Direct Optical and Thermal Lithography of Inorganic Nanomaterials for Optics and Optoelectronics

This thesis delves into chemical techniques for the direct optical patterning of colloidal nanomaterials. Chapter 1 outlines colloidal nanomaterials, their applications in devices, and the need for innovative patterning methods, leading to the development of Direct Optical Lithography of Functional Inorganic Nanomaterials (DOLFIN).Chapter 2 establishes a library of photosensitive ligands and additives for DOLFIN. We demonstrate their use in patterning various nanocrystals (NCs) and study their photodecomposition pathways and their impact on NC solubility. In Chapter 3, we discuss ligand-crosslinkers for forming a crosslinked QD network. This network binds adjacent QDs, increasing film resistance to dissolution. The type and amount of crosslinkers play a crucial role in the process. The ligand crosslinking involves two steps: radical formation followed by either C–H insertion or alkene addition reactions. Chapter 4 introduces thermally sensitive ligands for patterning diverse functional inorganic nanomaterials. The direct Heat-Induced Patterning of Inorganic Nanomaterials (HIPIN) method is presented, capable of patterning various NCs using different heat sources and lasers. We utilize volatile amine ligands, thermally responsive ammonium carbamates (ACMs), and N-(tert-butoxycarbonyl)-l-cysteine methyl ester (CME) ligands for this purpose. In Chapter 5, we apply DOLFIN techniques to optics and optoelectronics fabrication. First, we introduce a photoresist-free, high-resolution optical patterning method for quantum dot (QD) LEDs using photoacid generators. This method produces uniform QD electroluminescence patterns with features as small as 1.5 μm, preserving the QDs' properties. This approach can advance QD-based displays and other optoelectronic devices. Second, we develop two direct lithography methods to create dielectric and semiconducting NC waveguides. By leveraging direct laser writing, we fabricate consistent beam splitters and adjustable nanoparticle micro-ring resonators.