Temperature-Dependent Hole Mobility and Its Limit in Crystal-Phase P3HT Calculated from First Principles

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Poly(3-hexylthiophene) (P3HT) is a key organic semiconductor.
• Understanding charge transport in P3HT is crucial for organic electronics.
• Disorder significantly affects charge transport in real P3HT samples.

Purpose of the Study:

• To determine the maximum hole mobility in ideal P3HT crystals.
• To elucidate the impact of electron-phonon coupling on charge transport.
• To provide a benchmark for understanding disorder effects in P3HT.

Main Methods:

• Ab initio calculations using density functional theory (DFT).
• Calculation of molecular transfer integrals, phonon frequencies, and electron-phonon coupling constants.
• Temperature-dependent transport property estimation without fitting parameters.

Main Results:

• Strong coupling between charge carriers and molecular vibrations was observed.
• Significant polaron effects and scattering were identified as key factors.
• An intrinsic mobility limit for ordered P3HT crystals was estimated.

Conclusions:

• The study provides a theoretical mobility limit for P3HT, essential for evaluating real-world devices.
• Microscopic insights into polaron formation and phonon-mediated transport were gained.
• Identified mechanisms offer guidance for optimizing P3HT-based organic electronic materials.