Polymorphism of organic semiconducting materials exerts critical effects on their physical properties such as optical absorption, emission and electrical conductivity, and provides an excellent platform for investigating structure–property relations. It is, however, challenging to efficiently tune the polymorphism of conjugated polymers in aggregated, semi-crystalline phases due to their conformational freedom and anisotropic nature. Here, two distinctly different semi-crystalline polymorphs (β1 and β2) of a low-bandgap diketopyrrolopyrrole polymer are formed through controlling the solvent quality, as evidenced by spectroscopic, structural, thermal and charge transport studies. Compared to β1, the β2 polymorph exhibits a lower optical band gap, an enhanced photoluminescence, a reduced π-stacking distance, a higher hole mobility in field-effect transistors and improved photocurrent generation in polymer solar cells. The β1 and β2 polymorphs provide insights into the control of polymer self-organization for plastic electronics and hold potential for developing programmable ink formulations for next-generation electronic devices.
Bibliographical noteFunding Information:
This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 747422, from the Netherlands Organisation for Scientific Research (016. Veni.192.106), from the Chinese Academy of Sciences (Grant No. XDB12020200), and from King Abdullah University of Science and Technology (KAUST). The research also received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) (Grant Agreement no. 607585, project OSNIRO), the European Research Council (ERC Grant Agreement No. 33903), and the Ministry of Education, Culture, and Science (Gravity program 024.001.035). T.M. acknowledges the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund (First TEAM/2017–3/26). The authors acknowledge Beamline 9 of the DELTA electron storage ring in Dortmund for GIWAXS measurements. The authors thank Mateusz Brzezinski for the discussion about GIWAXS analysis, and Christ Weijtens for UPS measurements.
© 2019, The Author(s).
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)