The Critical Role of Electron Donating Thiophene Groups On the Mechanical and Thermal Properties of Donor-Acceptor Semiconducting Polymers

Authors

Song Zhang, University of Southern MississippiFollow
Michael U. Ocheje, University of WindsorFollow
Lifeng Huang, University of Southern Mississippi
Luke Galuska, University of Southern Mississippi
Zhiqiang Cao, University of Southern MississippiFollow
Shaochuan Luo, Nanjing UniversityFollow
Yu-Hsuan Cheng, National Taiwan University of Science and Technology
Dakota Ehlenberg, University of Southern Mississippi
Renée B. Goodman, University of Windsor
Dongshan Zhou, Nanjing UniversityFollow
Yi Liu, Lawrence Berkeley National LaboratoryFollow
Yu-Cheng Chiu, National Taiwan University of Science and TechnologyFollow
Jason D. Azoulay, University of Southern MississippiFollow
Simon Rondeau-Gagné, University of WindsorFollow
Xiaodan Gu, University of Southern MississippiFollow

Document Type

Article

Publication Date

3-13-2019

Department

Polymers and High Performance Materials

Abstract

Organic semiconducting donor–acceptor polymers are promising candidates for stretchable electronics owing to their mechanical compliance. However, the effect of the electron‐donating thiophene group on the thermomechanical properties of conjugated polymers has not been carefully studied. Here, thin‐film mechanical properties are investigated for diketopyrrolopyrrole (DPP)‐based conjugated polymers with varying numbers of isolated thiophene moieties and sizes of fused thiophene rings in the polymer backbone. Interestingly, it is found that these thiophene units act as an antiplasticizer, where more isolated thiophene rings or bigger fused rings result in an increased glass transition temperature (T_g) of the polymer backbone, and consequently elastic modulus of the respective DPP polymers. Detailed morphological studies suggests that all samples show similar semicrystalline morphology. This antiplasticization effect also exists in para‐azaquinodimethane‐based conjugated polymers, indicating that this can be a general trend for various conjugated polymer systems. Using the knowledge gained above, a new DPP‐based polymer with increased alkyl side chain density through attaching alky chains to the thiophene unit is engineered. The new DPP polymer demonstrates a record low T_g, and 50% lower elastic modulus than a reference polymer without side‐chain decorated on the thiophene unit. This work provides a general design rule for making low‐T_g conjugated polymers for stretchable electronics.

Publication Title

Advanced Electronic Materials

Recommended Citation

Zhang, S., Ocheje, M. U., Huang, L., Galuska, L., Cao, Z., Luo, S., Cheng, Y., Ehlenberg, D., Goodman, R. B., Zhou, D., Liu, Y., Chiu, Y., Azoulay, J. D., Rondeau-Gagné, S., Gu, X. (2019). The Critical Role of Electron Donating Thiophene Groups On the Mechanical and Thermal Properties of Donor-Acceptor Semiconducting Polymers. Advanced Electronic Materials.
Available at: https://aquila.usm.edu/fac_pubs/16191