Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 116-126).

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

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.

Made available in DSpace on 2014-06-11T19:35:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-19Bitstream added on 2014-06-13T21:08:03Z : No. of bitstreams: 1 ravaro_lp_dr_bauru.pdf: 1658046 bytes, checksum: 983c4581a9ddd20f1ea856686a19f802 (MD5) / Dióxido de estanho (snO2) é um semicondutor óxido do tipo-n, que é transparente na região do ultravioleta/visível. Possui muitas aplicações como, por exemplo, eletrodos transparente, sensores de gás, coletores e dispositivos optoeletrônicos. Quando dopado com íons terras-raras, SnO2 pode ser utilizado na confecção de dispositivos para comunicação óptica, principalmente na forma de filmes finos. A modificação do pH da suspensão coliodal, a partir do pH neutro, mostrou-se um artifício eficaz no controle das propriedades ópticas, elétricas e estruturais das amostras obtidas sem a necessidade da utilização de compostos orgânicos para a estabilização do sistema coloidal e controle do tamanho da partícula. O pH ácido favorece a formação de ligações cruzadas (Sn-O-Sn) entre as partículas, com geração de aglomerados maiores observados nas medidas de MEV/FEG e maior concentração de defeitos superficiais identificados pelos modos de vibração S1 e S2 do espectro Raman. O pH ácido também reduz a resistividade, a energia de ativação e a energia de captura dos filmes obtidos. O espectro de emissão para uma pastilha dopada com 2% de érbio, obtida com pH4, apresentou leve alteração das componentes dos níveis Stark referente aos íons Er3+ localizados na superfície desorganizada do grão. O processamento de filmes por litrografia positiva (lift-off) beneficiou a estabilidade elétrica e a reprodutividade de dados em medidas elétricas, facilitando a interferência dos resultados. Para medidas decaimento da condutividade foto-excitada com um LED de InGan (450 nm), foi possível observar valores positivo e negativo para a quantidade (Ecap-), indicando regiões distintas de temperatura com domínio da captura de elétrons por defeitos ou da mobilidade eletrônica / Tin dioxide (SnO2) is an n-type semiconductor, which is transparent in the ultraviolet/visible range. It has many applications, such as transparent electrodes, gas sensors, solar collectors and optoelectronic devices. When doped with rare-earth ions, SnO2 may be used for building optical communication devices, mainly in the form of thin films. Modification of pH of colloidad supension from neutral pH has shown an efficient tool on the control of optical, electrical and structural properties, which can be obtained without requirement of using organic compounds for stabilization of colloidal system and particle size control. Acid pH favors the formation of cross-linked bonds (Sn-O-Sn) between particles, with gernation of larger agglomerates, as observed in the SEM/FEG images and higher concentration of surface defects as identified by the vibration modes S1 and S2 of the Raman spectra. The acid pH also reduces the resitivity, the activation energy of the deeper energy level and the capture energy of obtained films. The emission spectra for a 2%Re3+- doped pellet, obtained with pH4, presents a slight variation of the Stark levels related to Er3+ ion located at the disorganized grain surface. Film processing by lift-off photolighography has led to electrical stability and data reproducibility in electrical measurements, helping the results interpretation. For measurements of decay of conductivity photo-induced by an InGaN LED (450nm), it was possible to observe positivo as well a negative values for the quantity (Ecap-), indicating distinct regions of temperature, either dominated by the electron capture by defects or by electronic mobility

