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

自2004年首次演示通过剥离块状石墨的透明胶带来制造石墨烯以来，2D材料的制造方法取得了惊人的进步。今天，有几种主要的合成方法，每种方法都有其明显的优缺点。液相剥离(LPE)是一种低成本、可扩展的方法，已被证明能有效地将大量材料剥离成其2D对应的胶体分散体。剥离后，溶剂屏蔽2D材料的片间吸引力，以保持各层之间的距离。LPE是制备基于2D材料的油墨、薄膜和复合材料的理想方法。在电磁光谱的中红外(MIR)区域有大量与LPE兼容的有趣的光吸收材料，如石墨烯、二硒化钛(TiSe2)、黑磷和铋。这些材料的拉曼光谱、透射电子光谱和电子衍射表明，所得到的薄膜由随机排列的2D薄片组成，保持了只能归因于材料的二维性质的性质。在肯尼迪实验室和曼纳德博士在渥太华大学的研究小组合作的这个项目中，我们计划制造用于中红外区域光学传感应用的LPE 2D材料。我们将使用已建立的制造和提纯工艺，并测试不同的沉积技术，如滴注和喷涂，这在制造大型2D材料器件方面具有巨大的潜力。在薄膜上沉积金电极将允许表征其电学性质，并提供检测入射MIR光的接口。光学表征装置将用于测试探测器的响应度、光谱带宽、线性度和上升时间。在未来，我们的研究可能会导致大表面MIR探测器的发展，这种探测器可以叠加到硅基太阳能电池上，以提高整体的光伏效率。

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.