Laboratory of semiconducting and photoactive "post-graphene" 2D materials, nanomaterials and nanocomposites

波长在400纳米到700纳米之间的可见光是光学科学的核心，因为它很容易以多种不同的方式产生、反射、传输和检测。实际上，日常生活中可用的任何可见光光学仪器都利用辐射，这种辐射在产生它的光源的尺寸上传播很远。不幸的是，这种“远场”光学在分辨非常小的物体的能力上受到衍射的固有限制，其分辨能力不低于波长。这表明远场可见光不适合用于纳米材料、量子点和二维（2D）材料的精确分析，其中1-100纳米以下的空间约束至关重要，并且在新物理和设备方面具有独特突破的潜力。限制效应至关重要的新设备包括：使能量转换更清洁的先进太阳能电池，使大数据社会更简单的数字存储设备，清洁环境的纳米多孔滤水器，以及延长便携式电子产品寿命的散热器。我们已经获得了在内部制造许多这些设备的技能，并且作为一个物理学家团队，我们正在使用概念验证设备原型来更好地了解纳入其中的特定材料的性能。我们研究的最基本方面集中在利用纳米光源附近产生的“近场”可见辐射来克服衍射，探测纳米尺度上的光-物质相互作用，并精确推断特定二维材料、纳米材料和纳米复合材料的性质。我们在孔径型扫描近场光学显微镜（SNOM）方面拥有独特的专业知识，这是一种近场技术，其中原子力显微镜（AFM）悬臂梁上钻入亚波长孔径，用于产生局部近场辐射，并扫描靠近该源的样品。因此，迄今为止仅在远场实施的许多光学技术将扩展到近场。石墨烯是一种完全由碳原子形成的二维材料，它的发现激发了人们对沿z轴约束的平面材料潜力的巨大兴趣，但下一代“后石墨烯”二维材料仍在等待最合适的工具来分析、操纵和整合到概念验证设备中，以高精度地了解其光学特性。在这里，特别强调将放在那些2D材料，纳米材料和纳米复合材料，不同于石墨烯，表现出半导体和光活性，如碳量子点，气凝胶，和2D过渡金属氧化物和硫族化合物。能够分析这些系统的SNOM工具是令人兴奋和理想的，可以培养下一代纳米光学和纳米物理领域多样化、包容性和高素质的人才。

Visible light, with wavelength between 400 nm and 700 nm, is at the core of optical sciences because it is simple to generate, reflect, transmit and detect it in so many different ways. Virtually any visible-light optical instrument available in everyday's life utilizes radiation that propagates at large distances over the size of the source that generates it. Unfortunately, this "far-field" optics is inherently limited by diffraction in the ability to resolve very small objects, with a resolving power no much less than a wavelength. This indicates that visible light in the far-field is unsuitable for the precise analysis of nanomaterials, quantum dots, and two-dimensional (2D) materials, in which spatial confinement below 1-100 nm is critical and has the potential of unique breakthroughs in terms of new physics and devices. Examples of new devices in which confinement effects are vital include: advanced solar cells that will make energy conversion cleaner, digital memory devices to make our big-data society simpler, nanoporous water filters to clean our environment, and heat spreaders to improve the lifetime of our portable electronics. We have acquired the skills to fabricate many of these devices in-house and, as a team of physicists, we are using proof-of-concept device prototypes to better understand the performance of specific materials incorporated into them. The most fundamental aspects of our research focus on the use of "near-field" visible radiation generated in the proximity of a nano-optical source to overcome diffraction, probe light-matter interaction at the nanoscale, and precisely infer the properties of specific 2D materials, nanomaterials and nanocomposites. We have unique expertise in aperture-type scanning near-field optical microscopy (SNOM) a near-field technique in which atomic force microscopy (AFM) cantilevers with sub-wavelength apertures drilled into them are used to generate localized near-field radiation and scan a sample in the close proximity of this source. Many optical techniques so far implemented only in the far-field will thus be extended to the near-field. The discovery of graphene, a 2D material entirely formed by carbon atoms, has spurred tremendous interest towards the potential of flat materials with confinement along the z-axis, but the next-generation of "post-graphene" 2D materials is still awaiting the most appropriate tools to be analyzed, manipulated and incorporated into proof-of-concept devices to understand their optical properties with high precision. Here, special emphasis will be placed on those 2D materials, nanomaterials and nanocomposites that, differently from graphene, exhibit semiconducting and photoactive properties, such as carbon quantum dots, aerogels, and 2D transition metal oxides and chalcogenides. SNOM tools capable of analyzing these systems are exciting and ideal to train the next-generation of diverse, inclusive and highly-qualified personnel in nano-optics and nano-physics.