Bismuth Rudorffites: Promising New Materials for the Top Cell in Solution Processed Tandem PV

非技术描述：降低太阳能发电总成本的有效方法是提高太阳能电池的功率转换效率，特别是在制造成本增加最少的情况下。这个目标可以通过在硅太阳能电池上增加一个低成本的高带隙太阳能电池来实现。迄今为止，这种顶级电池最有前途的材料是混合钙钛矿。这些新材料具有非常高的性能，但它们含有铅，铅是有毒的，会引起环境问题。这个项目的重点是开发新的低毒性铋基高带隙半导体，这种半导体有可能被用来替代。该团队正在探索最近发现的一类称为rudorffites的铋材料，并正在建立对这些无毒半导体材料结构，性能和加工之间关键关系的理解。这项基础研究可以通过开发无毒元素的低成本串联太阳能电池来产生重大的社会影响。此外，该项目还为一名研究生、一名博士后学者和几名本科生提供培训，并通过西雅图太平洋科学中心和清洁能源研究所的清洁能源大使项目吸引公众。技术描述：铋基半导体是一种有趣的无毒光电材料，因为Bi3+与6s2孤对的部分氧化有望导致与铅基杂化钙钛矿相似的缺陷耐受性。最近发现的铋rudorffites特别令人感兴趣，因为它们具有适合串联太阳能电池的高带隙。由铋rudorffites制成的太阳能电池有几个百分比的效率，但它们有潜力获得更高的效率。在这个项目中，研究人员正在进行一系列基础研究，以探索溶液生长铋rudorffite在光电应用中的潜力，了解导致潜在性能限制的基本过程，并制定克服这些限制的策略。初步研究表明，纳米层形貌和掺杂/合金化对这些材料的光电质量有很大影响。该项目采用组合喷涂方法合成大量合金/掺杂成分，绝对强度光致发光评估准费米能级分裂，基于光导的方法评估载流子扩散长度。目标是将光伏材料的结构和加工与最重要的材料性能指标联系起来。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 Description: An effective way to decrease the overall cost of electricity from solar energy is to increase the power conversion efficiency of solar cells, particularly if it can be accomplished with minimal increase in manufacturing cost. This goal can be achieved by adding a low-cost high-bandgap solar cell on top of a silicon solar cell. To date, the most promising materials for this top-cell are hybrid perovskites. These new materials have extraordinarily high performance, but they contain lead, which is toxic and raises environmental concerns. This project focuses on developing new low-toxicity bismuth-based high bandgap semiconductors that can potentially be used instead. The team is exploring a recently discovered class of bismuth materials called rudorffites and is building an understanding of the critical relationships between material structure, properties, and processing for these non-toxic semiconductors. This basic research could have significant societal impact by enabling the development of low-cost tandem solar cells from non-toxic elements. Furthermore, the project provides training of a graduate student, a postdoctoral scholar, and several undergraduates, as well as engage the public though the Pacific Science Center in Seattle and the Clean Energy Institute's Clean Energy Ambassadors program.Technical Description: Bismuth-based semiconductors are interesting non-toxic optoelectronic materials since the partial oxidation of Bi3+ with the 6s2 lone pair is expected to lead to similar defect tolerance as the lead-based hybrid perovskites. The recently discovered bismuth rudorffites are of particular interest since they exhibit high bandgaps suitable for tandem solar cells. Solar cells from bismuth rudorffites have a few-percentage efficiency, but they have the potential for much higher efficiency. In this project, investigators are conducting a body of fundamental research to explore the potential of solution grown bismuth rudorffites for optoelectronic applications, to understand the fundamental processes responsible for potential performance limitations and to develop strategies to overcome them. Preliminary research shows that nanoscale layer morphology and doping/alloying have a tremendous effect on the optoelectronic quality of these materials. The project utilizes combinatorial spray coating methods to synthesize a large number of alloy/doping compositions, absolute intensity photoluminescence to assess quasi-Fermi level splitting, and photoconductivity-based methods to assess the carrier diffusion length. The goal is to connect structure and processing with the most important material performance metrics for photovoltaic materials.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.