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，但小型光伏发电机(太阳能电池)必须变得无处不在，人类的进步才能真正不受能源经济的限制。首席研究人员(PI)利用之前NSF拨款下开发的集成光电子计算机模型，证明了包含具有最佳电气性能的吸收器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提高，与更重的标准太阳能电池竞争。一旦制造出来，这种太阳能电池可以被整合到可穿戴设备、纺织品、汽车车顶等中，并且部署的基础设施比目前的晶硅设备更少。对设计的进一步改进需要结合捕光结构，例如通过分级带隙参数来与发电层的组成联合优化的减反射涂层以提高对光的吸收。此外，还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，并研究几种具有简化带隙分级的新材料组合。这是一个多学科的项目，有两个主要目标：数学和物理。其数学目标是通过(I)使用现代数值分析方法来提高光子学求解器的效率，以及(Ii)提高应用于带电粒子输运漂移-扩散系统的杂交不连续Galerkin方法(HDG)有限元方法的稳健性和可靠性。特别是，PI将通过将严格耦合波法(RCWA)与C方法相结合来分析和实施一种全新的方法来求解2D和3D中的麦克斯韦方程。由于用于漂移-扩散问题的HDG解算器需要改进的稳健性和效率来处理更适合制造的分层设计，PI将分析并实施双加权残差方法来估计总电流的后验误差，并研究将Anderson加速用于非线性解算器。预计在该项目上开发的软件将对更广泛的光子学社区有用。物理目标是使用新开发的快速和自适应求解器，以便改进的算法可以用于同时优化捕光结构和带隙分级参数。捕光结构将包括多层减反射涂层、纳米锥体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。可穿戴式太阳能电池不仅可以在阳光下运行，还可以在室内光线下运行。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.