Phase behavior of π-conjugated polymer and non-fullerene acceptor (PTB7-Th:ITIC) solutions and blends

Jung Yong Kim; Pawel Jarka; Barbara Hajduk; Henryk Bednarski; Urszula Szeluga; Tomasz Tański

doi:10.1038/s41598-022-25476-9

Phase behavior of π-conjugated polymer and non-fullerene acceptor (PTB7-Th:ITIC) solutions and blends

Sci Rep. 2022 Dec 2;12(1):20849. doi: 10.1038/s41598-022-25476-9.

Authors

Jung Yong Kim^{1

2}, Pawel Jarka³, Barbara Hajduk⁴, Henryk Bednarski⁴, Urszula Szeluga⁴, Tomasz Tański³

Affiliations

¹ Department of Materials Science and Engineering, Adama Science and Technology University, P.O. Box 1888, Adama, Ethiopia. jungyong.kim@astu.edu.et.
² Center of Advanced Materials Science and Engineering, Adama Science and Technology University, P.O. Box 1888, Adama, Ethiopia. jungyong.kim@astu.edu.et.
³ Institute of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian University of Technology, 44-100, Gliwice, Poland.
⁴ Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Skłodowska 34 Street, 41-819, Zabrze, Poland.

Abstract

Phase diagrams of ternary π-bonded polymer (PTB7-Th) solutions were constructed as a function of molecular weight, temperature, and electron acceptor species (ITIC, PC₆₁BM and PC₇₁BM). For this purpose, the Flory-Huggins lattice theory was employed with a constant χ interaction parameter, describing a binodal, spinodal, tie line, and critical point. Then, the morphologies of the blends composed of highly disordered PTB7-Th and crystallizable ITIC were investigated by atomic force microscopy. Subsequently, the surface polarities of the PTB7-Th:ITIC thin films were examined by water contact-angle goniometer, exhibiting a transition at the composition of ~ 60 ± 10 wt.% ITIC. Furthermore, X-ray diffraction indicated the presence of ITIC's crystallites at ≥ 70 wt.% ITIC. Hence, the PTB7-Th:ITIC system was observed to undergo a phase transition at ~ 60-70 wt.% ITIC.