Hot Plate Annealing at a Low Temperature of a Thin Ferroelectric P(VDF-TrFE) Film with an Improved Crystalline Structure for Sensors and Actuators

Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

[1]  Guo-Rong Li,et al.  Pyroelectric Coefficient and Heat Capacity of a Ferroelectric Copolymer of Vinylidene Fluoride and Trifluoroethylene at Low Temperatures , 1992 .

[2]  A. Kingon,et al.  Activated Solutions Enabling Low‐Temperature Processing of Functional Ferroelectric Oxides for Flexible Electronics , 2014, Advanced materials.

[3]  K. Kim,et al.  Spectroscopic analysis of the electric field induced structural changes in vinylidene fluoride/trifluoroethylene copolymers , 1989 .

[4]  T. Furukawa,et al.  Piezoelectricity and pyroelectricity in polymers , 1988, 6th International Symposium on Electrets,(ISE 6) Proceedings..

[5]  M. Litt,et al.  Poly(Vinylidene Fluoride). , 1977 .

[6]  Hari Singh Nalwa,et al.  Ferroelectric Polymers : Chemistry: Physics, and Applications , 1995 .

[7]  I. Lazareva,et al.  Interface screening and imprint in poly(vinylidene fluoride/trifluoroethylene) ferroelectric field effect transistors , 2009 .

[8]  V. G. Chigrinov,et al.  Properties of the Materials , 1994 .

[9]  T. Furukawa.  Ferroelectric properties of vinylidene fluoride copolymers , 1989 .

[10]  A. Kholkin,et al.  First principle calculations of molecular polarization switching in P(VDF–TrFE) ferroelectric thin Langmuir–Blodgett films , 2007 .

[11]  K. Tashiro,et al.  Molecular Vibrations of Three Crystal Forms of Poly(vinylidene fluoride) , 1975 .

[12]  Takeshi Yamada,et al.  Ferroelectric properties of vinylidene fluoride‐trifluoroethylene copolymers , 1981 .

[13]  W. C. Gan,et al.  Effect of TiO2 on enhanced pyroelectric activity of PVDF composite , 2014 .

[14]  K. Kim,et al.  Spectroscopic analysis of the crystalline and amorphous phases in a vinylidene fluoride/trifluoroethylene copolymer , 1989 .

[15]  Mary Anne White,et al.  Properties of Materials , 1999 .

[16]  A. J. Lovinger,et al.  Crystallographic changes characterizing the Curie transition in three ferroelectric copolymers of vinylidene fluoride and trifluoroethylene: 2. Oriented or poled samples , 1983 .

[17]  B. Gnade,et al.  Ferroelectric Properties and Polarization Switching Kinetic of Poly (vinylidene fluoride-trifluoroethylene) Copolymer , 2011 .

[18]  A. J. Lovinger,et al.  Structural and Dielectric Investigation on the Nature of the Transition in a Copolymer of Vinylidene Fluoride and Trifluoroethylene (52/48 Mol %). , 1982 .

[19]  Hari Singh Nalwa,et al.  RECENT DEVELOPMENTS IN FERROELECTRIC POLYMERS , 1991 .

[20]  M. Calzada,et al.  Aqueous solutions for low-temperature photoannealing of functional oxide films: reaching the 400 °C Si-technology integration barrier. , 2011, Journal of the American Chemical Society.

[21]  M. Calzada,et al.  Metal complexes with N-methyldiethanolamine as new photosensitive precursors for the low-temperature preparation of ferroelectric thin films , 2011 .

[22]  R. Gregorio,et al.  Effect of crystalline phase, orientation and temperature on the dielectric properties of poly (vinylidene fluoride) (PVDF) , 1999 .

[23]  J. M. Kometani,et al.  The role of molecular defects on the structure and phase transitions of poly(vinylidene fluoride) , 1987 .

[24]  R. Gregorio,et al.  Morphology and phase transition of high melt temperature crystallized poly(vinylidene fluoride) , 2000 .

[25]  G. Minas,et al.  Improving the optical and electroactive response of poly(vinylidene fluoride–trifluoroethylene) spin-coated films for sensor and actuator applications , 2012 .

[26]  Bruce E. Gnade,et al.  Optimization of poly(vinylidene fluoride-trifluoroethylene) films as non-volatile memory for flexible electronics , 2010 .