Investigation of the electrocaloric effect in ferroelectric polymer film through direct measurement under alternating electric field

Abstract

The electrocaloric (EC) effect of ferroelectric polymer film was investigated at a high frequency. The analysis used the finite element method and revealed that the extractive heat density per unit of time increases and the thermal diffusion length decreases with an increase in the frequency of the driving electric field. Given the small thermal diffusion coefficient of ferroelectric polymers, the high-frequency drive of the EC effect for ferroelectric polymer film is promising for cooling devices. To discuss the EC effect under an alternating current (AC) electric field, the EC temperature change of the vinylidene fluoride-trifluoroethylene copolymer 75/25 P(VDF-TrFE) film with a thickness of 2 μm was characterized through direct measurement using a thin-film thermocouple. The EC temperature change increases with an increase in the electric field and frequency and reached up to 0.23 °C at 1.5 MV cm−1 and 10 kHz. The extractive heat density was estimated to be as high as 0.69 W cm−2.