Investigation of lithium salt-nonionic surfactant mesophases and their applications in solar cells as gel electrolyte

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buir.advisorDağ, Ömer
dc.contributor.authorBarım, Gözde
dc.date.accessioned2016-01-08T20:05:50Z
dc.date.available2016-01-08T20:05:50Z
dc.date.issued2013
dc.descriptionAnkara : The Department of Chemistry and the Graduate School of Engineering and Science of Bilkent University, 2013.en_US
dc.descriptionThesis (Master's) -- Bilkent University, 2013.en_US
dc.descriptionIncludes bibliographical references leaves 81-88.en_US
dc.description.abstractSome salts and some nonionic surfactants self-assemble together into lyotropic liquid crystalline (LLC) mesophases. The salt can be either in aqueous solution phase or in its molten phase in the self-assembly process. Concentrated aqueous solutions of lithium salts (LiCl, LiBr, or LiI) and pluronics (triblock copolymers, such as P65, P85, P103, or P123) or 10-lauryl ether (C12H25(CH2CH2O)10OH, denoted as C12EO10) type nonionic surfactant mesophases were investigated in this thesis work. The LLC mesophases are well ordered between 5.0 and 25.0 salt/pluronics and 2.0 and 10.0 salt/C12EO10 mole ratios, and remain stable for months under the ambient conditions. The water molecules remain as the hydrates under open atmosphere in the LLC mesophases of lithium salts-nonionic surfactants. The lithium salt-pluronic LLC mesophases are birefringent and have a hexagonal mesophase in a broad range of salt concentrations. The unit cell of the mesophases increases and a transition from the hexagonal to a cubic mesophases occurs upon increasing the salt content of the media. Moreover the LLC mesophases are ordered and stable up to 25.0 salt to pluronic mole ratio. At higher salt content, one can observe either a disordered phase or co-existence of salt crystals and mesophase. There is a big demand on the gel electrolytes for dye sensitized solar cells (DSSC) in order to overcome solvent problems caused by liquid electrolytes. The LLC mesophases of LiI, LiCl and LiBr salts with 10-lauryl ether (C12EO10) has been considered as gel-electrolyte for the DSSC. We demonstrate that the LiI/I2 couple can be incorporated into above LLC mesophases of various lithium salt-nonionic surfactant systems. Those LLC phases, with LiI/I2 couple have been characterized by means of diffraction, microscopy, spectroscopy and conductivity measurements. The LLC mesophases diffract at small angles and do not show any phase segregation upon incorporating the LiI/I2 redox couple. The LLC mesophases of these systems are 2D hexagonal, and they remain stable under ambient conditions for months. In the LLC media, the iodide ion and iodine molecule react to produce triodide ion in the media. The iodide/triodide (I- /I3 - ) redox couples containing gel electrolytes were formed and their solar performance was investigated by using a solar simulator and a cell consisting of a dye sensitized anode (FTO-dye modified TiO2), gel-electrolyte, and a cathode (FTO-Pt nanoparticles). The LLC mesophases of various lithium saltnonionic surfactant systems with the I- /I3 - redox couple were characterized using POM (Polarized Optical Microscope), XRD (X-ray Diffraction), FT-IR (Fourier Transform Infrared Spectroscopy) and Raman techniques. These new LLC mesophases can be used as gel electrolytes in solar cells after incorporation of redox couple into the media and display responses as good as commonly used liquid electrolytes.en_US
dc.description.provenanceMade available in DSpace on 2016-01-08T20:05:50Z (GMT). No. of bitstreams: 1 0006983.pdf: 3255543 bytes, checksum: 49831dcb69bedee63e2eaa321bb0b91a (MD5)en
dc.description.statementofresponsibilityBarım, Gözdeen_US
dc.format.extentxvi, 91 leaves, illustrations, graphs, tablesen_US
dc.identifier.itemidB139145
dc.identifier.urihttp://hdl.handle.net/11693/17053
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectLyotropic Liquid Crystalen_US
dc.subjectMesophasesen_US
dc.subjectMolten Salten_US
dc.subjectConcentrated Aqueous Solutionen_US
dc.subjectSelf-assemblyen_US
dc.subjectSolar Cellen_US
dc.subjectGel Electrolyteen_US
dc.subjectRedox Coupleen_US
dc.subject.lccQD923 .B37 2013en_US
dc.subject.lcshLiquid crystals.en_US
dc.subject.lcshPorous materials.en_US
dc.titleInvestigation of lithium salt-nonionic surfactant mesophases and their applications in solar cells as gel electrolyteen_US
dc.typeThesisen_US
thesis.degree.disciplineChemistry
thesis.degree.grantorBilkent University
thesis.degree.levelMaster's
thesis.degree.nameMS (Master of Science)

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