Advanced Materials Technologies
Supramolecular organic ferroelectrics have unique properties related to plasticity and freedom of design but the extensive post-deposition treatments that are typically required to achieve saturation polarization limit their applicability. A possible solution is to pre-align the molecules. Here, the
effect of dip-coating on the pre-alignment of the prototypical supramolecular ferroelectric trialkylbenzene-1,3,5-tricarboxamide (BTA) and the resulting changes in the ferroelectric switching behavior of the resulting thin films
are analyzed. Dip-coated films are characterized by different BTA concentrations and dip-coating velocities. Landau–Levich and evaporation regimes are identified. The corresponding ferroelectric switching behavior is investigated and reveals that dip-coating in general enhances the ferroelectric switching of pristine films. Dip-coating perpendicular to the electrodes (parallel to the electric field direction) has the most significant effect, and without further alignment steps, leads to equal switching behavior as films that are aligned by post-deposition treatment, that is, field annealing. The results are expected
to be transferable to other small molecular ferroelectrics.
5. Experimental Section
… Dip-coating and Film Characterization: For dip-coating, the substrates
were placed between automated tweezers and were dip-coated in a
roughly 1 cm high vial by immersing them for around 7–8 mm.
The vial was filled to the top to reduce the effect of the surrounding atmosphere
getting saturated with the evaporating solvent. The dip-coating process was steered by the software, which came with the used Nadetech Innovations ND-DC Dip Coater. The immersion speed was set to 100 mm min−1. The down position was chosen so that the substrate does not reach the bottom of the vial. After immersion, a down waiting time of 20 s was applied.
Keywords: Dip-coating; Double wave method; Ferroelectric switching;