Synthesis, Optoelectronic, and Transistor Properties of BODIPY- and Cyclopenta[c]thiophene-Containing 蟺-Conjugated Copolymers

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• 作者：Sashi Debnath ; Saumya Singh ; Anjan Bedi ; Kothandam Krishnamoorthy ; Sanjio S. Zade
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 16, 2015
• 年：2015
• 卷：119
• 期：28
• 页码：15859-15867
• 全文大小：598K
• ISSN：1932-7455

文摘

Three new low-band-gap copolymers were synthesized by fusing dipyrromethene difluoroborane (BODIPY) as the acceptor (A) and thiophene-capped 5,5-bis(hexyloxymethyl)-5,6-dihydro-4H-cyclopenta[c]-thiophene (CPT) as the donor (D). The BODIPY unit was copolymerized through the 虁伪鈥?positions (1 and 7 positions) in P1 and through the 虁尾鈥?positions (2 and 6 positions) in P2 and P3. The additional acetylene unit between D and A in P3 enhanced the conjugation by minimizing the possible steric hindrance compared to that in P2, whereas P1 exhibited a more red-shifted absorption than P2 and P3 because of the more effective conjugaion through the 虁伪鈥?positions of BODIPY. Importantly, the optical band gaps (E_g^opt) obtained from the onset of the absorption spectra are 1.28, 1.71, and 1.57 eV for P1, P2, and P3, respectively. P1 has the lowest band gap for any CPT-containing polymer. In the best transistor devices, a mobility improvement by 4 orders of magnitude from 3.22 脳 10^鈥? cm² V^鈥? s^鈥? for P2 to 0.01 cm² V^鈥? s^鈥? for P1 was achieved. DFT calculations alongside measured charge-transport properties indicated that appreciable alterations in the optoelectronic properties of the polymers were achieved through minor changes in their structural features. The polymers were further characterized by thin-film X-ray diffraction, atomic force microscopy, and spectroelectrochemistry to investigate their material and electrochemical properties.