CAREER: Photovoltaic Devices with Earth-Abundant Low Dimensional Chalcogenides

非技术性：太阳提供了丰富的可再生能源，如风能、太阳能和水力。太阳能电池，也称为光伏器件，直接将阳光转化为电能。效率的显著提高和成本的降低导致了太阳能的广泛采用。但仍有一些问题限制了进一步采用。这些包括掺入昂贵或有毒的原材料以及需要能源密集型高温生产工艺。本计画将研究一种新兴的太阳能技术，其基础是低维硫族化合物作为光吸收体。这些材料在地球上丰富，无毒，在环境条件下暴露于阳光下时稳定。它们还可以在相对较低的温度下加工，原材料消耗较少，碳足迹较少，使这种新兴的太阳能技术具有潜在的成本竞争力和可持续性。该项目旨在通过先进的器件工程显著提高基于低维硫属化物的太阳能电池的效率。其目的是为这种新开发的太阳能技术的商业化铺平道路，以提供更实惠的太阳能电力。该项目将通过与当地小学的长期合作关系影响社区。PI将接触年轻学生，介绍和促进清洁能源概念和太阳能技术。此外，首席研究员亦会参与为本地中学教师而设的校园教材夏令营，讲解太阳能技术，并亲身示范有关技术。然后，教师可以在他们的家庭学校实施这些课程，以吸引更多的学生，特别是那些来自少数民族和代表性不足的群体，追求科学和工程事业。该项目由电气、通信和网络系统部的电子、光子学和磁器件项目以及综合活动办公室的刺激竞争研究的既定计划（EPSCoR）项目共同资助。技术：该项目的目标是了解一类基于地球丰富的低维非立方硫族化物吸收体的新型薄膜光伏（PV）器件的电子和光子特性，以实现高效、可持续和负担得起的太阳能。多晶低维硫族化物吸收体具有各向异性的原子链和本质上良性的晶界，这提供了独特的各向异性载流子输运行为和大的晶界缺陷容限。相当多的基本材料和设备的挑战将在这个项目中得到解决，以实现高性能低维硫族化物为基础的光伏器件。本论文将结合器件级的特性研究，完成以下四项工作：（1）了解低维硫族吸收层的各向异性生长机制，以及它们对原子链中载流子输运和器件性能的影响;（二）通过合金化方法调整低维硫族化物吸收体的带隙，以最大化具有优化带隙的光电压并最小化光电流损失;（3）在第一性原理密度泛函理论计算的理论预测指导下，对低维硫族化合物光伏器件中的缺陷和界面进行工程设计，以减少载流子复合位点，增加载流子提取;（4）进行非本征掺杂工程，以增加低维硫族化合物光伏器件的光生载流子密度和载流子寿命。从根本上讲，这个项目将阐明吸收材料的微观结构，光生载流子输运特性，和低维硫族化物为基础的光伏器件的器件性能之间的关系。最终，该项目将为下一代高效低成本薄膜光伏技术的未来发展铺平道路。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。

Nontechnical:The sun provides abundant sources of renewable energy such as wind, solar, and hydro power. Solar cells, also known as photovoltaic devices, directly convert sunlight into electricity. Dramatic efficiency improvements and cost reductions have led to widespread adoption of solar power. There are still problems that limit further adoption. These include incorporation of expensive or toxic raw materials as well as the need for energy intensive, high temperature production processes. This project will investigate an emerging solar technology based on low dimensional chalcogenides as light absorbers. These materials are earth abundant, non-toxic and stable upon exposure to sunlight under ambient conditions. They can also be processed at relatively low temperatures with fewer raw materials consumption and less carbon footprint, making this emerging solar technology potentially cost-competitive and sustainable. This project aims to significantly improve the efficiency of solar cells based on low-dimensional chalcognides through advanced device engineering. The aim is to pave the way to commercialize this newly developed solar technology to provide more affordable solar electricity. This project will impact the community through a long-term partnership with local elementary schools. The PI will reach out to young students to introduce and foster clean energy concepts and solar technologies. The PI will also participate in an on-campus material summer camp for the local secondary school teachers, giving introduction lectures and providing hands-on demonstrations of solar technologies. Teachers can then implement these lessons in their home schools to attract more students, especially those from minority and underrepresented groups, to pursue science and engineering careers. This project is jointly funded by the Electronics, Photonics, and Magnetic Devices program of the Division of Electrical, Communications, and Cyber Systems and the Established Program to Stimulate Competitive Research (EPSCoR) program of the Office of Integrative Activities.Technical:The objective of this project is to understand the electronic and photonic properties of a new class of thin-film photovoltaic (PV) devices based on earth-abundant low-dimensional noncubic chalcogenide absorbers to achieve highly efficient, sustainable, and affordable solar energy. Polycrystalline low dimensional chalcogenide absorbers possess anisotropic atomic chains and intrinsically benign grain boundaries, which provide unique anisotropic carrier transport behaviors and great grain boundary defect tolerance. Considerable fundamental material and device challenges will be addressed in this project to achieve high-performance low dimensional chalcogenides based PV devices. The following four tasks with a combination of device-level characterization will be carried out: (1) understand the anisotropic growth mechanisms of the low dimensional chalcogenide absorbers layer, and how they impact the carrier transport in the atomic chains and device performance; (2) tailor bandgap of low dimensional chalcogenide absorbers by the alloying approach to maximize the photovoltage with optimized bandgap and minimize the photocurrent loss; (3) engineer defects and interfaces in the low dimensional chalcogenides based PV devices to reduce the carrier recombination sites and increase carrier extraction with a guide of theoretical prediction using first-principle density functional theory calculation; (4) conduct extrinsic doping engineering to increase the photogenerated carrier density and carrier lifetime of the low dimensional chalcogenides based PV devices. Fundamentally, this project will elucidate the relationship between absorbers material microstructure, photogenerated carrier transport properties, and device performance in low dimensional chalcogenide-based PV devices. Eventually, this proposed project will pave the way for the future development of next-generation high-efficiency low-cost thin film PV technologies.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.