The optical, electrical and field effect properties of the porphyrin derivatives
| Autor: | Yung-Chou Chen, 陳永洲 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 In this research we investigate the transport and optical properties of three kinds of single crystals 5,10,15,20-tetrakis (4-N-ethylpyridyl) porphyrin salts (TEPyP-ions). The electrical conductivity exhibits high anisotropy, in that the conductivity along the stacking column, which is equal to 3.2 for sample TEPyP-4I, is three orders of magnitude larger than that perpendicular to the stacking column. In comparison to the solution spectra, the crystal spectra exhibit a blue shift of 0.09 eV in the B band and red shifts of 0.05 - 0.09 eV in the Q bands. The energy shifts are attributed to the exciton coupling interaction of the porphyrin molecules. Polarized reflectance measurements of the crystals reveal that the anisotropic reflectance is most intense when the light polarization is parallel to the molecular plane. The complex dielectric function and optical conductivity associated with each electronic transition are calculated based on analysis with a dielectric-function model. We also investigate the organic thin-film transistors fabricated employing the newly synthesized compound 5,10,15,20-(tetrakis(4-dodecoxylphenylethynyl)porphyrinato) zinc(II) (Zn-TDPP) as the active layer. The porphyrin was processed with side-chain substitution in the meso-position of the macrocycle. The organic film deposited by spin coating from a pyridine solution before being annealed in a furnace in argon gas to form homogenous polycrystals. Staggered source and drain gold contacts were made by argon ion sputtering with a stencil plate. The organic field-effect transistor (OFET) operates in the p-channel, accumulation-mode. The linear and saturation regimes were identified from the output and transfer characteristics. Carrier mobility, threshold voltage and ON/OFF ratio were calculated. The results show that the side-chain substitution greatly increased the solubility of the Zn-TDPP. The solution-processing technique can be used to fabricate porphyrin thin-film OFETs with a lower annealing temperature. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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