Date of Award

8-27-2019

Publication Type

Master Thesis

Degree Name

M.A.Sc.

Department

Chemistry and Biochemistry

Keywords

Polymer blending, Semiconductors, Stretchable electronics

Supervisor

Rondeau-Gagné, S.

Rights

info:eu-repo/semantics/openAccess

Abstract

A new strategy for influencing the solid-state morphology of conjugated polymers was developed through physical blending with a low molecular weight branched polyethylene (BPE). This non-toxic and low boiling point additive was blended with a high charge mobility diketopyrrolopyrrole (DPP)-based conjugated polymer and a detailed investigation of both electronic (Chapter III) and mechanical (Chapter IV) properties was performed. The new blended materials were characterized by various techniques, including X-ray diffraction, UV-Vis spectroscopy and atomic force microscopy (AFM). Interestingly, the branched additive was shown to reduce the crystallinity of the conjugated polymer, while promoting aggregation and phase separation in the solid-state. The performance of the new branched polyethylene/conjugated polymer blends was also investigated in organic field-effect transistors, which showed a stable charge mobility, independent of the blending ratio. Furthermore, by using the new BPE additive, the amount of conjugated polymer required for the fabrication of organic field-effect transistor devices was reduced down to 0.05 wt.%, without affecting charge transport, which is very promising in a large-scale fabrication of organic-field effect transistors (OFET) devices. Moreover, BPE additive acts as a plasticizer, thus drastically decreasing the crystallinity of conjugated polymers which is beneficial for the development of stretchable and flexible electronic devices. The incorporation of BPE amount to the conjugated polymer leads to an increase of the crack onset strain of polymer blends and decrease in the number of cracks, as well as their width. Our results demonstrate that the physical blending of conjugated polymer with non-toxic, low-molecular weight BPE is a promising strategy for the modification and fine-tuning of the solid-state morphology of conjugated polymers without sacrificing their charge transport properties, thus creating new opportunities for the large-scale processing of organic semiconductors

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