Boosting Thermoelectric Performance of Semicrystalline Conducting Polymers by Simply Adding Nucleating Agent

Area of Science:

• Materials Science
• Polymer Science
• Thermoelectrics

Background:

• Optimizing thermoelectric performance in semiconducting polymers requires precise microstructure control.
• Current methods for microstructure control, such as alignment, are often complex and challenging.
• Nucleating agents, common in traditional polymer industries, offer a potential simpler approach.

Purpose of the Study:

• To investigate a straightforward strategy for enhancing thermoelectric properties of semi-crystalline polymer films.
• To explore the use of minimal amounts of nucleating agents to modulate polymer crystallization.
• To optimize the loading of N,N'-(1,4-phenyl)diisonicotinamide (PDA) as a nucleating agent in PBTTT-C14.

Main Methods:

• Blending varying low concentrations (less than 1 wt%) of N,N'-(1,4-phenyl)diisonicotinamide (PDA) into poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14).
• Systematic investigation of crystallization behavior and structural disorder.
• Measurement of electrical conductivity and power factor, followed by ion exchange doping.

Main Results:

• An optimal PDA loading of 0.9 wt% increased the crystallization degree of PBTTT-C14 films by 45%.
• PDA-modified films achieved a maximum electrical conductivity of 1,894 S cm⁻¹ and a power factor of 176 µW m⁻¹ K⁻², representing significant improvements over pristine films.
• Enhanced charge transport efficiency was attributed to polymer chain extension and reduced grain boundary resistance.

Conclusions:

• Minimal addition of nucleating agents like PDA is an effective strategy to control semiconducting polymer microstructure and enhance thermoelectric properties.
• The optimized PDA-modified PBTTT-C14 films demonstrate superior thermoelectric performance.
• This approach provides a pathway for developing advanced thermoelectric materials and polymer-based electronics.