Tuning Solution Aggregates and Thin Film Polymorphs in Conjugated Polymers via External Electric Field for...

Area of Science:

• Materials Science
• Organic Electronics
• Crystallography

Background:

• Tailoring polymorphic crystals of π-conjugated semiconducting polymers is essential for understanding structure-optoelectronic property relationships.
• Developing facile and generic strategies for polymorph control in these materials remains a significant challenge.

Purpose of the Study:

• To introduce an effective external electric field (EEF) strategy for adjusting the polymorphs of poly(3-butylthiophene) (P3BT) in thin films.
• To correlate different polymorphs with chain conformation and solution aggregation behavior.
• To investigate the impact of EEF-induced polymorph transformation on carrier transport properties.

Main Methods:

• Application of an external electric field (EEF) to poly(3-butylthiophene) (P3BT) thin films.
• Analysis of polymer chain conformation and aggregation in solution.
• Characterization of carrier transport properties in relation to polymorphs.

Main Results:

• P3BT without EEF exhibits a twisted chain conformation and weak aggregation, resulting in polymorph II.
• EEF application induces a planarized chain conformation and stronger aggregation, leading to a polymorph II-to-I transition.
• Carrier transport properties are strongly correlated with the observed polymorphs.

Conclusions:

• EEF is a robust method for tailoring polymorphs of conjugated polymers and their charge transport properties.
• This approach contributes to a deeper understanding of crystalline behaviors in polymers for optoelectronic applications.
• The EEF-induced polymorph transformation strategy is applicable to other conjugated polymers.