| Summary: | 碩士 === 國立交通大學 === 應用化學系碩博士班 === 105 === New D-A systemic copolymers based on 3,6-bis(2-bromothieno-[3,2-b]thiophen-5-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]-pyrrole-1,4-(2H,5H)-dione (TTDPP) combined with three different electron-donating strength monomer bithiophene (BT), di(2-thienyl)ethene (TVT), di(selenophen-2-yl)ethene (SVS) were synthesized. These three polymers’ optical band gap, electrochemical properties and organic thin-film transistors (OTFTs) device performance were systematically investigated. PBTTDPP-BT containing flexible moiety BT and long conjugated chain could modulate the polymer’s energy level and show the good packing on X-ray Diffraction (XRD). In order to get the better molecular packing, the strategy of using double bond as backbone moiety was used to create TVT as a donor unit. PBTTDPP-TVT copolymer showed better packing ability. It showed that OFET mobility of PBTTDPP-BT and PBTTDPP-TVT were 0.0882 cm2 V-1 s-1, 0.0945 cm2 V-1 s-1, respectively. Sequentially, we replaced the sulfur atom with the selenium atom in TVT unit. SVS was also copolymerized with TTDPP to form the polymer PBTTDPP-SVS. PBTTDPP-SVS had smallest d-spacing among three copolymers in lamellar direction. It implied that PBTTDPP-SVS had better intrachain transport charge transfer. Furthermore, PBTTDPP-SVS had suitable HOMO level to help carrier inject into Au electrode from polymer. As a result, PBTTDPP-SVS showed the highest hole mobility of 0.196 cm2V-1s-1 and the lowest threshold voltage -3.60 V in this study.
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