Collaborative Research: Highly mismatched GaSb-GaAs thin film multijunction solar cells for high efficiency

摘要：非技术性：罗彻斯特理工学院和加州大学洛杉矶分校提议展示一种高度失配的、基于Sb的多结太阳能电池，具有低缺陷密度和最佳带隙，效率超过50%。一种名为界面失配阵列的新生长技术将被用于开发拟议的太阳能电池器件。这些器件将能够在效率方面取得革命性的进步，或许最终有可能将高效率的III-V技术转移到低成本的硅衬底上。所提出的工作将大大降低多结太阳能电池的成本，同时提高能量转换效率。此外，拟议的材料生长方法可能会对探测器、激光和存储设备等领域产生潜在影响。这项工作还将支持多层次教育活动的发展。研究生和本科生都将接受尖端材料工程和设备物理方面的培训。此外，这两位主要研究人员将通过一系列涉及材料和太阳能转换之间的关系的讲座和演示，参与他们实验室的高中生暑期指导。技术：该方案的技术目标是通过使用GaSb界面失配生长技术将Sb基材料集成到晶格匹配的InGaP2/GaAs工艺中，从而获得接近最佳带隙的五结太阳电池。界面失配生长将允许在GaAs上以晶格失配的方式生长高质量的GaSb，而不需要复杂且生长密集的阶梯级缓冲层。所提出的器件将由晶格匹配的(Al)InGaP2，AlGaAs和GaAs作为前三个单元，单个界面失配跃迁，以及晶格匹配的1.1 eV AlGaSb和0.73 eV GaSb作为最后两个单元。团队成员已经演示了GaSb的界面失配生长，这使得他们能够在GaAs上实现高质量材料的晶格失配生长，而不需要复杂和生长密集的阶梯级缓冲层。在第一年，将开发在GaSb/GaAs模板上的AlGaSb和在GaAs衬底上的InGaP以及所需的隧道结，目的是了解光学和电学特性。在第二和第三年，将开发拟议的三结型和五结型太阳能电池。所有这些步骤都将得到详细的材料表征和基于物理的器件模拟的支持，以优化器件设计并提高Sb基光电子器件的预测能力。

Abstract: Non-Technical:Rochester Institute of Technology and University of California Los Angeles propose to demonstrate a highly mismatched, Sb-based multi-junction solar cell with low defect density and optimal bandgaps, with efficiency over 50%. A novel growth technique known as interfacial misfit array will be used to develop the proposed solar cell devices. These devices would be capable of revolutionary advances in efficiency and perhaps the eventual possibility of transferring the high efficiency III-V technology to a low cost Si substrate. The proposed work will significantly reduce multi-junction solar cell cost and at the same time increase energy conversion efficiency. As well, the proposed material growth methods can have potential impact on areas such as detectors, lasers and memory devices. This work will also support the development of educational activities at multiple levels. Both graduate and undergraduate students will receive training in leading-edge materials engineering and device physics. As well, both principle investigators will be involved in high school student summer mentoring in their laboratories, through a series of lectures and demonstrations involving the relationship between materials and solar energy conversion. Technical:The technical aim of this proposal is to gain access to near optimal band gaps for a five junction solar cells by integrating Sb-based materials into the lattice matched InGaP2/GaAs technology using the GaSb interfacial misfit growth technique. Interfacial misfit growth will allow for the lattice-mismatched growth of high quality GaSb on GaAs without the need for a complex and growth intensive step-grade buffer layer. Proposed devices will be comprised of lattice matched (Al)InGaP2, AlGaAs and GaAs as the top three cells, a single interfacial misfit transition and lattice matched 1.1 eV AlGaSb and 0.73 eV GaSb as the bottom two cells. Team members have already demonstrated the interfacial misfit growth of GaSb, which allows them to achieve the lattice-mismatched growth of high quality materials on GaAs, without the need for a complex and growth intensive step-grade buffer layer. In the first year, AlGaSb on GaSb/GaAs templates and InGaP on GaAs substrates along with required tunnel junctions will be developed, with the aim of understanding of optical and electrical properties. In the second and third years, the proposed three junction and five junction solar cells will be developed. All of the steps will be supported by detailed materials characterization as well as physics-based device simulations, to optimize the device design and imporve the predictiave capabilites for Sb-based optoelectronics devices.