UC San Diego

As an emerging class of semiconductors, metal halide perovskites have demonstrated tremendous potential in various applications, including photovoltaic solar cells, light-emitting diodes, photodetection, and many other electronic devices. While most of these perovskite electronic devices have adopted polycrystalline perovskite thin films, problems of polycrystalline thin films like the high density of grain boundaries and defects, low stability can hinder the further performance enhancement of perovskite electronic devices. Comparing with their polycrystalline counterpart, single-crystal perovskites provide opportunities in solving such problems. Not only can they provide enhanced crystalline quality and excellent material stability, but also the possibility to alter the electronic properties of perovskites by lattice-mismatch-induced strain. Yet the development of single-crystal perovskite electronic devices is still in its infancy due to the low controllability over the growth of single-crystal perovskite nano/micro-structures and the incompatibility with the conventional semiconductor fabrication protocol.

This research aims to develop a platform for growing high-quality single-crystal metal halide perovskite nano/micro-structures using controllable chemical homo/heteroepitaxial growth and fabricating high-performance single-crystal-perovskite-based electronic devices with the conventional semiconductor fabrication protocols. In Chapter One, the basic properties of metal halide perovskites and the current problems presented in the polycrystalline perovskite thin films will be introduced and discussed. In Chapter Two, controllable homoepitaxial growth of metal halide perovskite micro-arrays will be introduced. Our work presents the first controllable growth of large-area single-crystal perovskite microarrays with different sizes, morphologies, crystalline orientations, and patterned structures. In Chapter Three, controllable strain engineering of single-crystal metal halide perovskite thin films by heteroepitaxial-growth-induced lattice mismatch will be introduced. Our work presents the first controllable strain engineering in metal halide perovskite family. In Chapter Four, epitaxial stabilization induced by the chemically epitaxial strain growth will be introduced. Our strategy provides insights into structurally stabilizing the metastable metal halide perovskite family. Our understanding of the controllable epitaxial growth of metal halide perovskites paves the way for next-generation single-crystal metal halide perovskites electronic devices.