A solid state density functional study of crystalline thiophene-based oligomers and polymers

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Thiophene-based polymers are crucial in organic electronics.
• Accurate structural and energetic characterization is vital for material design.
• Previous studies reported crystal structures for P3MBT and P3BT using X-ray diffraction.

Purpose of the Study:

• To perform molecular modeling of thiophene-based oligomers and polymers using solid-state DFT.
• To validate a standard quantum mechanical approach against experimental data and custom force fields.
• To confirm the stability of reported crystal structures through energy minimization.

Main Methods:

• Solid-state density functional theory (DFT) calculations.
• Perdew and Wang (PWC) functional with a double-ζ polarized numerical basis set (DNP).
• Comparison with experimental crystal structures and in-house force field parameters.

Main Results:

• The PWC/DNP method provides a balanced description of structure and energetics for thiophene polymers.
• Computational results show good agreement with experimental data and force field methods.
• DFT minimizations confirm that the experimental crystal structures of P3MBT and P3BT represent energy minima.

Conclusions:

• Solid-state DFT is a computationally accessible and reliable method for studying thiophene-based polymers.
• The PWC/DNP approach offers a superior alternative to force fields for predicting experimental crystal structures.
• The study validates the reported crystal structures of P3MBT and P3BT as stable configurations.