The idea that structure determines the properties of a material is a powerful concept in chemistry and in all fields in which chemistry is important, including engineering, medicine, and materials science. My research aims to better understand the structure-property relationships of a class of materials known as metal–organic frameworks (MOFs)....
Electrochemical devices play a vital role in the efforts towards a sustainable green future. Solid acid based electrochemical cells, employing super protonic CsH2PO4 (CDP) as the electrolyte component, offer unique application advantages due to their operability at intermediate temperatures 250°C. At these temperatures, one can achieve improved reaction kinetics over...
Thermoelectric devices utilize semiconducting n-type and p-type thermoelectric materials to convert heat into electricity. Despite their promise for deep space power generation or waste heat recovery, most high-performing thermoelectric materials reported in literature are absent in practical applications - partially due to inconsistent synthesis and poor mechanical performance. This work...
A significant portion of material science research is concerned with understanding theway that defects affect the properties materials. In the field of thermoelectrics introducingor removing point (0D), dislocation (1D), grain boundary (2D), or precipitate (3D) defectsare popular methods for altering a materials thermoelectric efficiency. Herein I discussdifferent studies conducted during...
Industrial processes heavily rely on catalysts to control product selectivity and lower energy barriers required for chemical transformations. Catalysts are most commonly solid heterogeneous catalysts that facilitate separations from reaction mixtures and enhance recyclability. Heterogeneous catalysts used in industrial processes exhibit efficacious results, but in certain instances drawing structure-function relationships...
To relate the mechanical responses of hard-soft copolymer systems with their microstructures, a coarse-grained molecular dynamics (CGMD) approach is employed. With the generic bead-spring polymer model mapped from atomistic simulations, this dissertation first studies the morphology of structures with various hard-soft compositions and interactions between hard beads. Following that, this...
The start of the 21st century brought the sweeping proliferation of portable electronics such as laptops, tablets, and smartphones. These technologies were largely enabled by advances in energy storage methods – lithium ion batteries in particular. Society's push for more advanced energy storage applications, such as electric vehicles, stresses the...
Transition metal oxides (TMOs) like perovskites are known to be versatile for functional properties such as ferroelectricity, magnetism, optical properties, and high-temperature superconductivity, because of their sensitive coupling between atomic structure and properties. By studying and understanding the fundamental structure-property relationships present in TMOs, it is possible to strategically engineer...
Continuous and coordinated materials discovery efforts have amassed a wealth of knowledge concerning many general classes of materials. The number of known phases of all structure-types, however, is far less than number of possible materials dictated by the elements on the periodic table. Recently, with improved computational abilities and well-developed...
Thermoelectric (TE) materials has been drawn broad attention given that it can enable direct conversion between thermal and electrical energies, hence is treated as a vital candidate for clean power generation as well as waste heat recycling. However, the energy conversion efficiency of TE devices used nowadays is still very...
Van der Waals, or layered, materials offer a flexible platform to tune properties via exfoliation down to the single- or few-layer limit; they are at the forefront of cutting-edge materials science and engineering research because of the innumerable ways to tune materials as a function of thickness or composition. Due...
Two-dimensional (2D) materials are a promising class of electronic materials that have generated great interest to improve and create new and existing technologies. The promise of this family of materials relies on their high surface-to-volume ratio and atomic thickness in addition to their unique (opto)electric properties. However, these morphological properties...
As the interest in rational synthesis for solid-state materials accelerates, there is an urgent need to understand the design principles concealed within these reactions. In situ material synthesis provides such an avenue to not only uncover these assembling rules, but also for finding new materials even in seemingly familiar phase...
In the United States and around the world, the growing energy demands and climate concerns necessitate renewable and efficient energy production. Thermoelectric materials could be one small part of this larger picture movement, but their high cost and low efficiency must be improved to realize commercial use. To decrease the...
Part I: Evaluating the relationship between Crosslink Kinetics and Thermodynamics with the hydrogel mechanics. The past two decades have witnessed a surge of applications built upon dynamic covalent chemistry (DCC), both attributed to the scope of developed reactions as well as their modularity.1-3 These reactions have comparable strengths to their...
Drying oils have been used as a binding medium for oil paints since the 15th century. These oil paints transition from a liquid-like paste to a solid-like film as a result of crosslinks forming between the oil molecules. These reactions have been extensively studied chemically, but other material properties are...
Supervised learning model is one of the most fundamental machine learning models. It can provide powerful capability of prediction by learning complex patterns hidden in many, sometimes thousands, predictors. It can also be used as a building block of other machine learning tasks, like unsupervised learning and reinforcement learning. Such...
