UC Berkeley

In recent years, there has been significant attention drawn towards metal halide perovskites, aclass of semiconducting materials distinguished by their remarkable optoelectronic properties. In the halide perovskite structure, the metal halide octahedron ([BX6]n-, B = metal cation, X = halide anion) is the fundamental building block and functional unit. This dissertation aims to present a novel perspective by proposing a supramolecular approach to manipulate the metal halide octahedral building blocks. The new supramolecular building block is constructed from the ionic halide perovskite octahedral unit and crown ether supramolecular cations, resulting in the formation of a novel (crown-ether@A)2BX6 (A = alkali metal cation) dumbbell structural unit. The chemistry, properties, and application of this supramolecular approach constitute the main topics of this dissertation. Chapter 1 provides an overview of halide perovskite materials, encompassing their structure, synthesis, properties, and applications. The concept of dimensionality in halide perovskites and the significance of the metal halide octahedral [BX6]n- building blocks are introduced, laying the foundation for the subsequent discussion on the supramolecular assembly approach. In Chapter 2, we delve into the details of the supramolecular assembly approach, highlighting its structural and compositional adaptability, along with its immense potential in various optoelectronic applications. Chapter 3 delves into the synthesis and characterization of two new blue and green emitters with near-unity photoluminescence quantum yield (PLQY), (18- Crown-6@K)2HfBr6 and (18-Crown-6@K)2ZrCl4Br2, derived from the supramolecular assembly approach. Comprehensive optical studies of these materials are presented, along with demonstrations of their applications in display and 3D-printing technologies. Lastly, chapter 4 provides a summary of the research findings and offers insights into the future directions for the supramolecular assembly approach, establishing a solid foundation for the future development and application of halide perovskites.