark conductivity varied from ∼ 10(-6) S m(-1) for MoS2 to ∼ 1 S m(-1) for WTe2, with an apparent exponential dependence on bandgap. All materials studied show photocurrents which rise slowly with time and depend sub-linearly on light intensity, both hallmarks of trap limited processes. Because the photoresponse depends relatively weakly on bandgap, the ratio of photo- to dark conductivity is largest for the sulphides because of their lower dark conductivities. As such, MoS2 and WS2 may be best suited to photo-detection applications. However, due to their lower bandgap and superior conductivity, WSe2 and WTe2 might prove more effective in other applications, for example in photovoltaic cells.
authors.affiliation: School of Physics, CRANN and AMBER Research Centres, Trinity College Dublin, University of Dublin, Dublin 2, Ireland.
authors.forename: Graeme
authors.initials: G
authors.lastname: Cunningham
authors.forename: Damien
authors.initials: D
authors.lastname: Hanlon
authors.forename: Niall
authors.initials: N
authors.lastname: McEvoy
authors.forename: Georg S
authors.initials: GS
authors.lastname: Duesberg
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Coleman