Organic Electronic and Optoelectronic Devices Based on Diphenylamine End-group Polymers
Type of Degreedissertation
Chemistry and Biochemistry
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This work mainly focuses on making a series of organic diodes and photovoltaic devices based on electroconducting polymers with diphenylamine end-groups for their monomers. Most of them are with structural motif of R-X-R. Bilayer electrochemistry and spectroelectrochemistry results show the electron blocking and electron trapping in these bilayers. Solid-state electronic devices were fabricated with oxidatively electropolymerizing polymeric bilayers on gold covered or transparent electroconductive ITO (Indium Tin Oxide) glass slides, followed by Ga/In eutectic liquid droplet, soft contacts by gold leaf, or thermal evaporation of Ag to make an electrical contact. The final part of this work also investigated the surface metallization of high performance commercial fibers, as well as its effect on fiber mechanical properties. Modified electrodes with current rectification were assembled and investigated by electrochemical methods. The modification materials include poly(FD), a naturally monopolar material (p-type) and poly(DNTD), poly(DPTD), poly(Cl4DPTD), bipolar organic materials. All these materials are easily grown on each other from their monomer solutions. When one of these bipolar materials was grown on poly(FD) modified Au electrode, the out-layer will be electrochemically isolated from poly(FD) and bilayers show different current responses in positive and negative potentials. p-n junction semiconductors with these structures are also characterized and analysized by current-voltage responses and Shockley diode equation. Changing the assembly order of bilayer will switch the device bias direction. Spectroelectrochemistry experiments on these bilayers were performed in a home-made electrochemical cell coupled with a UV-Vis. spectrometer. The purpose is to understand the electron transfer behavior in different bilayers. The electron blocking was verified by applying different potentials to these bilayers with poly(FD) as inner, which poly(FD) is directly grown on ITO. Electron trapping behavior was charaterized in those bipolar materials with different reduction potentials. Four different electropolymerizable monomers with perylene diimide core and their solid state polymers were investigated by different spectral methods. P-n heterojunction organic photovoltaic cells were fabricated followed by the thermal evaporation of CuPc and Ag back electrode. Results show that the chlorination of perylene bay area could improve the ability of electron conduction and a device with this compound gave better performance than the others. Gold nanoparticles were incorperated between p-n junction to improve the photovoltaic performance since metallic nanoparticles transfer absorbed incident light to enhance plasmonic resonance at the interface of metal and organic dielectric materials.