Instability and Pattern Formation Induced in Thin Crystalline Layers of a Conducting Polymer P3HT by Unstable Carrier Films of an Insulating Polymer

We investigate the stability, self-organized morphology, and kinetics of dewetting in a thin polymer bilayer (similar to 100 nm) of P3HT/polystyrene (PS) supported on Si wafers. The thin film of the conducting polymer, P3HT or regioregular poly(3-hexylthiophene), is driven to microstructure formation by dewetting of the unstable PS underlayer. Eventually, dewetting results in the formation of an undulating P3HT conducting skin covering the isolated islands of PS. The characteristic length scale of the structure is linearly proportional to the thickness of the PS underlayer. The kinetics of hole growth shows that the slippage behavior of the P3HT/PS bilayer which is different from the no-slip seen without the presence of the P3HT over layer. The bending elasticity and slippage induced by confinement of the PS layer by the P3HT layer strongly influence the length scale and kinetics of the dewetting process.