Collaborative Research: Correlating Optoelectronic Properties with Defects in One-Dimensional Perovskite Nanocrystals

金属卤化物钙钛矿材料由于具有优异的光电性能，近年来在太阳能电池、发光二极管、光电探测器、激光和光谱伽马射线探测和/或X射线成像的闪烁体等方面的应用取得了迅速的进展。钙钛矿中的缺陷可以限制载流子的传输并改变载流子浓度。理解和识别钙钛矿结构中缺陷的能力是控制钙钛矿结构器件性能的关键。这项合作研究的目的是将一维钙钛矿纳米晶体的光电性质与缺陷联系起来。这些纳米晶体既可以单独使用，也可以作为组装纳米结构材料和设备的积木。这些设备将用于能源和生物医学应用，包括光电子、光子学、传感器、催化、纳米技术和生物技术等新兴领域。因此，它将基础科学发现转化为有益于社会的技术。该项目为未被充分代表的女性和少数族裔本科生以及高中教师和学生提供了在佐治亚理工学院和加州州立大学贝克斯菲尔德参与纳米材料研究的机会。在一维(1D)金属卤化物钙钛矿中，缺陷的存在有望对载流子的输运行为产生显著影响，从而影响其电学和光电性质。因此，识别、理解、控制和可能地利用钙钛矿晶体中的缺陷是至关重要的。佐治亚理工学院和加州州立大学贝克斯菲尔德分校的这项合作研究旨在制作尺寸精确控制的一维钙钛矿型纳米晶体，仔细研究它们与尺寸相关的光学性质，并利用非接触式介电力显微镜技术，通过直接成像缺陷和光激励下的局部传输势垒，将这些钙钛矿型纳米晶体的光电性质与缺陷关联起来。对这些单分散的一维钙钛矿纳米晶体的光学性质和缺陷特征的系统研究使高质量的钙钛矿纳米材料能够具有所需的光电性能和最小的有害缺陷，从而使它们能够用于各种性能更好的光电设备。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。

Recent research has witnessed rapid advances in metal halide perovskite materials for applications in solar cells, light-emitting diodes, photodetectors, lasers, and scintillators for spectroscopic gamma-ray detection and/or X-ray imaging due to their superior optoelectronic properties. Defects in perovskites can limit the transport of charge carriers and change the carrier concentrations. The ability to understand and recognize defects in perovskites is the key to control the performance in perovskite-based devices. This collaborative research aims to relate optoelectronic properties with defects in one-dimensional perovskite nanocrystals. These nanocrystals can be exploited either individually or as building blocks in the assembly of nanostructured materials and devices. These devices would be used in energy and biomedical applications, including optoelectronics, photonics, sensors, catalysis, nanotechnology, and biotechnology, among other emerging areas. As such, it transitions fundamental scientific discoveries into useful technologies that benefit society. This project offers opportunities for underrepresented female and minority undergraduate students as well as high school teachers and students to participate in nanomaterials research at both Georgia Tech and California State University-Bakersfield. In one-dimensional (1D) metal halide perovskites, defects, if present, are expected to exert a pronounced influence on the carrier transport behaviors and thus the electronic and optoelectronic properties. It is therefore of crucial importance to identify, understand, control, and possibly utilize defects in perovskite crystals. This collaborative research between Georgia Tech and California State University-Bakersfield seeks to craft 1D perovskite nanocrystals with precisely controlled dimensions, scrutinize their dimension-dependent optical properties, and correlate the resulting optoelectronic properties of these perovskite nanocrystals with defects via directly imaging defects and local transport barriers under optical excitations by capitalizing on a contactless dielectric force microscopy technique. The systematic investigation into the optical properties and defect characteristics of these monodisperse 1D perovskite nanocrystals enables the development of high-quality perovskite nanomaterials with desired optoelectronic properties and minimal deleterious defects, thereby rendering their use in a gamut of optoelectronic devices with improved performance.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.