CAREER: Photovoltaic Devices with Earth-Abundant Low Dimensional Chalcogenides

非技术：太阳提供了丰富的可再生能源，如风能、太阳能和水力发电。太阳能电池，也被称为光伏装置，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。仍然有一些问题限制了进一步的采用。其中包括昂贵或有毒原料的掺入，以及对能源密集型、高温生产工艺的需求。该项目将研究一种基于低维硫化物作为光吸收剂的新兴太阳能技术。这些材料富含土壤，无毒，在环境条件下暴露在阳光下稳定。它们还可以在相对较低的温度下加工，原材料消耗更少，碳足迹更少，这使得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。本项目旨在通过先进的器件工程，显著提高基于低维硫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对社区产生影响。该计划将向青年学生介绍和推广清洁能源概念和太阳能技术。PI还将参加为当地中学教师举办的校园材料夏令营，进行介绍讲座并提供太阳能技术的实际演示。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的学生，从事科学和工程职业。该项目由电气、通信和网络系统部的电子、光子学和磁性器件项目和综合活动办公室的刺激竞争研究（EPSCoR）项目共同资助。技术：该项目的目标是了解基于地球上丰富的低维非立方硫族化物吸收剂的新型薄膜光伏（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。多晶低维硫系吸收剂具有各向异性原子链和固有的良性晶界，具有独特的各向异性载流子输运行为和较强的晶界缺陷容忍度。该项目将解决相当多的基础材料和器件挑战，以实现高性能低维硫化物基光伏器件。结合器件级表征将开展以下四项工作：(1)了解低维硫系吸收层的各向异性生长机制，以及它们如何影响原子链中的载流子输运和器件性能；(2)采用合金化方法调整低维硫族化合物吸收体的带隙，使带隙优化后的光电压最大化，光电流损耗最小化；(3)以第一性原理密度泛函理论计算为理论预测指导，设计低维硫化物基光伏器件中的缺陷和界面，减少载流子重组位点，增加载流子提取；(4)进行外源掺杂工程，提高低维硫化物基光伏器件的光生载流子密度和载流子寿命。从根本上说，本项目将阐明低维硫化物基光伏器件中吸收材料微观结构、光生载流子输运特性和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。

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.