Tin-doped indium oxide (ITO) has been widely used for various optoelectronic devices such as display panels, light-emitting diodes and solar cells due to its unique optical and electrical properties. Thin ITO films can be fabricated by a number of methods such as molecular beam epitaxy (MBE), laser ablation, dc sputtering, e-beam deposition, vapor phase deposition, electrochemical deposition and hydrothermal method. Apart from the conventional thin film form, one dimensional ITO nanorods or nanowires are attracting much research interest due to their high aspect ratio and large surface to volume ratio. For instance, a network made of ITO nanowires can exhibit high transparency (over 95 %) and high flexibility without losing its conducting property as reported recently. This network can be potentially used for flexible photovoltaic devices. In this study, ITO nanorods or nanowires were fabricated using the vapor deposition, dc sputtering and e-beam deposition. The use of short ITO nanorods (100 nm) on glass and commercial ITO substrates as bottom electrodes improving the charge collection of bulk heterojunction organic solar cells had been demonstrated. The morphology of the ITO nanostructures was studied by scanning electron microscope (SEM) and transmission electron microscope (TEM). The crystal structure and growth direction were studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED), respectively. Optical properties were examined using transmission and photoluminescence measurements. The performance of the organic solar cells was examined using the I-V characteristics and external quantum efficiency (EQE) measurements. The growth mechanism of the ITO nanowires using different fabrication methods was discussed. The effects of the substrate temperature, oxygen content, choice of substrate and evaporation rate on the morphology, transmittance and sheet resistivity were investigated. When short ITO nanorods were incorporated into the bulk heterojunction organic solar cells, a significant improvement of the power conversion efficiency (PCE) was observed. The higher efficiency of the studied solar cells was attributed to the improved charge collection. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Geography and Geology / Master / Master of Philosophy

Indium-tin oxide (ITO) is commonly used as the transparent electrode in organic photovoltaic (OPV) devices. ITO's transparent properties come at the expense of less than ideal electrode characteristics arising from insulating over-oxidized surface species. OPVs fabricated on the native ITO surface tend to exhibit poor performance with a high degree of variability from device to device. Aggressive acid etching of the ITO surface removes the majority of the insulating surface species leading to improvements in OPV efficiency with greater reproducibility and increased device to device consistency.Organic light emitting diodes (OLEDs) are planar electroluminescent light sources that naturally couple a portion of their emission into internally reflected modes within the device substrate. Although this coupling property is well known, few attempts have been made to integrate OLEDs as light sources for internal reflection elements. Furthermore, OPVs share the optical coupling properties of OLEDs and therefore can be used as integrated internal reflection detectors. Integrating both an OLED light source and an OPV detector onto the same substrate results in an internal reflection sensing platform that requires no free-space optics, has low power consumption requirements, and can be easily fabricated on substrates occupying an area less than one square inch. In this work we establish a functional prototype design, characterize the fundamental coupling properties, and demonstrate several surface sensing responses of this fully integrated optical sensing platform.The net solar power production from OPVs arises from the interactions between multiple currents through the device. The photocurrent is the only power producing current in the device and understanding the voltage dependent nature of this current is essential in OPV research. Analysis methods of conventional, inorganic photovoltaics do not adequately describe the photocurrent behavior commonly observed in OPVs. OPV analysis is therefore somewhat limited by the methods commonly employed. To improve upon the convention methods we develop a simplified method of OPV photocurrent analysis based on electrochemical methods that accurately describes the voltage dependence of the photocurrent and leads to greater insight into the key parameters involved in solar power production from OPVs.

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No description available.

