Effect of Thermodynamics and Curvature on the Crystallinity of P3HT Thin Films on ZnO: Insights from Atomistic Simulations

In this work, by means of model potential molecular dynamics simulations, we correlate the polymer crystalline order to the substrate morphology by focusing on the case of thin P3HT films deposited on planar and nanostructured ZnO surfaces under room temperature conditions. We show that the polymer/ZnO adhesion is driven by the electrostatic interactions between backbones and substrates. On planar ZnO substrates, though some disorder is present, the polymer films can be crystalline with predominance of the face-on molecular orientation. In addition, by studying models of curved substrates, consisting of ZnO nanorods, we show that the local curvature induces the bending of the polymer backbones and consequent disorder in the molecular film with the possible formation of amorphous layers. The analysis of the structure factor reveals a monotonic correlation between the local curvature and the diffraction peak associated with the backbone.