Nanocarriers are drug delivery vehicles that have at least one dimension at the nanoscale (10-9 m). Engineering the nanocarrier surface is a strategy for targeting drug delivery to specific cell types to enhance efficacy and minimize side effects. A useful analogy is to consider how the chassis of an automotive...
Nanomaterials are increasingly incorporated in modern day life, from the biogenic viruses that cause pandemics and the mineral crystallites embedded alongside collagen in our bones, to the anthropogenic nanomaterials that are small but powerful components of sunscreen and paint, swimming pool algaecides and wound dressings, cancer treatments, bicycle frames, and...
Selecting the best material to deliver optimum performance in real-world applications is one of the most significant challenges in engineering. Hundreds of thousands of computationally-predicted, but experimentally unexplored materials exist today in the public inorganic material databases as candidates for consideration. This thesis discusses three projects in the domain of...
Metallic conductivity and broken inversion symmetry were long thought to be contraindicated properties, under the assumption that long-range Coulombic interactions (screened by free charge carriers) were necessary for coordinated polar displacements. Within the past decade, the discovery of polar metals has prompted a rethinking of the relationship between metallicity and...
Thermoelectric materials have attracted widespread attention in recent decades because of their ability to directly convert thermal energy into electrical energy. Given that waste heat is the primary source of lost energy in the world, the implications of developing better thermoelectric materials are both immediate and far-reaching. Admittedly, large progress...
Dual-phase (DP) steels have been widely applied in automobile industry, and are famous for continuous yielding in their corresponding stress-strain curves. The appearance of yield-point phenomena, or discontinuous yielding, is considered undesirable for DP steels. Herein, we take advantage of the undesirable appearance of yield-point phenomena in DP steels as...
This thesis describes the synthesis and photophysical characterization of low-dimensionalmaterials—including thin-film semiconductors, colloidal quantum dots, and molecules—with the
broader motivation of integrating them into mixed-dimensional heterostructures with novel
responses to external stimuli. Due to their high surface area to volume ratio and incomplete
dielectric screening, mixed-dimensional heterostructures have high sensitivity...
Soft materials such as colloids and polymers often exhibit a variety of mesoscopic structures that are governed merely by weak physical interactions. Due to these intermediate structures, they can be easily taken out of thermal equilibrium by introducing external stimuli such as a shear flow and electromagnetic fields. This thesis...
Increasingly high global energy consumption demands effective approaches to high energy efficiency and, at the same time, paths to reduced release of carbon dioxide, a primary greenhouse gas behind global climate change. Friction reduction is a vital aspect towards making energy systems more efficient and one of the most crucial...
One of the grand challenges in science is development of soft materials that mimic living organisms to optimize the way we use energy, translate or morph reversibly or sense their envi- ronment and respond in a useful fashion. Using the insights from studying biological structures, we hope to design soft...
From the early usage of metallic thin films as mirrors tracing back to 2900 BC, to the modern thin film photonic circuits as a mature optical processing platform, and to the growing class of atomically-thin two-dimensional (2D) materials with diverse and tailorable properties, thin film materials have played an important...
Recent progress in semiconductor synthesis and photophysics has revealed a host of new materials with exciting properties for applications in optoelectronic devices such as sensors, photovoltaics, solid state lighting, and more. One of the most significant recent additions to the field is the class of hybrid and inorganic materials that...
Herein, we present an overview of our studies of the morphology, dynamics, and formation of heterogeneous soft matter systems via the emerging technique of liquid phase transmission electron microscopy (LPTEM). This particular subset of materials, more commonly referred to as emulsions, is tremendously commercially and biologically relevant, encompassing applications in...
The investigation of ceria-related materials has a long history since 1920s. The first publication on web of science traces back to 1928. Ever since that, more studies come out and surge starting from 1987. This material has attracted extensive attention due to its wide applications in electrochemical devices, catalysis, and...
Biological organisms have the extraordinary ability to form mineral structures with unparalleled control. From curved single crystals to hierarchically structured skeletal parts, biomineralization processes produce materials with properties that are highly optimized for their intended applications. These processing techniques occur at ambient conditions using materials abundant in the environment, and...
The on-going demand for miniaturized optical and on-chip photonic systems of the future has led to a few potential solutions in the literature. Recent advances in van der Waals and 2-dimensional materials signal a bright future for the next generation, compact electronic and photonic devices. With reduced dimensionality and material...
The ability to control the crystalline ordering and morphology of polymeric nanomaterials is a grand challenge in the field of materials science, which could enable the development of functional materials able to solve long-standing problems in renewable energy and medicine. In this work, we explore a combination of supramolecular chemistry...
