Altering the Microstructure of Conjugated Polymers in Solution via Microwave Irradiation

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Solution-processed conjugated polymers are key for organic electronics.
• Controlling polymer aggregation in solution is crucial for film microstructure and device performance.
• Current methods for controlling aggregation are challenging for mass production.

Purpose of the Study:

• To investigate the effect of microwave (MW) heating on the solution-state aggregation of conjugated polymers.
• To understand how MW heating influences thin film microstructure and charge transport properties.
• To demonstrate a scalable and efficient method for enhancing polymer-based electronic devices.

Main Methods:

• Microwave (MW) heating applied to poly-[N,N'-bis-(2-octyldodecyl)-naphthalene-1,4,5,8-bis-(dicarboximide)-2,6-diyl]-alt-5,5'(2,2'bithiophene) (P(NDI2OD-T2)) in chlorobenzene.
• In situ optical spectroscopies (absorption and photoluminescence) to monitor polymer chain ordering.
• In situ small-angle X-ray scattering (SAXS) to analyze solution structural changes and aggregate formation.

Main Results:

• MW heating induced controllable swelling-collapsing dynamics in the polymer solution, leading to ordered aggregates.
• Thin films processed with MW heating showed significantly improved microstructure.
• Transistor devices fabricated from MW-treated solutions achieved high saturation field-effect mobility values up to 0.45 cm² V⁻¹ s⁻¹.

Conclusions:

• MW heating is a versatile and energy-efficient technique for controlling conjugated polymer aggregation and enhancing thin film microstructure.
• This method offers rapid operation and scalable fabrication for high-performance organic electronic devices.
• The findings provide insights into MW-induced aggregation mechanisms, applicable to various conjugated polymer systems.