All-Atom Molecular Dynamics Simulation of Temperature Effects on the Structural, Thermodynamic, and Packing Properties of the Pure Amorphous and Pure Crystalline Phases of Regioregular P3HT

Abstract

Molecular dynamics simulations have been carried out to probe chain self-organization and structure in regioregular poly-3-hexylthiophene (Rr-P3HT). Taking into account recent experimental findings that provide evidence for a semicrystalline ordering in P3HT where crystalline lamellae are periodically separated by interlamellar amorphous zones, we have separately simulated the pure crystalline and the pure amorphous phases of Rr-P3HT, and studied the dependence of their conformational and configurational properties on temperature (from 225 to 600 K). All simulations have been carried out with the very accurate, all-atom Dreiding force-field. In the pure crystalline phase, the system is found to adopt a noninterdigitated and tilted structure irrespective of temperature and chain molecular weight (Mw) consistent with the results of XRD measurements and other theoretical works. Increasing the temperature did not seem to dramatically affect the interchain distance inside the crystal. Temperature therefore sho...