Orientador: Luis Vicente de Andrade Scalvi / Banca: Fenelon Martinho Lima Pontes / Banca: Jose Humberto Dias da Silva / Banca: Andrea Simone Stucchi de Camargo Alvarez Bernardez / Banca: Virgilio de Carvalho dos Anjos / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat , tem carater institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: Dióxido de estanho (snO2) é um semicondutor óxido do tipo-n, que é transparente na região do ultravioleta/visível. Possui muitas aplicações como, por exemplo, eletrodos transparente, sensores de gás, coletores e dispositivos optoeletrônicos. Quando dopado com íons terras-raras, SnO2 pode ser utilizado na confecção de dispositivos para comunicação óptica, principalmente na forma de filmes finos. A modificação do pH da suspensão coliodal, a partir do pH neutro, mostrou-se um artifício eficaz no controle das propriedades ópticas, elétricas e estruturais das amostras obtidas sem a necessidade da utilização de compostos orgânicos para a estabilização do sistema coloidal e controle do tamanho da partícula. O pH ácido favorece a formação de ligações cruzadas (Sn-O-Sn) entre as partículas, com geração de aglomerados maiores observados nas medidas de MEV/FEG e maior concentração de defeitos superficiais identificados pelos modos de vibração S1 e S2 do espectro Raman. O pH ácido também reduz a resistividade, a energia de ativação e a energia de captura dos filmes obtidos. O espectro de emissão para uma pastilha dopada com 2% de érbio, obtida com pH4, apresentou leve alteração das componentes dos níveis Stark referente aos íons Er3+ localizados na superfície desorganizada do grão. O processamento de filmes por litrografia positiva (lift-off) beneficiou a estabilidade elétrica e a reprodutividade de dados em medidas elétricas, facilitando a interferência dos resultados. Para medidas decaimento da condutividade foto-excitada com um LED de InGan (450 nm), foi possível observar valores positivo e negativo para a quantidade (Ecap-), indicando regiões distintas de temperatura com domínio da captura de elétrons por defeitos ou da mobilidade eletrônica / Abstract: Tin dioxide (SnO2) is an n-type semiconductor, which is transparent in the ultraviolet/visible range. It has many applications, such as transparent electrodes, gas sensors, solar collectors and optoelectronic devices. When doped with rare-earth ions, SnO2 may be used for building optical communication devices, mainly in the form of thin films. Modification of pH of colloidad supension from neutral pH has shown an efficient tool on the control of optical, electrical and structural properties, which can be obtained without requirement of using organic compounds for stabilization of colloidal system and particle size control. Acid pH favors the formation of cross-linked bonds (Sn-O-Sn) between particles, with gernation of larger agglomerates, as observed in the SEM/FEG images and higher concentration of surface defects as identified by the vibration modes S1 and S2 of the Raman spectra. The acid pH also reduces the resitivity, the activation energy of the deeper energy level and the capture energy of obtained films. The emission spectra for a 2%Re3+- doped pellet, obtained with pH4, presents a slight variation of the Stark levels related to Er3+ ion located at the disorganized grain surface. Film processing by lift-off photolighography has led to electrical stability and data reproducibility in electrical measurements, helping the results interpretation. For measurements of decay of conductivity photo-induced by an InGaN LED (450nm), it was possible to observe positivo as well a negative values for the quantity (Ecap-), indicating distinct regions of temperature, either dominated by the electron capture by defects or by electronic mobility / Doutor

Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The aim of this thesis is to use tin-mediated reactions to differentiate between the four zones in the myo-inositol ring that consists of five contiguous equatorial and one axial hydroxyl groups. It is expected to give chemical control over the hexitol that can be put to good use in commercializing the phosphate derivatives of myo-inositol that are of pharmaceutical value. As point of departure 1,2-0-cyclohexylidene-myo-inositol (II.I) was synthesized that contains a tetrol with one end adjacent to an axial acetal oxygen and the other end adjacent to an equatorial acetal oxygen. The selective protection of position 3 (Dmyo- inositol) was investigated. Various problems lead to the selective silylation of the acetal at position 5. The silane forms the basis of the subsequent investigation because the cyclitol is now divided into an isolated mono-ol and a trans-diol allowing for easier differentiation between the various hydroxyl groups. It was indeed possible to differentiate the trans-diol from the mono-ol by using carbonylation and allylidenation. Ring closure occurs in both cases. In the carbonylation case the resultant five-membered ring is less stable than that of the allylidene due to the Sp² hybridized carbon atom of the carbonate compared to theSp³ hybridized carbon of the allylidene group. Preliminary work was done on the racerrue 1,2-0-cyclohexylidene-myo-inositol (II.VII) in order to use the acquired technology on the chiral camphor analog. The transition from racemic to chiral proved problematic since the camphor acetal is difficult to prepare and its selective silylation differs from that observed for cyc1ohexylidene. The camphor acetal itself was silylated in the process. (S)-( -)-Camphanic chloride was therefore used as chiral auxiliary in the protection of position six of the racemic 1,2,3,4,5-protected myo-inositol, thus solving the problems encountered in the protection of position six whilst combining the protection and chiral induction steps. The resultant diastereomers could both be used in the synthesis of IP₃ and IP₄ respectively, eliminating the disposal of half ofthe product. This project lead to the development of useful chiral differentially protected myoinositol derivatives, which could be useful in synthesis of various other myo-inositol derivatives. Besides the synthesis of useful chiral differentially protected myo-inositol derivatives, this investigation developed new applications in the tin-mediated derivatization of sugars. The following compounds were synthesized during this investigation. Bold numbers indicates novel compounds. / AFRIKAANSE OPSOMMING: Die doel van hierdie proefskrif is om met behulp van tin-bemiddelde reaksies onderskeid te maak tussen die vier sones in die mia-inositolring, wat bestaan uit vyf aaneenlopende ekwatoriale hidroksigroepe en een aksiale hidroksigroep. Die verwagting was om vinnig, effektiewe chemiese beheer oor die genoemde heksitol te verkry om sodoende chemies en kommersiëel munt te slaan uit die farmaseutiese werking van die fosfaatafgeleides van mia-inositol. As eerste uitgangspunt is 1,2-0-sikloheksilideen-mia-inositol (II.I) berei, wat lei tot die vorming van 'n tetrol waarvan die een punt naasliggend aan 'n aksiale asetaalsuurstofatoom en die ander punt naasliggend aan 'n ekwatoriale asetaalsuurstof is. As voortsetting is die selektiewe beskerming van posisie 3 (D-mia-inositol) ondersoek. Velerlei probleme lei tot die selektiewe sililering van die asetaal by posisie 5 (II.VII). Die silieleter vorm die basis van al die daaropvolgende ondersoeke omdat dit die siklitol in 'n trans-diol en 'n geïsoleerde mono-ol verdeel en die verskillende hidroksigroepe daarvan makliker van mekaar onderskei kan word. Dit is inderdaad moontlik om die trans-diol van die mono-ol te onderskei deur karbonilering of allilidenering. In albei gevalle vind ringannulering plaas. In die geval van die karbonilering is die gevormde vyflidring minder stabiel as wat die geval is vir die allilideengroep. Die rede hiervoor is dat die karbonaatkoolstofatoom Sp²- gehibridiseer is terwyl die ooreenstemmende koolstofatoom van die allilideen Sp³- gehibridiseer is. Ontwikkelingswerk is op die rasemiese 1,2-0-sikloheksilideen-mia-inositol (II.VII) gedoen ten einde dit op die chirale kamferasetaalanaloog toe te pas. Die oorgang van rasemies na chiraal is egter problematies aangesien die kamferasetaal moeiliker vorm en selfs as dit vorm toon die reaksies, soos byvoorbeeld die sililering, ander selektiwiteit as wat die geval is vir die rasemiese mengsel. Sililering van die kamferasetaallei tot sililering van die kamfer self. (S)-(-)-kamfanoïelchloried is gevolglik as chirale hulpreagens gebruik om posisie 6 van die rasemiese 1,2,3,4,5-beskermde-mia-inositol te beskerm. Hierdie benadering los die problematiek rondom die beskerming van posisie 6 sowel as die induksie van chiraliteit op. Die twee diastereomere wat op hierdie wyse vorm, kan albei in die sintese van onderskeidelik IP₃ en IP₄ gebruik word, wat die verlies aan helfte van die produk verhoed. Behalwe die daarstelling van bruikbare chirale differensiëel-beskermde mioinositolafgeleides wat gebruik kan word om 'n verskeidenheid chirale mioinositolafgeleides te berei, het hierdie ondersoek nuwe toepassings in tin-bemiddelde derivatisering van suikers daargestel. Die volgende verbindings is gedurende die verloop van hierdie ondersoek gesintetiseer, waar verbindings vir die eerste keer gesintetiseer is word dit aangedui deur die verbinding se nommer vet (bold) te druk.

Thesis (M.S.)--State University of New York at Binghamton, Department of Physics, 2006. / Includes bibliographical references.

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