Lamellar-Paracrystallinity-Controlled Thermal Transport in Polymer Semiconductors.

Area of Science:

• Materials Science
• Polymer Physics
• Organic Electronics

Background:

• Thermal transport in polymer semiconductors is vital for organic electronic device performance, safety, and stability.
• The relationship between polymer structure and thermal transport properties is not well understood.
• Existing research has not fully explored the underlying physics of heat dissipation in these materials.

Purpose of the Study:

• To investigate the structure-property relationship governing thermal conductivity in polymer semiconductors.
• To identify the key factors controlling in-plane thermal transport in these materials.
• To provide insights for manipulating thermal conductivity in organic electronic devices.

Main Methods:

• Measured thermal conductivities of 11 polymer semiconductors using an improved suspended‑3ω technique.
• Analyzed the correlation between thermal conductivity and paracrystalline disorder of lamellar packing.
• Employed molecular dynamics simulations to understand vibrational coupling and interchain transport pathways.

Main Results:

• A strong correlation was found between thermal conductivity and lamellar packing paracrystallinity.
• In-plane thermal conductivity is predominantly controlled by lamellar paracrystallinity, surpassing backbone chemistry or π-π stacking effects.
• Tuning lamellar paracrystallinity altered thermal conductivity by up to approximately 40% within the same polymer.

Conclusions:

• Lamellar packing serves as the primary interchain thermal transport pathway, exhibiting more efficient vibrational coupling than π-π stacking.
• This study reveals distinct interchain pathways for charge and thermal transport in polymer semiconductors.
• Findings offer guidelines for optimizing thermal conductivity independently of electrical performance in advanced organic materials.