Nanolaminate coatings of liquid exfoliated 2D materials for mid-infrared optical sensors

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Methods for the fabrication of 2D materials have advanced at an extraordinary pace since the first demonstration of graphene fabrication by peeling Scotch tape off bulk graphite in 2004. Today, there are several main methods of synthesis, each with their own distinct advantages and disadvantages. Liquid Phase Exfoliation (LPE) is a low-cost and scalable method that has proven effective at exfoliating bulk materials into colloidal dispersions of their 2D counterparts. After exfoliation, the solvent screens inter-sheet attractive forces of the 2D material to keep layers apart. LPE is an ideal method for fabricating 2D materials-based inks, thin films and composites. There is a wide range of interesting materials with a large optical absorption in the Mid-Infrared (MIR) region of the electromagnetic spectrum that are LPE compatible such as graphene, titanium diselenide (TiSe2), black phosphorous and bismuth. Raman spectroscopy, transmission electron spectroscopy and electron diffraction of these materials have demonstrated that the resulting films, composed of a randomized arrangement of 2D flakes, maintain properties that can only be attributed to the bi-dimensional nature of the material. In this collaborative project between Kennedy Labs and Dr. Ménard's research group at uOttawa, we propose to fabricate LPE 2D materials for optical sensing application in the mid-infrared region. We will use an established fabrication and purification process and test different deposition techniques such as drop casting and spray coating, which has a great potential for fabricating large 2D materials devices. Deposition of gold electrodes onto the thin films will allow the characterization of their electrical properties as well as provide an interface to detect incident MIR light. An optical characterization setup will be used to test the responsivity, spectral bandwidth, linearity and rise time of the detectors. In the future, our research could lead to the development of large-surface MIR detectors, which could be super-imposed to Si-based solar cells to enhance the overall photovoltaic efficiency.