New Insight on the Interface between Polythiophene and Semiconductors via Molecular Dynamics Simulations

Polythiophene is considered as an effective dry adhesive and is promising to be a conductive adhesive due to its excellent properties. Here, we used steered molecular dynamics to investigate the interfacial strength between polythiophene and various semiconductors with similar structures including silicon, silicon carbide, and diamond. Energy decomposition was done to have a detailed insight into the adhesive mechanism. Particularly, we laid stress on the entropy difference of the polythiophene chain in different systems. Van der Waals interaction and electrostatic interaction both positively contributed to the adhesion between polythiophene and semiconductors, while the entropy change of polythiophene, including vibrational entropy change and conformational entropy change, weakened the adhesion to some extent. Our results indicated that the combined effect of these three factors made the adhesion between polythiophene and silicon carbide the strongest among the systems we studied. Additionally, it was found that such adhesion was scarcely influenced by temperature. This simple polythiophene-semiconductor interfacial study can help optimize the choice of the semiconductor when applying the polythiophene adhesive.