OP: COLLABORATIVE RESEARCH: Integrated Simulation of Non-homogeneous Thin-film Photovoltaic Devices

OP：协作研究：非均质薄膜光伏器件的集成模拟

• 批准号: 1619901
• 负责人: Akhlesh Lakhtakia
• 金额: $ 21万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1619901&HistoricalAwards=false
• 关键词: OP; COLLABORATIVE; RESEARCH; Integrated; Simulation

Solar cells are desirable as energy sources that neither use fossil fuels nor produce greenhouse gases. They must be designed to efficiently absorb sunlight and convert it to electricity. The solar cell needs to be sufficiently thick to absorb light across the solar spectrum. To reduce this thickness, and so reduce manufacturing cost, several layers of materials are used: first, to help light penetrate the solar cell, and then to trap it inside. Some of these layers are semiconductors in which electricity is generated, while others (for example, a periodically corrugated metallic back layer) may help absorption by trapping light near their surface. However, the amount of electricity generated by a solar cell does not just depend on absorption, but also on the transport of electrons within the layers of the solar cell. If the density of electrons decreases during transport, thereby trumping any gain in sunlight absorption, then a chosen light-management strategy will not be fruitful. The project team will develop an integrated pair of computer models that simultaneously predict the absorption of sunlight and the consequent electrical performance of the solar cell using modern techniques from numerical analysis. The codes will extend current simulation technology to allow for semiconductor layers with properties that vary from place to place and allow fully three-dimensional models of the device. Using their codes, the PIs will optimize device designs for best electricity generation. Definitive predictions will be provided about thin-film photovoltaic solar cells, thereby providing significant progress towards inexpensive and sustainable production of electricity. These codes will be made available to other photovoltaic researchers.The overall model of the thin-film photovoltaic solar cell will have a photonic submodel and an electrical submodel. In the photonic model, the quasi-periodic Maxwell's equations will be solved using edge finite elements. To improve flexibility, the PIs will analyze and implement a non-standard mortaring technique to take care of quasi-periodicity. Compatible electrical models will be analyzed and implemented using the Hybridizable Discontinuous Galerkin (HDG) method on hexahedral elements for the non-linear convection and diffusion problem governing drift and diffusion of electrical charge carriers. The HDG scheme will require a novel analysis to understand this non-linear convection-diffusion problem. Stability and convergence will be explored first for linear convection-diffusion problems, and the methodology will then be extended to an implicit-explicit time-stepping scheme for the drift-diffusion system. Besides a full 3D model, the PIs will develop a 2D model assuming translation invariance of the photovoltaic device in one transverse direction. The second step of the proposed research is to use the new simulation capability to design optimal nonhomogeneous thin-film photovoltaic solar cells via the Differential Evolution Algorithm. This will optimize for maximal photovoltaic electricity-generation efficiency. Additionally, domain and coefficient derivatives will be characterized and implemented to allow the computation of sensitivities and the use of gradient-based optimization. Detailed photonic-and-electrical modeling with doubly periodic back-reflectors and non-homogeneous light-absorbing layers will permit a major expansion of solar-cell design methodologies, besides yielding optimal designs for maximal photovoltaic electricity-generation efficiency.

太阳能电池是不使用化石燃料也不会产生温室气体的能源。它们必须旨在有效吸收阳光并将其转换为电能。太阳能电池需要足够厚，以吸收在太阳光谱中的光。为了减少这种厚度，并因此降低了制造成本，使用了几层材料：首先，为了帮助光穿透太阳能电池，然后将其捕获到其中。其中一些层是产生电力的半导体，而其他层（例如，定期瓦楞金属后层）可能通过捕获表面附近的光线来帮助吸收。但是，太阳能电池产生的电量不仅取决于吸收，还取决于在太阳能电池层中电子的传输。如果电子的密度在运输过程中降低，从而胜过吸收阳光的任何收益，那么选择的轻型管理策略将不会富有成果。该项目团队将开发一对集成的计算机模型，同时使用数值分析中的现代技术来预测阳光的吸收以及导致太阳能电池的电气性能。这些代码将扩展当前的仿真技术，以允许半导体层的特性各不相同，并允许设备的完全三维模型。使用其代码，PI将优化设备设计，以发电最佳。将对薄膜光伏太阳能电池提供确定的预测，从而为廉价且可持续的电力产生提供重大进展。这些代码将提供给其他光伏研究人员。薄膜光伏太阳能电池的整体模型将具有光子子模型和电s子模型。在光子模型中，准周期性麦克斯韦的方程将使用边缘有限元素求解。为了提高灵活性，PIS将分析和实施一种非标准的勇敢技术来照顾准周期性。将使用六面体元素上的杂交不连续的Galerkin（HDG）方法对兼容的电模型进行分析和实施，以进行非线性对流和延伸问题，控制漂移和电荷载体的扩散。 HDG方案将需要新的分析来了解这种非线性对流扩散问题。对于线性对流 - 扩散问题，将首先探索稳定性和收敛性，然后将方法扩展到漂移扩散系统的隐式解张时步骤方案。除了完整的3D模型外，PIS还将开发一个2D模型，假设光伏设备在一个横向方向上的平移不变。 拟议的研究的第二步是使用新的仿真能力来设计最佳的非均匀薄膜光伏太阳能电池通过差分进化算法。这将优化用于最大的光伏发电效率。此外，将对域和系数衍生物进行表征和实施，以允许敏感性计算以及基于梯度的优化的使用。详细的光子和电气建模，具有双重周期性的背面反射器和非均匀的光吸收层，还可以允许太阳能电池设计方法的主要扩展，除了产生最大的最大光伏电动电力生成效率的最佳设计。