Collaborative Proposal: Multidimensional Tracking of Local Environment-Affected Transport Pathways in Perovskite Solar Cells

有机金属卤化物钙钛矿作为太阳能电池的材料获得了巨大的研究兴趣，它们的效率现在接近传统硅器件的效率。此外，它们允许更可扩展的制造和开发具有两种不同吸收剂的更高效率串联设备。钙钛矿具有复杂的晶体结构和多种无序形式。尽管存在这种复杂性，但它们具有强大的运输能力，不会造成降低效率的损失。然而，关于紊乱的作用及其对产生的光电流的影响的基本问题仍然没有答案。该项目使用先进的超快光谱来测量无序对钙钛矿中能量和载流子流动的影响。这些结果直接耦合到随后的设备行为。总体而言，该项目提供了对材料基本物理的理解，同时也为提高设备效率的实用方法提供了指导。主要研究人员将利用这一研究课题与K-12学生、本科生和社区大学教师进行研究。他们还将通过公开讲座、在当地游乐园的实践演示以及在线课程与公众接触。该项目的目的是测量缺陷和移动阳离子的空间不规则性对钙钛矿薄膜光伏材料和器件中激子和自由载流子输运的影响。多维相干光谱实验将在一个紧密的反馈回路中进行，具有可控和可扩展的合成，从而对微观载流子输运有了新的理解，从而激发设备效率的变革性提高。在钙钛矿材料和光伏器件上进行了实验，以便：1)通过一种新的多维相干光谱实现量化缺陷密度对载流子输运和动力学的影响；2)测量静态和动态阳离子无序对载流子寿命的影响；3)通过光学实验与器件制造的紧密耦合，优化材料组成和器件结构；4)表征可扩展沉积技术及其在不同尺寸尺度下对薄膜非均质性的影响。作为工作的一部分，开发了新的实验方法，包括a)通过多维光谱同时检测光致发光和光电流，b)钙钛矿材料的能量耦合沉积，以提高可扩展器件制造的薄膜质量。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。

Organic metal halide perovskites have gained enormous research interest as materials for solar cells, and their efficiencies are now approaching those of conventional silicon devices. Additionally, they allow for more scalable fabrication and for the development of higher efficiency tandem devices with two different absorbers. Perovskites have a complicated crystal structure with many forms of disorder. Despite this complexity, they have a robust ability to transport charges without losses that reduce efficiency. However, fundamental questions regarding the role of the disorder and its effect on the generated photocurrent remain unanswered. This project uses advanced, ultrafast spectroscopy to measure the effects of disorder on energy and charge carrier flow in perovskites. These results are directly coupled to the subsequent device behavior. Overall, this project provides an understanding of the fundamental physics of the materials while also providing guidance on practical methods to improving device efficiencies. The principal investigators will use this research topic to engage with K-12 students, undergraduate students, and community college teachers in research. They will also reach out to the general public through public lectures, hands-on presentations at a local amusement park, and online classes.The objective of the project is to measure the effect of spatial irregularity from defects and mobile cations on exciton and free carrier transport in perovskite thin-film photovoltaic materials and devices. Multidimensional coherent spectroscopy experiments will be performed in a tight feedback loop with controlled and scalable synthesis enabling new understanding of microscopic carrier transport to spark transformative gains in device efficiency. Experiments are performed on perovskite materials and photovoltaic devices in order to: 1.) quantify the effect of defect density on carrier transport and dynamics through a novel implementation of multidimensional coherent spectroscopy; 2.) measure the effect of both static and dynamic cation disorder on carrier lifetime; 3.) optimize material composition and device architecture through close coupling between optical experiments and device fabrication; and 4.) characterize scalable deposition techniques and their effect on film heterogeneity at varying size scales. As part of the work, new experimental approaches are developed, including a) simultaneous detection of photoluminescence and photocurrent through multidimensional spectroscopy and b) energy-coupled deposition of the perovskite materials to yield improved film quality for scalable device fabrication.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.