Repurposing low-dimensional hybrid perovskites for the detection of low-energy photons

金属卤化物钙钛矿是一类新型溶液可加工半导体。这些是混合材料，使用各种有机和无机成分作为构建块。这允许调整其光学，电学和热输运性质，以满足所需的用途。它们在太阳能收集、显示器和固态照明等应用中表现出了特别的前景。这个项目的重点是了解一类金属卤化物钙钛矿的基本性质。这些二维（2D）材料由设计排列的相互穿透的有机和无机层组成。该团队将研究二维钙钛矿的结构和光学性质，以深入了解是什么控制了它们的导热性，以及电荷载流子如何与晶格相互作用。了解二维钙钛矿的独特性质将有助于评估其在设备应用中的潜力，并加速其在先进设备技术中的应用。特别是，目标是建立用于检测红外led的二维钙钛矿，而红外led传统上依赖于气相生长的半导体，其加工成本很高。该项目将培训研究生和本科生合成和表征新型半导体，包括构建和修改仪器。技术描述检测光的能力在从摄影和生物成像到材料表征和精密计量等领域至关重要。光探测的难度取决于每个光子所携带的能量，光子是光的最小能量量子。虽然硅基探测器是成熟和敏感的，但探测能量低于硅带隙的光子通常更具挑战性。该项目的目标是了解二维金属卤化物钙钛矿的导热性和激子-晶格相互作用如何通过有机间隔物的类型、有意引入的堆叠紊乱以及无机八面体层的连接模式来影响和最终控制。各种技术，包括时间分辨振动泵浦可见探针光谱，泵浦探针光学成像和同步加速器x射线衍射，将被用来表征明智选择的二维钙钛矿成分的结构-性质关系。所获得的理解将提供对这些溶液可加工材料的热学和光学性质的基本理解，并建立知识库，将它们用于检测近红外到中红外范围内的低能光子。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。

Nontechnical DescriptionMetal halide perovskites are a new class of solution-processible semiconductors. These are hybrid materials, using a variety of organic and inorganic components as building blocks. This allows tuning of their optical, electrical and thermal-transport properties for the desired use. They have shown particular promise for use in applications such as solar energy harvesting, displays, and solid-state lighting. This project focuses on understanding the fundamental properties of a sub-class of metal halide perovskites. These two-dimensional (2D) materials consist of interpenetrating organic and inorganic layers arranged by design. The team will study the structure and optical properties of 2D perovskites to gain insight into what governs their thermal conductivity and how charge carriers interact with the crystal lattice. Understanding the unique properties of 2D perovskites will help to evaluate their potential for device applications and accelerate their adoption into advanced device technologies. In particular, the goal is to establish 2D perovskites for detection of infrared led, which has traditionally relied on vapor-phase grown semiconductors that are expensive to process. The project will train graduate and undergraduate students in synthesis and characterization of novel semiconductors, including building and modifying instrumentation.Technical DescriptionThe ability to detect light is crucial in areas ranging from photography and bio-imaging to materials characterization and precision metrology. The difficulty of light detection depends on the energy carried by each photon, the smallest energy quanta of light. While silicon-based detectors are mature and sensitive, the detection of photons whose energies fall below the bandgap of silicon is generally more challenging. The goal of this project is to understand how the thermal conductivity and exciton-lattice interactions of two-dimensional metal halide perovskites can be influenced and ultimately controlled through the type of organic spacers, the intentionally introduced stacking disorders, and the connectivity mode of the inorganic octahedral layers. A variety of techniques, including time-resolved vibrational-pump visible-probe spectroscopy, pump-probe optical imaging, and synchrotron x-ray diffraction, will be employed to characterize the structure-property relationships of judiciously chosen two-dimensional perovskite compositions. The understanding gained will provide a fundamental understanding of the thermal and optical properties of these solution-processable materials and establish the knowledge base to use them for detecting low-energy photons in the near-infrared to the mid-infrared 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.