In order to fabricate layered electrochromic devices capable of reversibly changing color in response to applied voltage, pulsed laser deposition was used to deposit thin films of tungsten oxide on fluorine doped tin oxide substrates.The thin films were deposited at room temperature in an O2 atmosphere of the order of 10−1 mbar on FTO/glass substrates using a KrF pulsed laser source. XRD analysis confirmed the resulting films to be amorphous and UV-Vis spectroscopy confirmed transparency. Raman shift confirms non-crystalline WO3 presence. Electrochromic devices were connected to a cyclic voltammetry system to regulate voltage sweeps, investigate charge transport, response time and reversibility of color/bleached states. Scanning electron microscopy was performed on the films post device operation to examine the surface topography and composition. Raman spectroscopy and XRD was performed post device films to investigate any changes in the films. Li+ ion conducting glasses of composition xLi2SO4 - (1-x)[0.50Li2O-0.5(2NH4H2PO2)) were characterized using resistivity measurements and neutron diffraction experiments to evaluate them as suitable substitutes for the electrolyte in the electrochromic devices. Formation of crystallites above 400°C has been observed which is understood to hamper Li+ ion mobility, resulting in reduced performance of the electrolyte. The acid based electrochromic devices have exhibited superior reversibility.

The goal of this work was to fabricate electrochromic devices made with pulsed laser deposited tungsten oxide films and evaluate the effects of material properties on device performance. The oxide films were deposited in O2 atmospheres from 10-3 - 10-1 mbar on ITO/glass substrates between room temperature (RT) and 450 °C. A pulsed KrF laser operating at 248 nm was used to ablate the WO3 target. XRD analysis showed amorphous native films for RT depositions and orthorhombic poly-crystalline films deposited at 450 °C. UV-Vis spectroscopy showed transparent films deposited at 10-1 mbar and opaque films for lower chamber pressures. For depositions at RT, atomic force microscopy revealed ultra-smooth surfaces for films deposited at 10-2 mbar and disordered/porous surface morphology for films deposited at 10-1 mbar. With the substrate temperature at 450 °C, the topography had visible grain patterns. IV measurements were done on films grown at different chamber pressures. Preliminary devices were constructed by sandwiching a drop of 2.0-M HCl between the oxide/ITO/glass and a top ITO/glass electrode. Cyclic voltammetry was used to automate the bias potential, determine charge insertion, and investigate response time and the effects of repeated cycles. Devices constructed with opaque oxygen-deficient or poly-crystalline tungsten oxide films displayed poor electrochromism while devices constructed with transparent amorphous WO3 films (deposited at 10-1 mbar and RT) exhibited electrochromic properties including a large optical modulation (76.1 %T at 705 nm) and a coloration efficiency of 11 cm2/C.

The preparation and characterization of thin film oxides and chalcogenides by pulsed laser deposition (PLD) is presented. An overview of fundamental PLD concepts are presented and are followed by a description implementation and development of the PLD systems at OSU. We present the results of thin film growth of high electron mobility In2O3:W in which we have prepared films exhibiting □ > 100 cm2/Vs on vitreous SiO2 substrates. The growth of Cu3TaQ 4 (Q = S, Se) films is outlined as a two step process consisting of PLD of ceramic targets followed by ex-situ annealing in chalcogenide vapor. Also, BiCuOSe thin films have been prepared in-situ and exhibit a high hole mobility up to 4 cm2/Vs. A discussion of their electronic structure is presented which explains the nature of the low band gap energy on the basis of deep Bi 6p level at the conduction band minimum. Finally, the results of BaBiO3 thin film preparation are presented in which both polycrystalline and highly (00l) oriented samples were grown.

Investigates the structural and mechanical properties of pulsed laser deposited (PLD) titania (TiO2) thin films. Uses nano-indentation to determine the mechanical properties of the films as a function of the growth parameters.

Oxides form a broad subject area of research and technology development which encompasses different disciplines such as materials science, solid state chemistry, physics etc. The aim of this book is to demonstrate the interplay of these fields and to provide an introduction to the techniques and methodologies involving film growth, characterization and device processing. The literature in this field is thus fairly scattered in different research journals covering one or the other aspect of the specific activity. This situation calls for a book that will consolidate this information and thus enable a beginner as well as an expert to get an overall perspective of the field, its foundations, and its projected progress.

Pulsed laser deposition (PLD) is a promising technique for creating inexpensive, nanostructured thin films which may lead to structures suitable for photocatalysis. During this study, multiple tungsten oxide thin films were prepared using two types of PLD techniques. The first method was conducted at US Photonics, Springfield, MO, using a femtosecond laser while the second method relied on use of an excimer (nanosecond) laser located at Missouri State University. Films were first deposited on glass using both methods at room temperature. Further study was conducted on thin films deposited on sapphire and silicon deposited at room temperatures and at elevated temperatures. In addition to using two types of PLD, an investigation of the properties of tungsten oxide thin films incorporated with alkali metals was conducted. This was achieved by preparing a target using tungsten oxide with small amounts of sodium nitrate (NaNO3). The addition of alkali metals has been known to change the structure as well as the electrical, chemical, and physical properties of the bulk material. After deposition, the thin films were annealed at 450°C up to 30 hours in air. Characterization of the films’ structure and morphology were made using scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) both before and after annealing. Characterization of the films allowed me to determine which method of PLD as well as which substrate (glass, silicon, or sapphire) is more suitable for growing thin films suitable for photocatalysis applications.