Nanoscale spectroscopy of hybrid perovskite solar cells: resolving the role of humidity on device stability through in situ microscopy

摘要：非技术：在美国，高效、低成本的光伏发电技术仍然是成功取代化石燃料技术的关键。目前，美国只有1%的电力来自太阳能。太阳能电池作为一种电力来源的广泛实施的主要挑战是目前的高成本/瓦特。混合钙钛矿是一种非常有前途的制造低成本光伏组件的新材料，但提高器件稳定性是必不可少的，这样这种新兴材料才能有效地用于光伏技术。特别是，当由微米级颗粒组成的钙钛矿暴露于湿度时，器件性能如何变化尚不清楚。为了进一步了解太阳能电池在运行（以及暴露在湿度下）时颗粒的电学性质是如何变化的，该项目将采用一种新的显微镜技术来实时解决形成钙钛矿的颗粒内部发生的变化。这些钙钛矿电响应的“纳米级照片”将用于确定为了实现稳定的器件，应该避免哪些物理和化学过程。该项目的综合教育部分侧重于将研究成果纳入马里兰大学材料科学与工程的两门现有课程，指导本科生和研究生，并通过LeiteLab YouTube频道以不同语言向全球传播科学成果。项目技术描述：基于甲基铵碘化铅的杂化有机/无机钙钛矿是一种新兴材料，具有成为高性能、低成本光伏技术的真正潜力。然而，尽管在过去的几年里取得了显著的进展，但人们仍然缺乏对材料暴露于湿度时变化/降解的原因和方式的理解。本研究的目的是通过实时测量钙钛矿材料降解时发生的变化，以纳米级分辨率阐明湿度在钙钛矿太阳能电池中的作用。通过实施快速照明开尔文探针力显微镜，Leite团队将在16秒内绘制出光产生的电压；因此，当设备运行时，可以实时捕获材料的变化。该项目基于PI在纳米尺度计量方面的专业知识，对能量收集和存储设备的功能进行成像。控制湿度对钙钛矿的负面影响将使这种材料作为一种可靠和低成本的光伏技术得到广泛应用。

Abstract:Nontechnical: An effective high-efficiency and low-cost photovoltaic technology is still required to successfully replace fossil fuel-based technologies in the US. Currently, only 1% of the total US electricity is generated by solar power. The main challenge for the widespread implementation of solar cells as a source of electricity is the current high cost/Watt. Hybrid perovskites are a very promising new material for manufacturing low-cost photovoltaic modules, but improvement in device stability is essential so that this emerging material can be effectively employed as a photovoltaic technology. In particular, it is unknown how the device performance changes when the perovskite, composed by micron-scale grains, is exposed to humidity. To advance the understanding of how the grains' electrical properties are changing while the solar cells are under operation (and exposed to humidity), this project will implement a novel microscopy technique to resolve, in real-time, the changes that take place within the grains forming the perovskites. These "nanoscale photographs" of the electrical response of the perovskites will be used to determine which physical and chemical processes should be avoided for the realization of stable devices. The integrated educational component of this project focuses on incorporating the research findings into two existing courses in Materials Science and Engineering at the University of Maryland, mentoring undergraduate and graduate students, and broadcasting the scientific results through the LeiteLab YouTube Channel in different languages for worldwide dissemination. Technical description of the project: Hybrid organic/inorganic perovskites based on methyl-ammonium lead iodide are an emerging material with true potential for being a high performance and low cost photovoltaic technology. However, despite the remarkable progress over the last few years, there is still a lack in understanding of why and how the material is changing/degrading when exposed to humidity. The goal of this research is to elucidate the role of humidity in perovskite solar cells by measuring in real-time, with nanoscale resolution, the changes that take place when the perovskite material degrades. By implementing fast illuminated-Kelvin probe force microscopy the Leite group will map the photo-generated voltage in 16 seconds; thus, capturing in real-time the material changes while the device is in operando. This project builds upon the PI's expertise in nanoscale metrologies to image the functionality of devices for energy harvesting and storage. Controlling the negative effect of humidity on perovskites will enable the wide implementation of this material as a reliable and low cost photovoltaic technology.