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URN etd-0815106-110610 Statistics This thesis had been viewed 2754 times. Download 1621 times. Author Pei-Chun Shun Author's Email Address No Public. Department Chemical Engineering Year 2005 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 84 Title STUDY ON THE SYNTHESIS AND CHARACTERIZATION OF REGIOREGULAR POLY(3-ALKYLTHIOPHENES) AND COPOLYMERS AND APPLICATION ON ORGANIC FIELD-EFFECT TRANSISTOR Keyword semiconductor poly(3-alkylthiophene) poly(3-alkylthiophene) semiconductor Abstract The regioregular of poly(3-alkylthiophene) (HT-P3ATs) (P3MT, P3HT, P3OT, P3DT, and P3DDT) with different length of the alkyl side chains can be synthesized successfully by GRIM (Grignard metathesis) method. Besides, we were also successfully synthesized copoly(3-alkyl-
thiophenes) (P3MTHT, P3MTOT, P3HTDT, and P3HTDDT). These polymers containing high percentage of head-to-tail coupling, can be easy of access a low energy, low space obstacle coplanar conformation, leading to highly conjugated polymer. HT-P3ATs and their copolymers possess better conductivity and optical properties, and can undergo self-assembly. And these materials have a significant practical impact in optoelectronic application-organic field-effect transistor (OFET).
The physical properties of these polymers were done by NMR, FTIR, EA, GPC, XRD, DSC, TGA, TMA, UV, PL, and CV. The regioregularity of these samples were calculated to be 80% ~ 97% using by NMR data. It is found that the molecular weights of P3ATs and copolymers were about 3,900-17,200 g/mol and 8,140-34,001 g/mol, respectively. These polymers exhibit a narrow PDI. The thermotropic transition behavior of these materials were examined by DSC, an increased in the length of the side chain decreased remarkably the melting point and exhibit an excellent thermal stability under 400 ℃. The XRD results indicate that poly(3-alkylthiophenes) and copolymers have a great order and crystalline structure. The UV-visible spectra of poly(3-alkylthiophenes) and copolymers show that red shift of λmax increase with increasing the level of regioregularity and that the copolymers has a higher conjugation. The bandgap calculated of poly(3-alkylthiophenes) and copolymers from UV-visible and exhibit a small bandgap. Besides, the poly(3-alkylthiophenes) and copolymers of PL emit yellow-orange light in CHCl3 solution state. The cyclic voltammetry can be calculated the values of oxidation potential, HOMO, and LUMO.
The characteristics of thin-film transistor (TFT) fabricated with P3ATs and copolymers have been investigated. The charge transport mobility, on/off current ratio, threshold voltage and subthreshold slope of P3AT OTFTs are 2.08 x 10 – 2 cm 2/Vs, 1 x 10 4, 10.5 V, 2.89 V/decade (P3HT) and 3.18 x 10 – 3 cm 2/Vs, 4.4 x 10 3, 10.5 V, 1.43 V/decade (P3OT), respectively. The charge transport mobility, on/off current ratio, threshold voltage and subthreshold slope of copolymer OTFT are 1.79 x 10 – 2
cm 2/Vs, 1 x 10 4, 11.6 V, 2.88 V/decade (P3MTOT) and 1.32 x 10 – 3 cm 2/Vs, 6.4 x 10 4, 12.1 V, 1.79 V/decade (P3MTHT), respectively.
Advisor Committee Chin-Tsou Kuo - advisor
Feng-Yu Tsai - co-chair
Shune-Long Wu - co-chair
Files Date of Defense 2006-07-31 Date of Submission 2006-08-16