Thienoacenes represent an intriguing class of organic semiconducting molecules with potential applications in organic electronics. Some of thienoacenes have been reported with high charge carrier mobility in organic field-effect transistors (OFET). OFETs based on naphtho[2,1-b:3,4-b’]dithiophene (NDT) exhibited moderate device performance and low-band gap donor-acceptor copolymers based on NDT showed a promising solar power conversion efficiency. In this thesis, four novel series of thienoacenes based on naphtho[2,1-b:3,4-b’]dithiophene backbone were designed and synthesized for OFET applications. Firstly, a novel series of p-type semiconducting naphthodithieno[3,2-b]thiophene derivatives (NDTT-n) composed of six-fused aromatic rings were designed and synthesized (Figure 1). The OFETs based on NDTT-10, and NDTT-12 fabricated by vacuum deposition showed a hole mobility of 0.22 and 0.13 cm2/(Vs), respectively with Ion/Ioff above 107 after annealing at 80 oC. Secondly, the derivatives of NDT fused with benzene rings at the flanks of thiophene, namely NBBT-n (Figure 2) were also designed and synthesized. OFETs based on NBBTF-10 fabricated by vacuum deposition exhibited a hole mobility of 0.35 cm2/(Vs) with a current on/off ratio of 106 107 after annealing at 160 oC. Further extension of π-conjugation of NDTT by incorporating with fused thiophenes leading to a new NBTBT-n series was also developed (Figure 3). The OFETs fabricated by NBTBT-10 showed the hole mobility up to 0.25 cm2/(Vs) with a current on/off ratio of 105 106 after annealing at 220 oC. Lastly, two dimensionally π-extended, butterfly-shaped thienoacenes (Figure 4) were also synthesized. The OFETs based on SMB-10 fabricated by spin-coating showed the best performance in this series with an average mobility of 0.027 cm2/(Vs) for five devices and the highest mobility of 0.038 cm2/(Vs) with a current on/off ratio of 106 107 by from chloroform. Key words: organic semiconducting molecules, organic field-effect transistor, thienoacene, charge carrier mobility.
| Identifer | oai:union.ndltd.org:hkbu.edu.hk/oai:repository.hkbu.edu.hk:etd_oa-1195 |
| Date | 25 February 2015 |
| Creators | Li, Zhaoguang |
| Publisher | HKBU Institutional Repository |
| Source Sets | Hong Kong Baptist University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Open Access Theses and Dissertations |
| Rights | The author retains all rights to this work. The author has signed an agreement granting HKBU a non-exclusive license to archive and distribute their thesis. |
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