Over the last decade, impressive development in lead halide perovskites (LHPs) have made them leading candidate materials for photovoltaics (PVs), X-ray scintillators, and light-emitting diodes (LEDs). The success of LHPs NCs in lighting and display applications is mainly originated from their high photoluminescence quantum yield (PLQY), narrow emission, sizable bandgap, and cost-effective fabrication. Consequently, a comprehensive understanding of the design principles of LHP NCs will fuel further innovations in their optoelectronic applications. This dissertation centers on the synthesis and self-assembly of LHP NCs. At first, we investigate the capability of colloidal synthetic routine to engineer the shape, size, and dimensionality of the resulting LHPs NCs (chapter 2), including 0D nanospheres, 2D nanoplates, and 3D nanocubes. Starting from the LHPs NCs, nanoplates (chapter 3), nanowires (chapter 4), and superstructures (chapter 5) are successfully achieved via various self-assembly strategies. In chapter 3, we present a liquid-air interfaces-assisted self-assembly technique to obtain micro-scale CsPbBr3 nanoplates from as-synthesized nanoscale NCs. The AC-HRTEM offered an atomic-level observation during the structural evolution and revealed an oriented attachment-mediated assembly mechanism. The assembled CsPbBr3 nanoplates exhibited ultrahigh stability under X-ray energy dispersive spectroscopy (EDS) mapping conditions (300-kV electron beam), and the first atomic-resolution EDS elemental mapping data of LHP NCs were acquired. In chapter 4, we demonstrate an efficient green-chemistry approach for the self-assembly of CsPbBr3 NCs into 1D nanowires and nanobelts via the light induction. As an elegant and promising green-chemistry approach, light-induced self-assembly represents a rational method for designing perovskites. In chapter 5, we will explore the self-assembly of CsPbBr3 NCs into superstructures to overcome the ‘green gap’ to achieve a pure green emission with high PLQY for realizing next-generation vivid displays. In summary, we systematically investigated the mechanisms of LHP NC self-assembly, the kinetics of their morphological evolution and phase transitions, and driving forces that govern the self-assembly process. The assembled LHP NCs manifest desirable properties (e.g., superfluorescence, improved photoluminescence lifetime, enhanced stability against moisture, light, electron-beam irradiation, and thermal-degradation) that translate into dramatic improvements in device performance.

Collagen I, a natural protein found in animal tissues, can self-assemble into fibrous matrices that support cell and tissue growth. Peptide mimics of collagen are able to recapitulate this selfassembly process towards the development of biomaterials for tissue engineering. In recent years, the metal mediated self-assembly of collagen mimetic peptides (CMPs) has allowed access to various particle morphologies. Herein, two studies are presented. In the first, NCOH-FOGER, a cell adhesive CMP capable of metal-triggered self-assembly, was utilized to develop a model system to mimic natural collagen’s interactions with endothelial cells. Notably, a cobalt(III)- NCoH-FOGER assembly was able to induce endothelial cells to form network-like structures. In the second, a CMP was modified to include an unnatural amino acid, L-4-trans-fluoroproline, which increased the thermostability of its folded state. The effect of this substitution on the morphology of self-assembled particles was evaluated.

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Nanoparticles are regarded as exciting new building blocks for functional materials due to their fascinating physical properties because of the nano-confinement. Organizing nanoparticles into ordered hierarchical structures are highly desired for constructing novel optical and electrical artificial materials that are different from their isolated state or thermodynamics random ensembles. My research integrates the surface chemistry of nanoparticles, interfacial assembly and lithography techniques to construct nanoparticle based functional structures. We designed and synthesized tailor-made ligands for gold, semiconductor and magnetic nanoparticle, to modulate the assembly process and collective properties of the assembled structures, by controlling the key parameters such as particle-interface interaction, dielectric environments and inter-particle coupling etc. Top-down technologies such as micro contact printing, photolithography and nanoimprint lithography are used to guide the assembly into arbitrarily predesigned structures for potential device applications.

Molecular simulations are computer experiments that allow us to investigate thermodynamic and transport properties of complex chemical systems. Here, we have investigated self-assembly of organogelators and analysed the diffusion characteristics of small molecules in the nanopores of zeolites. Molecular gels are attractive soft-materials with viscoelastic properties with applications in drug delivery, tissue engineering, sensing, etc. Small organic amphiphilic gelators act as a building block of complex 3-dimensional network in molecular gels. Due to time and length scale differences, the understanding and characterization of early stage aggregation of gelators is difficult using experimental techniques. Classical and quantum mechanical approaches have been used to understand the self-assembly of gelator molecules and to rationalize the gelation. We have used density functional theory (DFT) to derive new quantity namely, pseudo-cohesive energy density to rationalize the gelation of di-Fmoc-L-lysine. Molecular dynamics is used to probe the self-assembly and conformation of gelators in DMSO-water. We have also studied the self-assembly of 12-hydroxyoctadecanamide in octane. We used DFT to calculate the dimer energy in the vacuum and meta-dynamics simulation to calculate potential of mean force in the condensed phase. Interestingly, we found that, dimer energetics was not sufficient to elucidate bulk aggregation behavior, such as, probability distribution of different dimers in aggregation. We also observed different types of branched and mesh-like networks in the aggregation, which are analogous to the network found through experimental imaging techniques. Zeolites are crystalline materials with well defined nanoporous channels and act as molecular sieves. They are attractive for catalytic applications due to their tunable Bronsted and Lewis acidity. A wide array of zeolite polymorph offers versatile micro and meso-porous channels to accommodate small molecules like glucose to big and complex lignocellulose molecules for undergoing chemical transformations. In this current study, we present the transport properties of -glucose into Faujisite zeolite framework. We have investigated the trajectory of the glucose molecule into porous material and found that, the diffusivity of glucose inside zeolite pore is two order of magnitude smaller than that of bulk solutions. We have also observed the variable loading rate of glucose molecule inside pore at different temperatures.