CAREER: Developing solution-based thin-film chalcogenide perovskites

光伏发电是一种可再生的清洁能源，正迅速成为美国最便宜的能源形式之一。然而，要实现光伏技术的广泛应用，仍需要许多关键的科学进步。这包括发现和开发新的光伏材料，更好地理解和控制它们的性质。这个NSF CAREER奖项目由材料研究部固态和材料化学项目支持，旨在开发一类新的材料——硫系钙钛矿——用于低成本、无毒、稳定的光伏发电，由于其性能的改善，可以取代现有的技术。一些挑战限制了这种材料的实验进展。为了克服这些问题，佛罗里达大学Charles Hages教授的研究小组开发的新技术被用于合成这些新材料。这包括使用极小的（纳米级）构建块来独特地控制材料组装。实验工作以理论工作为指导，通过先进的表征技术来确定以前未实现的有前途的材料。与这项研究相结合的是一项针对服务不足的当地社区的跨代STEM教育和推广计划。这包括(1)为当地独立生活和辅助生活社区的老龄化人口量身定制的可再生能源STEM教育计划，以及(2)气候变化和可再生能源教育方面的K-12教育和青年计划。这项教育计划的成果是：提高人们对科学和技术对社会的价值、学术界的作用以及公共资金对这些追求的价值的认识；增加公众对科技的参与；提高科学素养，特别是在代表性不足的社区。该项目由材料研究部固态与材料化学项目支持，建立了一种新的基于溶液的硫系钙钛矿合成方法，并通过实验实现了具有理想光电性能的新型硫系钙钛矿化合物。硫系钙钛矿是一种新兴的半导体，具有取代普遍存在的有机-无机杂化金属卤化物钙钛矿作为高性能光伏吸收剂的潜力。这是由于它们预测的稳定性增强，有利的电荷传输和吸收特性，以及无毒性质，同时保持钙钛矿典型的缺陷耐受性和高光电可调性。然而，这一领域的实验研究很少，导致理论实验知识差距很大。此外，报道的高温合成反应时间长，极大地限制了它们对可调材料化学的适应性，以控制它们的材料性质和合成成薄膜。为了解决这个问题，佛罗里达大学Charles Hages教授的研究小组沿着三个具体目标进行研究。目的1建立了一种用亚稳溶液基纳米颗粒前驱体反应退火法制备薄膜硫系钙钛矿的新方法。Aim 2提出了该材料空间的新相稳定性分析，并将重点放在几个以前未实现的硒基硫系钙钛矿上。目的3提出了一种全光学表征策略来绘制这些新化合物的合成-结构-性质关系。这项研究与跨代STEM教育和可再生能源推广相结合，其中包括为服务不足的当地老龄化社区和K-12学生开发和提供量身定制的教育模块。研究还与研究生和本科生在教学、技术交流和新兴能源技术方面的培训和教育相结合。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。

NON-TECHNICAL SUMMARYPhotovoltaics are a renewable and clean source of energy which are rapidly becoming one of the cheapest forms of energy available in the US. However, many key scientific advancements are still needed to achieve widespread adoption of photovoltaic technology. This includes discovering and developing new photovoltaic materials and better understanding and controlling their properties. This NSF CAREER award project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, aims to develop a new class of materials – chalcogenide perovskites – for low-cost, non-toxic, and stable photovoltaics which can replace existing technologies due to their improved properties. Several challenges limit experimental progress for this material. To overcome these, novel techniques developed by Prof. Charles Hages’ research group at the University of Florida are used to synthesize these new materials. This includes the use of extremely small (nanoscale) building blocks to uniquely control material assembly. Experimental work is guided by theoretical work to identify previously unrealized promising materials whose properties are measured through advanced characterization techniques. Integrated with this research is a cross-generational STEM education and outreach plan targeting the underserved local community. This includes (1) a tailored STEM education program in renewable energy for the aging population at local independent- and assisted-living communities, and (2) K-12 education and youth programs in climate change and renewable energy education. The outcomes of this educational plan are: to enhance the perception of the value of science & technology to society, the role of academia, and the value of public funding for these pursuits; to increase public engagement with science and technology; and to enhance scientific literacy, particularly among underrepresented communities.TECHNICAL SUMMARYThis NSF CAREER award project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, establishes a new solution-based synthesis for chalcogenide perovskites and experimentally realizes new chalcogenide perovskite compounds with desirable optoelectronic properties for photovoltaics. Chalcogenide perovskites are an emerging class of semiconductor with the potential to replace the ubiquitous organic-inorganic hybrid metal halide perovskites as a high-performance photovoltaic absorber. This is a result of their predicted enhanced stability, favorable charge transport and absorption properties, and non-toxic nature – while maintaining the defect tolerance and high optoelectronic tunability typical of perovskites. However, minimal experimental research is reported in this field, resulting in a significant theory experiment knowledge gap. Furthermore, the reported high-temperature syntheses with long reaction times significantly limits their amenability to tunable materials chemistry for controlling their material properties and synthesis into thin films. To address this, Prof. Charles Hages’ research group at the University of Florida pursues research along three specific aims. Aim 1 establishes a new synthesis for thin-film chalcogenide perovskites by reactive annealing of metastable solution-based nanoparticle precursors. Aim 2 proposes a new phase stability analysis for this material space and rationalizes a focus in several previously unrealized selenium-based chalcogenide perovskites. Aim 3 proposes an all-optical characterization strategy to map the synthesis-structure-property relationship of these new compounds. This research is integrated with cross-generational STEM education and outreach in renewable energy, which includes developing and delivering tailored educational modules for the underserved local aging community and K-12 students. Research is also integrated with training and education for graduate and undergraduate students in teaching, technical communication, and in emerging energy 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.