118 CMDITR Review <strong>of</strong> Undergraduate Research Vol. 2 No. 1 Summer <strong>2005</strong>
Determination <strong>of</strong> Molecular Orientation <strong>of</strong> Self-OrganizedAggregates <strong>of</strong> New Liquid-Crystal Perylene DyeNatalie ThompsonGeorgia Institute <strong>of</strong> TechnologyNeal R. Armstrong, P. Alex Veneman,Armstrong Lab, Department <strong>of</strong> ChemistryThe <strong>University</strong> <strong>of</strong> ArizonaINTRODUCTIONOrganic compounds with π-conjugated systems which <strong>of</strong>tenexhibit high charge mobilities have a growing interest within thescientific community because <strong>of</strong> the possibility <strong>of</strong> creating organicfilms that can act as conducting materials. These compoundsare expected to be used to create cheaper electronics through allplasticcircuits (1) . Also, these materials could be used in otherorganic electronic applications, such as organic light emittingdiodes, organic photovoltaics, and organic field effect transistors.Liquid-crystalline organic materials are <strong>of</strong> interest due totheir ability to self-aggregate into columns. It is thought thatthe charge mobilities <strong>of</strong> the aggregates are related to the c<strong>of</strong>acialoverlap <strong>of</strong> the conjugated system. Brédas, et al. reported that thelargest splitting between the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital (LUMO)correlates with the c<strong>of</strong>acial overlap and then influences the hole(electron) transport <strong>of</strong> the aggregate. (1) Donley, et al. reportedthat c<strong>of</strong>acial overlap results in low activation energies for chargemigration. However, this migration, or hopping, prefers to movealong a certain axis <strong>of</strong> the aggregate. (2) Flora, et al. reporteda much higher charge mobility along the axis that is parallel tothe columnar axis, as opposed to perpendicular to it. (3) It hasbeen reported that discotic mesophase materials, such as phthalocyanines,triphenylenes, and hexabenzocoronenes, organize intocolumnar aggregates within films which are then stiff enough totransfer via horizontal transfer on a Langmuir-Blodgett trough.(4)Often these π-conjugated cores have surrounding side chainswhich are used to help control the self-organization process. Itis also thought that the side chains may help prevent electricalcross-talk between columnar aggregates due to their insulatingnature. (5)OBJECTIVES / THESISThis summer’s research focused on the characterization <strong>of</strong> arelatively new perylene-dianhydride-bisimide. Scheme 1The Derivatives <strong>of</strong> perylene-dianhydride-bisimide are <strong>of</strong> interestbecause <strong>of</strong> their high electron mobility, which would aidin the efficient transport <strong>of</strong> electrons in a thin film comprised <strong>of</strong>this molecule. Also, these derivatives have an electron affinitythat is high enough that the reaction with oxygen in the electrontransport is not significant, as compared with hole transportmaterials, indicating an ability to use organic electronics in air.The perylene-dianhydride-bisimide was made into thin films usingLangmuir-Blodgett methods and was then characterized byatomic force microscopy (AFM), UV-Vis transmission, FourierTranform Infrared (FTIR), reflective-absorptive infrared spectroscopy(RAIRS), and X-ray reflectivity (XRR).Scheme 1EXPERIMENTALLangmuir-Blodgett film preparationThe substrates for Langmuir-Blodgett thin films were siliconwafers, highly ordered pyrolytic graphite (HOPG), glass, andcommercial gold. The silicon wafers and glass slides were modifiedvia sonication for thirty minutes in a solution <strong>of</strong> 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and 1,3-diphenyl-1,1,3,3-tetramethyldisilazane(DPTMDS) in chlor<strong>of</strong>orm (5 : 5 : 90 :: HMDS: DPTMDS : CHCl 3). After sonication, the substrates remainedin solution until LB deposition. The preparation <strong>of</strong> the HOPGinvolved cleaving the substrate to obtain a flat clean surface. Thegold surface was rendered hydrophobic by sitting in a solution <strong>of</strong>benzyloxyethanethiol in ethanol overnight.Monolayer and multilayer films <strong>of</strong> N,N’-1,2,3-tridodecoxyphenyl-3,4,9,10-perylenetetracarboxylicdiimide(PTCDI) wereprepared on a Nima model 611D LB trough using chlor<strong>of</strong>orm asCMDITR Review <strong>of</strong> Undergraduate Research Vol. 2 No. 1 Summer <strong>2005</strong> 119
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TABLE OF CONTENTSSynthesis of Dendr
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SYNTHESIS OF DENDRIMER BUILDING BLO
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Synthesis of Nonlinear Optical-Acti
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quality of the XRD structures wasca
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Behavioral Properties of Colloidal
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Transmission electron microscopy ha
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Fabry-Perot modulators with electro
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QUANTIZED HAMILTON DYNAMICS APPLIED
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INVESTIGATING NEW CLADDING AND CORE
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Dr. Robert NorwoodChris DeRoseAmir
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SYNTHESIS OF TPD-BASED COMPOUNDS FO
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SYNTHESIS OF TPD-BASED COMPOUNDS FO
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SYNTHESIS AND ANALYSIS OF THIOL-STA
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