Collaborative Research: Integrated Optoelectronic Optimization of Thin-Film Solar Cells with Light-Trapping Structures

尽管近年来标准厚晶硅太阳能电池的成本迅速下降，但小规模的光伏发电机（太阳能电池）必须无处不在，才能使人类进步真正不受能源经济的限制。利用先前在NSF资助下开发的集成光电计算机模型，首席研究人员（pi）已经表明，含有具有最佳梯度电性能的吸收层的薄膜太阳能电池的理论发电效率可以超过34%，比以前的设计有很大的提高，并且与更重的标准太阳能电池竞争。一旦制造出来，这种太阳能电池就可以应用于可穿戴设备、纺织品、汽车车顶等，而且比目前的晶体硅设备所需的基础设施更少。进一步改进设计需要加入光捕获结构，例如通过分级带隙参数与发电层的组成共同优化的抗反射涂层来提高光的吸收。此外，需要研究更适合制造的简化设计。这些额外的步骤需要对光电模型进行数学改进，并研究几种简化带隙分级的新材料组合。这是一个多学科项目，有两个主要目标：数学和物理。数学目标是通过(i)使用现代数值分析方法来提高光子求解器的效率，以及（ii）提高应用于带电粒子输运的漂移扩散系统的杂化不连续伽辽金方法（HDG）有限元方法的鲁棒性和可靠性来增强集成光电模型。特别是，pi将分析和实现一种全新的方法，即将严格耦合波方法（RCWA）与C方法相结合，用于求解二维和三维麦克斯韦方程组。由于漂移扩散问题的HDG解算器需要提高鲁棒性和效率，以处理更适合制造的分层设计，pi将分析并实现双加权残差方法来估计总电流的后检误差，并研究在非线性解算器中使用安德森加速度。预计该项目开发的软件将对更广泛的光子学社区有用。物理目标是利用新开发的快速自适应求解器，使改进的算法可以同时优化光捕获结构和带隙分级参数。光捕获结构将包括多层抗反射涂层、纳米锥阵列以及两者的组合。PIs希望推动彩色太阳能电池的发展，为衣服、车顶、帐篷等上的微型电子和光学设备提供动力。可穿戴太阳能电池不仅可以在阳光下工作，还可以在室内光线下工作。该奖项反映了美国国家科学基金会的法定使命，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。

Although recent years have seen a rapid drop in the cost of standard thick crystalline-silicon solar-cells, small-scale photovoltaic generators of energy (solar cells) must become ubiquitous for human progress to become truly unconstrained by energy economics. Using an integrated optoelectronic computer model developed under a previous NSF grant, the Principal Investigators (PIs), have shown that thin-film solar cells containing absorber layers with optimally graded electrical properties can have theoretical electrical generation efficiencies of over 34%, a large increase over previous designs and competitive with heavier standard solar cells. Once manufactured, such solar cells could be incorporated in wearables, textiles, car roofs, etc, and deployed with less infrastructure than current crystalline-silicon devices. Further improvement to the design requires the incorporation of light-trapping structures, such as antireflection coatings to improve the absorption of light, that are jointly optimized with the composition of the electricity generating layers by grading the bandgap parameters. In addition, simplified designs better suited to manufacture need to be investigated. These additional steps require mathematical improvement to the optoelectronic model, and the investigation of several new combinations of materials with simplified bandgap grading. This is a multidisciplinary project with two major goals: mathematical and physical. The mathematical goal is to enhance the integrated optoelectronic model by (i) using modern methods of numerical analysis to improve the efficiency of the photonics solver, and (ii) improving the robustness and reliability of the Hybridizable Discontinuous Galerkin method (HDG) finite element method applied to the drift-diffusion system for charged-particle transport. In particular, the PIs will analyze and implement a completely new approach by hybridizing the rigorous coupled-wave approach (RCWA) with the C method for solving Maxwell’s equations in 2D and 3D. As the HDG solver for the drift-diffusion problem needs improved robustness and efficiency to handle layered designs more suitable for manufacturing, the PIs will analyze and implement a dual-weighted residual approach to a posteriori error estimation of the total current and investigate the use of Anderson acceleration for the non-linear solver. It is expected that the software developed on this project will be useful to the wider photonics community. The physical goal is to use the newly developed fast and adaptive solver so that the improved algorithms can be used to simultaneously optimize light-trapping structures and bandgap grading parameters. The light-trapping structures will include multilayered antireflection coatings, nanocone arrays, and combinations of both. The PIs expect to spur the development of colored solar cells to power miniature electronic and optical devices on clothes, car roofs, tents, etc. Wearable solar cells could be designed to perform not only in sunlight but also in indoor light.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.