High Charge Carrier Mobility, Low Band Gap Donor鈥揂cceptor Benzothiadiazole-oligothiophene Based Polymeric Semiconductors

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• 作者：Boyi Fu ; Jose Baltazar ; Zhaokang Hu ; An-Ting Chien ; Satish Kumar ; Clifford L. Henderson ; David M. Collard ; Elsa Reichmanis
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：November 13, 2012
• 年：2012
• 卷：24
• 期：21
• 页码：4123-4133
• 全文大小：803K
• 年卷期：v.24,no.21(November 13, 2012)
• ISSN：1520-5002

文摘

A series of benzothiadiazole oligothiophene and oligo(thienylene vinylene) donor鈥揳cceptor (D鈥揂) copolymers were synthesized and characterized. These low optical band gap materials (1.5 eV) are capable of absorbing photons in the range of 400鈥?00 nm and exhibit good thermal stability. Their hole mobilities, determined using an organic field-effect transistor (OFET) architecture, vary over a range of 3 orders of magnitude and strongly correlate with the molecular ordering and morphology of the respective thin films. Spin-coated films of the poly(benzothiadiazole-sexithiophene) PBT6, which exhibits a highly crystalline lamellar 蟺鈥撓€ stacked edge-on orientation on the OFET substrate, possesses a hole mobility of ca. 0.2 cm²/V路s. Vinylene-containing analogs PBT6V2 and PBT6V2鈥?/b> are amorphous and exhibit very low mobilities. The molecular weight of PBT6 has a strong influence on the electronic properties: a sample with a lower molecular weight exhibits a mobility approximately 1 order of magnitude lower than the high molecular weight homologue, and the absorption maximum is appreciably blue-shifted. The hole mobility of PBT6 is further enhanced by a factor of ca. 3 through fabrication of the OFET by drop casting. OFETs fabricated by this process exhibit mobilities of up to 0.75 cm²/V路s and I_ON/OFF ratios in the range of 10⁶鈥?0⁷. These results demonstrate the potential of incorporating benzothiadiazole units into polythiophene derivatives to develop high-mobility semiconducting polymers.

Keywords:

conjugated polymers; hole mobility; organic field-effect transistors