α,β-Unsubstituted meso -positioning thienyl BODIPY: a promising electron deficient building block for the development of near infrared (NIR) p-type donor–acceptor (D–A) conjugated polymers

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2018-01, Vol.6 (15), p.4030-4040
• Main Authors: Squeo, Benedetta M., Gregoriou, Vasilis G., Han, Yang, Palma-Cando, Alex, Allard, Sybille, Serpetzoglou, Efthymis, Konidakis, Ioannis, Stratakis, Emmanuel, Avgeropoulos, Apostolos, Anthopoulos, Thomas D., Heeney, Martin, Scherf, Ullrich, Chochos, Christos L.
• Format: Article
• Language: English
• Subjects: Butyric acid; Chemical synthesis; Crystal structure; Electron affinity; Electrons; Energy gap; Energy levels; Field effect transistors; Hole mobility; Optoelectronics; Polymers; Semiconductor devices; Thiophenes
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C7TC05900K

It is demonstrated that α,β-unsubstituted meso -positioning thienyl BODIPY is an electron deficient unit that leads to the development of ultra low optical band gap ( E optg < 1 eV) π-conjugated D–A quarterthiophene polymers. Furthermore, it is revealed that the optoelectronic, electrochemical and charge transporting properties of the resulting α,β-unsubstituted meso -positioning thienyl BODIPY quaterthiophene-based polymers are alkyl side chain positioning dependent. Tail-to-tail (TT) positioning of the alkyl side chains at the two central thiophenes of the quaterthiophene segment results in lower E optg, higher energy levels and increased hole mobility as compared to head-to-head (HH) positioning. Finally, even though the synthesized polymers exhibit high electron affinity, higher even than that of the fullerene derivative [6,6]-phenyl-C 71 -butyric acid methyl ester ( PC71BM ), they present only p-type behaviour in field effect transistors (FETs) independent of the alkyl side chain positioning.