N-Type Organic Thermoelectrics: Improved Power Factor by Tailoring Host-Dopant Miscibility

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Fullerene derivatives are key in organic electronics.
• Improving miscibility between host and dopant molecules is crucial for high performance.
• Solution-processed organic thermoelectrics require enhanced electrical conductivity.

Purpose of the Study:

• To tailor the polarity of fullerene derivatives to enhance host-dopant miscibility.
• To improve the doping efficiency and electrical conductivity of organic thermoelectrics.
• To investigate the microstructural origins of enhanced properties.

Main Methods:

• Utilizing a hydrophilic fullerene derivative (PTEG-1) as the host and n-DMBI as the dopant.
• Conducting in-depth microstructural studies of the solution-processed thin films.
• Optimizing doping concentration and evaluating electrical conductivity and power factor.

Main Results:

• Achieved a doping efficiency of around 18%, a significant improvement over nonpolar samples (<1%).
• Obtained an optimized electrical conductivity of 2.05 S cm-1, the best for solution-processed fullerene derivatives.
• Observed a unique layered microstructure with n-DMBI dopants incorporated into the side chain plane, enhancing nanoscale miscibility.
• Attained a power factor of 16.7 µW m-1 K-2 at 40% dopant concentration.

Conclusions:

• Tailoring fullerene derivative polarity is an effective strategy to enhance host-dopant miscibility.
• The novel layered microstructure significantly contributes to high electrical conductivity in solution-processed organic thermoelectrics.
• This work presents a new approach for advancing n-type organic thermoelectric materials.