Large variations in both dark- and photoconductivity in nanosheet networks as nanomaterial is varied from MoS2 to WTe2. Issue 1 (18th November 2014)

• Record Type: Journal Article
• Authors: Cunningham, Graeme; Hanlon, Damien; McEvoy, Niall; Duesberg, Georg S.; Coleman, Jonathan N.
• Is Part Of: Nanoscale. Volume 7:Issue 1(2015)
• Page Start: 198
• Page End: 208
• Publication Date: 2014-11-18
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c4nr04951a
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : We observe large variations in both dark- and photoconductivity of solution-processed networks of different transition metal chalcogenides. 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.