Thermally Stimulated Current Study and Relaxation Behaviour of Annealed Copolymer P(VDF-TrFE) Films for Potential Pyroelectric Energy Harvesting

• Published in: Journal of electronic materials 2020-09, Vol.49 (9), p.5585-5599
• Main Authors: Ahmad, N., Majid, W. H. Abd, Halim, N. A.
• Format: Article
• Language: English
• Subjects: Annealing; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copolymers; Crystal structure; Crystallinity; Curie temperature; Depolarization; Dielectric properties; Electrical properties; Electronics and Microelectronics; Energy harvesting; Ferroelectricity; Figure of merit; Instrumentation; Kinetic theory; Materials Science; Melting points; Optical and Electronic Materials; Phase transitions; Polarization; Pyroelectricity; Solid State Physics; Spin coating; Thermally stimulated current; Thickness; Thin films
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-020-08297-2

The effects of annealing treatment on the polarization of copolymer P(VDF-TrFE) free-standing films were thoroughly studied by the thermally stimulated current (TSC) method using decomposition analysis and first-order kinetic theory. The TSC measurement mainly revealed three depolarization peaks, which are known as the β , α and Curie mode ( ρ ) peaks in P(VDF-TrFE). The origin of the TSC peaks and their relaxation behaviour were correlated with structural, morphological and electrical properties such as ferroelectricity, dielectricity and pyroelectricity. Spin-coated copolymer thin films with thicknesses of 300 nm were also prepared from 5 wt.% solutions. Both free-standing and thin films were initially annealed in the range of their Curie temperature up to the melting point [80–140°C] to increase their crystallinity. A remnant polarization current of 76.7 mC m −2 , which gives a pyroelectric coefficient of 31 μ C m −2 K −1 and a figure of merit F D of 86 μ C m −2 K −1 (1 kHz), was obtained from the sample annealed at 100°C, where the percentage of crystallinity was maximum and the phase was about to transition from ferroelectric to paraelectric.