Unravelling the Abnormal Thermo-Mechanical Behavior of 2D Hybrid Organic-Inorganic Perovskites

该奖项支持的研究旨在调查温度如何影响二维杂化有机-无机钙钛矿的机械行为，并揭示这种热-机械行为的起源。这些材料是新兴的低成本、高性能半导体材料，在各种能源和电子应用中具有巨大的潜力，包括太阳能电池、晶体管、传感器和柔性电子产品。机械应变和温度波动的共存在此类应用中普遍存在，并导致机械故障问题，严重阻碍了商业可行性。然而，二维杂化有机-无机钙钛矿的热力学行为仍然难以捉摸。这个研究项目将通过使用原子力显微镜系统地测量这些材料的机械性能随温度的变化来弥补这一知识差距。这项研究的发现有可能延长使用二维混合有机-无机钙钛矿的能源和电子设备的寿命。此外，它可以加快由这些材料制成的低成本高效太阳能电池的商业化，极大地促进了美国政府清洁能源目标的实现。该项目还将为德克萨斯农工大学（一所西班牙裔服务学院）的研究生和本科生提供教育和培训机会，并通过校园K-12和社区外展活动促进STEM教育/职业。与三维或其他低维材料相比，二维杂化有机-无机钙钛矿表现出独特的平面内热力学行为。该项目的总体目标是形成对热力学行为的基本和全面的理解，并揭示二维杂化有机-无机钙钛矿的结构起源。在受控温度下，先进的基于扫描探针的纳米力学表征技术将被用于系统地研究这些材料在面内和面外方向上的温度依赖力学性能。该项目将测试一个中心假设，即有机间隔分子及其界面的热响应会引起二维有机-无机杂化钙钛矿的有趣热力学行为。有机间隔分子的热响应将通过调整二维杂化有机-无机钙钛矿的结构参数来设计，并直接与材料的热-机械行为相关，其中机械解释将由摩擦力显微镜测量的二维层之间的界面剪切强度提供。该研究成果将为工程、设计和优化二维杂化有机-无机钙钛矿在技术感兴趣的温度范围内的机械可靠性和应变耦合半导体性能提供不可或缺的见解。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 supports research which aims to investigate how temperature influences the mechanical behavior of 2D hybrid organic-inorganic perovskites and uncover the origin of such thermo-mechanical behavior. These materials are burgeoning low-cost, high-performance semiconductor materials with great potential in various energy and electronics applications, including solar cells, transistors, sensors, and flexible electronics. The coexistence of mechanical strain and temperature fluctuations is universally found in such applications and causes mechanical failure issues that significantly hinder commercial viability. However, the thermo-mechanical behavior of 2D hybrid organic-inorganic perovskites remains elusive. This research project will bridge this knowledge gap by systematically measuring the mechanical property change of these materials as a function of temperature using atomic force microscopy. The findings of this research have the potential to extend the lifetime of energy and electronic devices using 2D hybrid organic-inorganic perovskites. Additionally, it can expedite the commercialization of low cost and efficient solar cells made of these materials, greatly facilitating the realization of the US government’s clean energy goals. This project will also provide opportunities to educate and train graduate and undergraduate students at Texas A&M University, a Hispanic Serving Institute, and promote STEM education/careers through on-campus K-12 and community outreach activities. 2D hybrid organic-inorganic perovskites manifest a uniquely different in-plane thermo-mechanical behavior compared to their 3D counterparts or other low-dimensional materials. The overarching goal of this project is to form a fundamental and comprehensive understanding of the thermo-mechanical behavior and unveil the structural origin found in 2D hybrid organic-inorganic perovskites. Advanced scanning probe-based nanomechanical characterization techniques at controlled temperatures will be employed to systematically investigate the temperature-dependent mechanical properties of these materials along both in-plane and out-of-plane directions. The project will test the central hypothesis that the thermal response of the organic spacer molecules and their interfaces give rise to the interesting thermo-mechanical behavior of 2D hybrid organic-inorganic perovskites. The thermal response of the organic spacer molecules will be engineered by tuning the structural parameters of 2D hybrid organic-inorganic perovskites, and directly correlated to the attendant thermo-mechanical behavior of the materials, where the mechanistic explanation will be provided by the interfacial shear strength between the 2D layers measured with friction force microscopy. The research outcomes will offer indispensable insights to engineer, design, and optimize mechanical reliability and the strain-coupled semiconductor performance of 2D hybrid organic-inorganic perovskites across the technologically interested temperature range.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.