an9b01774_si_002.mp4 (17.09 MB)
Roll-to-Roll Deposition of Semiconducting 2D Nanoflake Films of Transition Metal Dichalcogenides for Optoelectronic Applications
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posted on 2019-11-17, 16:03 authored by Rebekah
A. Wells, Hannah Johnson, Charles R. Lhermitte, Sachin Kinge, Kevin SivulaExfoliated
transition metal dichalcogenide (TMD) nanomaterials
possess remarkable and tunable semiconducting properties which make
them competitive for use in ultrathin, flexible devices such as photodetectors,
sensors, and photoelectrodes for solar energy conversion. Until now,
the large-scale production of such devices has presented a challenge
that limits their commercialization and broad application. We demonstrate
here, for the first time, a procedure for the roll-to-roll (R2R) deposition
of two-dimensional (2D) TMD nanoflake thin films via a continuous
liquid–liquid interfacial self-assembly method. Remarkably,
no solvent removal is required during film deposition, nor is there
any nanoflake accumulation in the solvent bath, making continuous
operation feasible. In our prototype deposition system described herein,
TMD nanoflakes (9 nm average flake thickness, 50–500 nm long)
are self-assembled into large area films up to 100 mm in width that
are reproducibly printed at 10 mm s–1 with nanoflake
loadings of 35 mg m–2. Optically uniform coverage
on transparent conductive oxide-coated flexible plastic substrates
is shown, and key printing parameters to afford the required single-flake-layer
deposition are identified. Photoelectrochemical testing verifies optoelectronic
activity of the MoS2 nanoflake films achieving photocurrent
densities for iodide oxidation of 40 μA cm–2 at +0.1 V (vs an Ag/Ag+ reference) under 1 sun illumination.
In addition, we show that these R2R films are robust and that our
method works for multiple (successive) flake layer depositions by
preparing large area MoS2/WSe2 heterojunction
nanoflake films. This demonstration represents an important milestone
in advancing large-scale production of 2D TMD films toward low-cost,
high-performance optoelectronic devices.
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TMD nanoflake10 mm100 mm40 μenergy conversionPhotoelectrochemical testing verifies optoelectronic activityflake thicknessSemiconducting 2 D Nanoflake Filmsphotocurrent densitiesR 2R depositionconductive oxide-coated1 sun illuminationOptically uniform coverageTransition Metal Dichalcogenides2 D TMD filmsarea filmsflake layer depositionsRoll-to-Roll Depositiontunable semiconducting propertiesnanoflake loadingsnanoflake accumulationprinting parameterssingle-flake-layer depositionprototype deposition systemMoS 2 nanoflake filmsiodide oxidationfilm depositionplastic substratesR 2R filmsOptoelectronic Applications Exfoliated transition metal dichalcogenidemethod worksself-assembly methodoptoelectronic devices
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