Step towards High Power Factor in Acidic-Doped Poly(3-hexylthiophene) Systems

Area of Science:

• Materials Science
• Organic Electronics
• Thermoelectrics

Background:

• Poly-(3-hexylthiophene) (P3HT) is a key organic semiconductor.
• Doping is crucial for enhancing P3HT's thermoelectric properties.
• F4TCNQ is a common but expensive dopant.

Purpose of the Study:

• To evaluate dodecylbenzenesulfonic acid (DBSA) as a dopant for P3HT.
• To investigate DBSA's effect on P3HT's morphology and electronic properties.
• To explore DBSA as a cost-effective and less toxic alternative dopant.

Main Methods:

• Spin-coating of P3HT thin films.
• Doping P3HT with varying concentrations of DBSA (0.0001% to 20% v/v).
• Characterization of electrical conductivity, Seebeck coefficient, and power factor.
• Atomic force microscopy (AFM) for surface morphology analysis.

Main Results:

• The optimal P3HT:DBSA composition (11% v/v DBSA) achieved a conductivity of 5.58 S·cm⁻¹, Seebeck coefficient of 69.7 μV·K⁻¹, and power factor of 2.706 μW·m⁻¹·K⁻².
• Seebeck coefficients ranged from 59 μV·K⁻¹ to 352.9 μV·K⁻¹ depending on DBSA concentration.
• Increased DBSA concentration reduced surface roughness, impacting conductivity.
• Thermoelectric performance is comparable to P3HT doped with sulfuric acid or F4TCNQ.

Conclusions:

• DBSA is a viable, cost-effective, and less toxic p-type dopant for P3HT.
• DBSA acts as both a dopant and surfactant, influencing film morphology.
• DBSA-doped P3HT shows promise for organic thermoelectric applications.