CAREER: Understanding and Quantifying Ion Migration and Diffusion in Two-Dimensional Halide Perovskite Heterostructures

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。非技术描述：卤化物钙钛矿半导体最近在太阳能电池和发光二极管等器件中引起了相当大的关注。然而，它们的稳定性差导致设备寿命短，妨碍了广泛使用。一个特别的挑战是离子的运动改变了钙钛矿的电子性质。因此，了解离子输运对解决稳定性问题至关重要。PI将从二维钙钛矿中开发新的结构，并量化离子在热、光和电偏压下的扩散和迁移。了解这些基本问题将有助于研究人员设计出稳定性更高的钙钛矿。该项目还为本科生和研究生提供跨学科培训。他们将获得材料科学、化学和电气工程以及半导体技术领域所需的批判性思维和解决问题的能力。技术描述：准确量化卤化物钙钛矿中的离子输运是具有挑战性的。目前的理解主要是基于传统的电荷输运研究，其中电子的贡献和阳离子和阴离子的共同运动很难分离。此外，离子扩散研究仅限于晶界和缺陷起关键作用的多晶薄膜。在这个项目中，一种新的外延生长的二维钙钛矿异质结构，一种微观上定义良好的扩散偶联，将被制成并用作探测离子迁移和扩散的平台。该项目将建立一个全面的横向和纵向二维卤化物钙钛矿异质结构家族；定量离子在不同外界刺激下的扩散和迁移；阐明离子扩散和迁移机理；确定最有希望的材料稳定策略；最后演示具有增强稳定性的概念验证设备。该项目的教育目标是在普渡大学建立一个跨学科的材料科学项目，超越科学和工程学科之间的传统界限，培养我们的下一代科学家和工程师。具体而言，将开发突破本科和研究生教育传统界限的新课程和新教学方法。提高公众对材料科学和半导体的认识是该项目的另一个重要目标。最后，将通过与发展中国家（例如哥伦比亚和印度尼西亚）的伙伴关系建立一个有影响力的全球科学和教育网络。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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Non-Technical Description: Halide perovskites semiconductors have recently attracted considerable attention for devices such as solar cells and light-emitting diodes. However, their poor stability results in devices with short lifetimes, precluding widespread use. One particular challenge is that movement of ions alters the electronic properties of perovskites. Thus, understanding ion transport is essential to solve the stability problem. The PI will develop novel structures from two-dimensional perovskites and quantify how ions diffuse and migrate under heat, light, and electrical bias. Understanding these fundamental questions will help researchers design perovskites with enhanced stability. This project also provides interdisciplinary training to undergraduate and graduate students. They will gain critical-thinking and problem-solving skills needed for careers in materials science, chemical and electrical engineering, and semiconductor technology.Technical Description: Accurately quantifying ion transport in halide perovskites is challenging. The current understanding is based primarily on conventional charge transport studies, where the contribution from electrons and co-movement of cations and anions is difficult to separate. Furthermore, ionic diffusion studies have been limited to polycrystalline thin films where grain boundaries and defects play critical roles. In this project, novel epitaxially grown 2D perovskite heterostructures, a microscopically well-defined diffusion couple, will be fabricated and used as a platform to probe ionic migration and diffusion. This project will establish a comprehensive family of lateral and vertical 2D halide perovskite heterostructures; quantify ionic diffusion and migration under different external stimuli; elucidate the ionic diffusion and migration mechanism; identify the most promising materials stabilization strategies; and finally demonstrate proof-of-concept devices with enhanced stability. The education objective of the project is to build an interdisciplinary materials science program at Purdue University that transcends traditional boundaries between science and engineering disciplines to educate our next-generation scientists and engineers. Specifically, new curriculum and new teaching methods that cut-across traditional boundaries for undergraduate and graduate education will be developed. Raising public awareness of materials science and semiconductors is another important objective of this project. Finally, an impactful global network of science and education through partnership with developing countries (e.g., Colombia and Indonesia) will be built.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.