Effect of Annealing Temperature on the Morphology and Piezoresponse Characterisation of Poly(vinylidene fluoride-trifluoroethylene) Films via Scanning Probe Microscopy

Abstract

Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE (70/30)) films were synthesized on a gold/glass substrate via spin coating. The films were annealed at a temperature between 125 ∘ C and 180 ∘ C. Nanoscale characterisation of the morphology, polarization switching, and local piezoresponse hysteresis loops of PVDF-TrFE film was studied using a scanning probe microscope (SPM). Ferroelectric switchable domains were identified by piezoresponse force microscopy (PFM) for all films. Small grains, with weak piezoresponse character, were observed for films annealed just above the Curie temperature. Acicular grains were obtained when the annealing temperature approached the melting point and the piezoresponse increased. Annealing above the melting point decreased the piezoresponse and the morphology changed dramatically into plate-like structures.

Optimization Of PVDF-TrFE Processing Conditions For The Fabrication Of Organic MEMS Resonators

“…Nevertheless, after polarization the piezoelectric response increases with annealing duration and the amplitude is much higher than without polarization, highlighting the importance of the poling step. Moreover, the results show that only a few minutes of annealing are necessary to achieve the best piezoelectric property of PVDF-TrFE, in contrast to times on the order of hours that can be found in the literature 18 19 . This result suggests that a large mobility of PVDF-TrFE chains occurs during annealing.…”

“…As described in the fabrication section, PVDF-TrFE films are annealed after spin-coating. The influence of the annealing temperature has been already studied 18 19 . According to these two references, the optimal annealing temperature must lie between the Curie temperature (135 °C according to Piezotech) and the melting temperature (150 °C).…”

Enhanced memory characteristics in organic ferroelectric field-effect transistors through thermal annealing

“…[21][22][23] Figure 3(e) shows the surface roughness of the P(VDF/TrFE) thin-films as a function of these annealing temperature. The roughness increased dramatically from 15 nm to more than 30 nm when the film was annealed at temperatures above to the melting temperature T m of 150…”

Response of P(VDF-TrFE) sensor to force and temperature

“…After spin-coating, the P(VDF-TrFE) was annealed at 120°C for three hours to remove any excess solvent from the surface and to aid with the crystallization process within the polymer material. 120°C was chosen as a suitable temperature as it sits between the P(VDF-TrFE) Curie temperature (110°C) [20] and melting temperature (150°C) [20] and maximizes the opportunity for the film to crystallize in the β-phase and thus improve the piezoelectric response of the film [20].…”