Tailoring Terahertz Emission in Ultrafast Multi-Functional Devices using Reduced-Dimensional Hybrid Metal Perovskites

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Nontechnical: Terahertz technologies hold great promise for future computing and communications. Energy-efficient and miniaturized THz sources using light-weight, low-cost, and robust materials are a long sought goal. Few materials, however, possess the attributes needed to realize working devices. Metal halide perovskites with reduced dimensionality are a new class of semiconductors with great promise for such applications. They can be inexpensively synthesized and solution processed, have attractive electronic properties, and tolerate defects. These properties have led to great interest for applications in solar cells and flexible displays. Perovskites also show promise as high performance THz sources. Remarkably, these properties can be controlled via spin electronics (spintronics) that exploit the fundamental properties of electrons in devices. This makes it possible to interface perovskites with magnetic materials, enabling spintronic THz emitters. This project will lead to low-cost and energy-efficient THz devices with complementary magnetic, optical and electronic functions. The PIs will educate graduate and undergraduate students, including those from underrepresented groups, by integrating research with education. Established and developing outreach programs will be used to involve K-12 students with the project.Technical:This project focuses on the realization of a spintronic control of the broadband THz emission in RD-HMH/Ferromagnet heterostructures. The research consists of three research thrusts: (1) Demonstrate the proof-of-concept spintronic hybrid THz emitter using reduced dimensional-hybrid metal halide (RD-HMH) polycrystalline thin films prepared by a low-cost spin-coating approach, taking advantage of the fast relaxation of spin (akin to a switch) and efficient spin-to-charge interconversion thanks to the heavy metal elements in RD-HMHs. A thorough, fundamental physical understanding of the ultrafast generation of THz emission in RD-HMH/Ferromagnet heterostructures will be unraveled. (2) Tailor the THz emission via engineering RD-HMH single crystals. Wafer-scale single crystals-based THz emitters will be designed and optimized with tunable bandwidth as well as high quality (Q-) factors, in complement to that of polycrystalline-film emitters. (3) Optimize the THz emission via versatile chemical synthetic routes using device building blocks. The available pool of high-quality synthesized RD-HMH candidates with tunable quantum-well effects are ready to be fabricated into efficient THz emitters, allowing the spintronic and magnetic control of THz generation that can be potentially used for logic applications utilizing THz-wave emission and absorption.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.