5 years ago

Conformational Change on a Bithiophene-Based Copolymer Induced by Additive Treatment: Application in Organic Photovoltaics

Conformational Change on a Bithiophene-Based Copolymer Induced by Additive Treatment: Application in Organic Photovoltaics
C. K. Oliveira, N. A. D. Yamamoto, L. Benatto, M. G. E. da Luz, H. C. Avila, M. Cremona, O. D. Lourenco, M. Koehler, L. S. Roman, C. F. N. Marchiori
In recent years the use of solvent additives for fabrication of polymer-based solar cells has become an important procedure to induce morphological changes at the system nanoscale, a critical step to improve device performance. Yet the actual effects of those additives on the polymer’s backbone conformations (with coupled variations on the electronic structure) remain very elusive. By combining different experimental and theoretical techniques, we show that the use of the solvent additive 1,8-diiodooctane (DIO) might influence the conformation of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2) chains resulting in improved properties of the film. We correlate this conformational variation with the photovoltaic response of F8T2:fullerene(C60) devices prepared using different DIO concentrations. We find that the efficiency of the devices increases more than 100%, and the hole mobility in the F8T2 films increases almost 1 order of magnitude with the use of DIO. A comparison between experimental data and the properties of the calculated structures suggests that the additive induces a higher density of syn conformers in the bithiophene unit of the copolymer backbone, planarizing the polymer’s geometry. The simulations indicate that this transition is very likely mediated by the electrostatic interaction between the iodine atom of the DIO and the heteroatoms of the bithiophene moiety. The higher degree of electronic delocalization and the enhancement of the interchain interactions improve the transport and the photovoltaic features of F8T2 layers. The use of solvent additive treatments to control conformational variations of the backbone might be a promising strategy to improve the optoelectronic properties of polymer-based devices.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b05427

DOI: 10.1021/acs.jpcc.7b05427

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.