Synthesis of diketopyrrolopyrrole based conjugated polymers containing thieno[3,2-b]thiophene flanking groups for high performance thin film transistors

• Published in: Polymer chemistry 2017-06, Vol.8 (22), p.3431-3437
• Main Authors: Peng, Shih-Hao, Tu, Wei-Yi, Gollavelli, Ganesh, Hsu, Chain-Shu
• Format: Article
• Language: English
• Subjects: Charge transport; Conjugates; Field effect transistors; Optical properties; Polymers; Semiconductor devices; Synthesis (chemistry); Thin film transistors
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C7PY00402H

New donor–acceptor (D–A) conjugate polymers 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-(2 H ,5 H )-dione ( Br-TTDPP ) combined with three different electron-donating monomers bithiophene ( BT ), di(2-thienyl)ethene ( TVT ), and di(selenophene-2-yl)ethene ( SVS ) were synthesized. The optical band gap, electrochemical properties and organic field-effect transistor (OFET) device performance of the TTDPP -based polymers were systematically investigated. X-ray diffraction (XRD) was used to evaluate the molecular packing of the TTDPP-based polymers. Among three polymers, TTDPP-SVS showed the smallest d -spacing and the largest distance of 0.372 for π–π stacking. In particular, an OTFT having a TTDPP-SVS active layer showed the highest hole mobility of 0.196 cm 2 V −1 s −1 , the lowest threshold voltage down to −3.6 V, and the highest I on / I off ratio of 6.5 × 10 4 . This indicates that π-extended SVS significantly improves charge transport properties.