Growth Engineering of Plasmonic Nanostructures with ALD

太阳能是国家战略的一个重要组成部分，该战略旨在使我国经济摆脱化石燃料，以应对二氧化碳排放和气候变化。太阳光由不同波长的电磁能组成，主要范围从紫外线到红外线，可见光介于两者之间。基于硅和其他半导体的当前光伏（PV）太阳能电池技术由于其固有的电特性而仅捕获来自太阳的电磁能量的一部分。太阳光的部分收集和使用限制了它们的效率和可以从给定的太阳能电池区域产生的功率的量，最普通的硅PV电池具有32%的绝对效率上限。光具有光子和电磁波的特性，用天线制成的新型太阳能电池收集太阳光的电磁波是有好处的。纳米级天线比PV材料更灵活，并且可以用于收集当前半导体PV电池不能转换为电流的太阳光谱的部分。在这个研究项目中，将研究纳米天线阵列的特性，以及能够控制原子水平的纳米纤维技术，以促进对新材料如何帮助收集太阳能的理解。该项目还将支持招聘和教育多元化的STEM劳动力。本研究计划将由工程系本科生与研究生共同参与，并提出一项实验研究计画，以探讨电浆纳米结构在能源应用上的制程工程。等离子体激元材料在电致伸缩、化学传感器、电光学和能量产生中具有越来越多的应用。等离子体纳米结构由于强烈增强的激发局部表面等离子体共振（LSPR）的光-物质相互作用而对于收集太阳能特别感兴趣。纳米结构可以被设计成使得等离子体共振直接与太阳光谱重叠，包括UV、可见光和近红外（NIR）区域，这使得它们非常适合于太阳能收集，克服了半导体PV电池的带隙限制性质。等离子体激元的新应用之一是用光频天线收集光。等离子体天线是将电磁（EM）能量转换成电流和电压的纳米结构。它们可以通过收集太阳光谱中未使用的近红外区域来增强太阳能技术，以提高整体效率。为了有效地收集太阳光，等离子体天线必须具有纳米尺度的特征（隧道结），这是目前纳米制造方法无法产生的。因此，有人提出，区域选择性原子层沉积（AS-ALD）将与纳米纤维相结合，以创建天线结的互连阵列。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Solar energy is a critical component of the national strategy to transition our economy away from fossil fuels to combat carbon dioxide emissions and climate change. Sunlight is composed of different wavelengths of electromagnetic energy that primarily range from ultraviolet to infrared, with visible light in between. Current photovoltaic (PV) solar cell technologies based on silicon and other semiconductors capture only a portion of the electromagnetic energy from the sun due to their intrinsic electrical properties. The partial collection and use of sunlight limits their efficiency and the amount of power that can be generated from a given solar cell area, e.g., the most common silicon PV cell has an absolute upper efficiency limit of 32%. Light has properties of both photons and electromagnetic waves and there are advantages to harvesting sunlight’s electromagnetic waves with new types of solar cells made with antennas. Nanoscale antennas are more flexible than PV materials and may be useful to collect the portion of the solar spectrum that current semiconductor PV cells are incapable of converting to electrical current. In this research project, the properties of nanoscale antenna arrays, together with nanofabrication techniques capable of atomistic levels of control, will be studied to advance understanding of how new materials may help harvest solar energy. The project also will support the recruitment and education of a diverse STEM workforce. Both undergraduate and graduate engineering students will participate in the research activities.An experimental research program is proposed to investigate process engineering of plasmonic nanostructures for energy applications. Plasmonic materials have a growing number of applications in photocatalysis, chemical sensors, electro-optics, and energy generation. Plasmonic nanostructures are especially interesting for collecting solar energy due to strongly enhanced light-matter interactions that excite localized surface plasmon resonances (LSPR). Nanostructures can be engineered so that plasmon resonances directly overlap the solar spectrum, including the UV, visible, and near-infrared (NIR) regions, which makes them highly suitable for solar energy harvesting, overcoming the band-gap-limited nature of semiconductor PV cells. One of the new applications for plasmonics is collecting light with optical frequency antennas. Plasmonic antennas are nanostructures that convert electromagnetic (EM) energy into electrical currents and voltages. They can enhance solar energy technology by collecting unused NIR regions of the solar spectrum to enhance overall efficiency. To collect sunlight efficiently, the plasmonic antennas must have nanoscale features (tunnel junctions) that are impossible to generate with current nanofabrication methods. Therefore, it is proposed that area-selective atomic layer deposition (AS-ALD) will be combined with nanofabrication to create the interconnected arrays of antenna junctions. Methods to reduce the temperature and the exposure times of current metal AS-ALD processes will be investigated.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.