Enhanced electrocaloric strength in P(VDF-TrFE-CFE) by decreasing the crystalline size

Through the modulation of the dipolar entropy under an applied electric field (E), a reversible temperature change (ΔT) could be achieved in a dielectric material, which is known as the electrocaloric (EC) effect. Among all EC materials, ferroelectric terpolymer P(VDF-TrFE-CFE) has been regarded as one of the most promising EC materials owing to its large EC effect and superior thermal stability. Yet, the low EC strength limits the application of terpolymers in realistic cooling devices. In this work, using the thermal treatment of quenching and low-temperature annealing, the terpolymers with significantly decreased crystalline size are prepared with their EC performances investigated. Compared to the normal ones, the terpolymers with smaller crystalline size exhibit substantially enhanced EC strength. The better EC performance may be mainly attributed to the lower energy barriers for dipole orientation, which gives rise to higher polarization at low electric fields. This work emphasizes the critical role of crystalline size on the macroscopic properties of EC polymers.