Nanomaterials present an exciting landscape of innovation at length scales below 100 nm, wherein controllable synthesis and materials metrology have led to tunable structure-property relationships and next-generation products. The disruptive field of nanotechnology is poised to capitalize upon the exotic chemistry and physics of these nanomaterials to enable more efficient...
Multimetallic nanoparticles represent an important class of electrocatalysts which are critical for many energy and environmental applications including fuel cells, hydrogen production, and greenhouse gas elimination. The properties of these nanoparticles depend on their composition, size, shape, and structure. Therefore, developing new strategies which provide a high level of control...
Tooth enamel, the outermost layer of human teeth, is a complex, hierarchically structured biocomposite. The details of this structure are important in multiple human health contexts, from understanding the progression of dental caries (tooth decay) to understanding the process of amelogenesis (enamel formation) and related developmental defects.While much is known...
In this dissertation, I summarize my findings of the dynamics of colloidal suspensions over a large range of volume fractions in two systems: drop impact and film rupture. The existence of a deformable surface in both these systems allows me to capture the consequences of non-Newtonian flow using high-speed imaging....
Advanced wireless soft electronics integrate a wireless power transfer circuit and a small battery. It is skin-compliant, and lightweight accommodating the complex motion of the body. These unique features of the device provide a continuous physiological measurement without discomfort and spatial constraints. Using the device, we can observe and track...
Atomistic methods offer a powerful set of tools in the study of materials systems, as they allow materials scientists to ask questions with a high degree of specificity. They are well suited for studying and designing energy materials, critical due to the climate crisis, in part due to their ability...
As the pursuit for higher performance and lower cost photovoltaics, and for new applications of optoelectronic devices moves beyond crystalline silicon, there are many unique opportunities for materials research into hybrid organic-inorganic, and organic semiconductors. This dissertation focuses on both hybrid organic-inorganic materials and organic materials for optoelectronic applications. In...
Ultrafine particles are often used as lubricant additives because they can enter tribological contacts to reduce friction and protect surfaces from wear. They tend to be more stable than molecular additives under high thermal and mechanical stresses during rubbing. However, in lubricant oil, ultrafine particles tend to aggregate together to...
Semiconductor nanocrystals possess unique photophysical properties that make them desirable for many optoelectronic applications such as photovoltaics, LEDs, and quantum computing. When the size of a semiconductor is reduced to below the excitonic Bohr radius of the material, its carriers becomes quantum confined resulting in drastic changes to optical, electronic,...
Early-stage oxidation and corrosion mechanisms of CoCrMo and NiCrMo alloys can be analyzed on the nanoscale by transmission electron microscopy. Both alloys are attractive for a broad array of applications such gas turbines and aircraft engine components as they are known for their excellent corrosion resistance and mechanical properties at...
The halide perovskites AMX3 (A = large cation, B = Sn or Pb, and X = halide) have been the subject of intense investigation due to their outstanding optical and electronic properties, which have enabled high solar cell efficiencies thanks to a beneficial electronic structure and long charge carrier lifetimes....
How molecular chirality manifests at the nano- to macroscale has been a scientific puzzle since Louis Pasteur discovered biochirality. In general, amphiphilic molecules can organize into a variety of assembly shapes including micelles, spherical vesicles, cylindrical micelles, and planar bilayers. However, when such amphiphilic molecules are chiral, helical ribbons, helicoidal...
This thesis explores the potential of two-dimensional (2D) or van der Waals (vdW) materials for printed optoelectronic devices. The research focuses on the development of processing, imaging, and modeling of materials and thin-film devices to optimize performance and introduce novel properties. A gate-dependent resistor network model is presented that establishes...
The three-dimensional (3D) nanoscale structure of III-As nanowires is correlated with optical and electronic property measurements to deconvolve the contributions of strain, composition, and crystal structure to characteristics of interest for future electronic and optoelectronic devices. Multiple advanced two-dimensional (2D) and 3D characterization techniques are employed such as atom probe...
Advancements in the understanding and synthesis of transition metal compounds have allowed materials engineers to design functional materials with a range of properties, such as ferroelectricity, non-linear optical activity, colossal magnetoresistance, and superconductivity. Conventional routes to tune and design functional materials includes chemical cation substitution and heterostructuring of oxide thin...
Rationally assembled nanostructures exhibit distinct physical and chemical properties beyond their individual units. The development of nanofabrication tools enables precise structural defining of nanomaterials scalable to large areas. This dissertation focuses on plasmonic nanoparticle arrays that show unique diffractive coupling with lattice spacings engineered close to the wavelength of light....