This Thesis describes the synthesis, structural characterization and properties of some tin(II) and tin(IV) compounds containing bidentate ligands. Chapter 1 describes the main spectroscopic techniques used in the identification of tin(II) compounds; infra-red, ¹¹⁹Sn Mössbauer and n.m.r spectroscopy are outlined, and relevant examples given. A comprehensive listing is given of the main spectroscopic and structural properties of known tin(]3) compounds. Chapter 2 describes the general synthetic methods employed for the formation of tin(II)-oxygen heterocyclic compounds. A range of catecholate and related complexes of tin(II) were synthesized and the role of the substituent investigated with regard to their physical properties, especially their solubilities. The use of 4-nitrocatechol leads to a soluble product, {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}>sub>n</sub>, which enabled it to be studied spectroscopically and its solid state structure to be determined. The nature of the bonding in {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}_n was investigated using Extended Hiickel molecular orbital calculations. Chapter 3 describes the chemical reactivity of the novel, soluble, tin(II)-oxygen heterocycle {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}_n. Reaction with iodine gives SnI₂ [O-4-NO₂-C₆H₃O][OC₄H₈]<sub>2<sub>. Reaction with the Lewis base such as 1,2-diaminopropane gives Sn[NH₂CH₂CH(Me)H₂N][O-4-NO₂-C₆H₃O][OC₄H₈], whilst benzyltriethylammonium chloride gives {[Et₃BzN][SnCl(O-4-NO₂-C₆H₃O)]}_n. The solid-state structure of the compound consists of polymeric chains of [SnCl(O-4-NO₂-C₆H₃O)]^- and associated [Et₃BzN]⁺ cations. Reaction with BF₃.Et₂O gives the adduct F₃B.Sn[O-4-NO₂- C₆H₃O][OC₄H₈]. Reaction with W(CO)<sub>5_{thf gives {(OC)₃W.Sn[(O-4-NO₂- C₆H₃O)(OC₄H₈)]}₂ in which the tungsten atoms are believed to be bound η⁶ to the aromatic rings. Reaction with bis(triphenylphosphine)platinum-ethylene or tris(triphenylphosphine)platinum gives {PtH[PPh₃]₃}{[μ₂-O][μ₂-OH][Sn(O-4-NO₂- C₆H₃O)]₂}, the anion containing tin(II) and tin(IV) centres. Reaction with RhCl[CNC₈H₉]₃ gives {RhCl[CNC₈H₉]₃[μ₂-Sn(O-4-NO₂-C₆H₃O)]}₂. Reaction with Ph₃PAuCl gives the cluster Au₄(PPh₃)₄(μ₂-SnCl₃)₂, which is the first known example of a compound containing a μ₂-SnX₃ fragment. In comparison with SnCl₂, {Sn[O-4-NO₂- C₆H₃O][OC₄H₈]}_n only weakly inserts into the platinum-chlorine bonds of PtCl₂(dppe). Two molar equivalents of SnCl₂ reacts with PtCl₂(dppe) to give Pt(dppe)(SnCl₃)₂. Addition of a further equivalent of SnCl₂ in the presence of tetraethylammonium chloride gives [Et₄N][Pt(dppe)(SnCl₃)₃]. The platinum centre in this ion has a distorted trigonal bipyramidal geometry. Chapter 4 describes the synthesis of a number of tin(II)-sulphur heterocycles. The reaction between Sn[SC₆H₄S] and TMEDA gives a soluble adduct, Sn[SC₆H₄S]TMEDA. A number of tin(II)-nitogen heterocycles were also synthesized. Their intense colours and their instability towards air oxidation indicated that they were monomeric in the solid-state. Chapter 5 outlines the basis for non-linear optical properties, especially their SHG effects. A wide range of tris(catecholato)tin(IV) compounds were synthesized and tested for SHG activity. A number were found to have a significant SHG effect, especially [(O-4- NO,sub>2}-C₆H₃O)₃Sn][NHEt₃]₂, which has an SHG effect 1.33 x urea.

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The aim of this study was to investigate the removal of cobalt from zinc sulfate solution by cementation with the help of conventional and new type of additives that were 4% Sn-zinc alloy powder and 10% Sn-zinc alloy powder, respectively. Synthetic leach solutions containing 150 g/l Zn and 75 mg/l Co were prepared and used in all of the experiments. The parameters researched with the conventional method were the amount of arsenic trioxide and the effect of copper sulfate on cementation of cobalt. While using the alloys, the parameters studied were the amounts of arsenic trioxide, copper sulfate and tin containing zinc alloy powder additions, cementation duration and temperature. The difference in the optimization of alloy additions was in the amount of addition of arsenic trioxide. The amount of 4%Sn-zinc alloy powder was tried to be optimized with the addition of arsenic trioxide whereas the optimization was tried to be done without any arsenic addition while using 10%Sn-zinc alloy. The XRD and SEM studies of the cementates were also performed. The obtained results indicated that tin containing alloys were much better than pure zinc. With the additions of 4 g/l 4%Sn-Zn alloy dust, 1.2 g/l CuSO4.5H2O, 0.12 g/l As2O3 and in 2 hours of cementation duration at 85-90oC, the maximum amount of cobalt cementation efficiency was achieved. The experiments indicated that cobalt in the solution could be reduced to about 2 mg/l by using 10%Sn-zinc alloy powder with an initial Sn/Co weight ratio of 13.25:1 without the addition of arsenic trioxide at 85oC in 2 hours of cementation duration.

The interactions between ligands and transition metals have been an essential subject in inorganic chemistry. Other than the commonly known L-type (two-electron donors) and X-type ligands (one-electron donors), Z-type ligands (two-electron acceptors) have begun to surface in the past decade. Capable of drawing a pair of d-electrons away from a metal, Z-ligands affect the electronic structures of transition metals leading to fascinating properties as well as reactivity. In particular, recent advance in Z-ligand chemistry have resulted in the discovery of transition metal borane complexes featuring metal → boron interactions. Owing to the presence of a metal → boron interaction which stabilizes the low valent state, these complexes have been shown to activate small molecules such as H2, CO2, and CHCl3. Further, the concept of Z-ligand has been extended to s- and d-block Lewis acids. In spite of these achievements, Z-ligands that contain Group 14-16 elements as Lewis acids remain scarce and relatively unexplored. For this reason, we have launched a series of investigations targeting complexes with transition metal → Group 14-16 interactions. These investigations have allowed us to synthesize a series of novel complexes with palladium, platinum, or gold as metallobasic late transition metals and tin, antimony, bismuth, and tellurium as Lewis acids. The transition metal → Lewis acid interactions of these complexes, which are supported by o-phosphinophenylene, 1,8-naphthalenediyl or 8-quinolinyl buttresses, have been established experimentally and theoretically. Further, the reactivity of these complexes toward anions and oxidants has also been explored. These experiments have led to the discovery of tellurium-platinum complexes that sustain reversible two-electron redox processes including the photo-reductive elimination of chlorine. Other noteworthy outcomes of this research include the isolation of the first telluroxanyl-metal complex as well as the discovery of complexes with HgII → SbV interactions.

Thesis (M.S.)--State University of New York at Binghamton, Program of Materials Science and Engineering, 2007. / Includes bibliographical references.