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材料获得了巨大的研究兴趣，其效率现在接近传统的硅器件。此外，它们允许更可扩展的制造和开发具有两个不同吸收体的更高效率的串联器件。钙钛矿具有复杂的晶体结构，具有多种形式的无序。尽管有这种复杂性，但它们有很强的能力来运输电荷，而不会造成降低效率的损失。然而，关于无序的作用及其对产生的光电流的影响的基本问题仍然没有得到回答。该项目使用先进的超快光谱学来测量无序对钙钛矿中能量和载流子流动的影响。这些结果直接与随后的设备行为相关联。总体而言，该项目提供了对材料基本物理的理解，同时也提供了提高设备效率的实用方法的指导。主要调查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、在当地游乐园的动手演讲和在线课程向公众开放。该项目的目标是测量缺陷和移动阳离子造成的空间不规则性对钙钛矿型薄膜光伏材料和器件中激子和自由载流子输运的影响。多维相干光谱学实验将在一个紧密的反馈回路中进行，通过受控和可扩展的合成，使人们能够对微观载流子传输有新的理解，从而在设备效率方面产生变革性的收益。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谱实现，量化缺陷密度对载流子输运和动力学的影响；测量静态和动态阳离子无序对载流子寿命的影响；通过光学实验和器件制造的紧密结合，优化材料组成和器件结构；表征可伸缩沉积技术及其在不同尺寸尺度下对薄膜异质性的影响。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，以及b)能量耦合沉积钙钛矿材料，以产生更好的薄膜质量，用于可伸缩器件的制造。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.