Colossal electrocaloric effect in an interface-augmented ferroelectric polymer

Abstract

The electrocaloric effect demands the maximized degree of freedom (DOF) of polar domains and the lowest energy barrier to facilitate the transition of polarization. However, optimization of the DOF and energy barrier—including domain size, crystallinity, multiconformation coexistence, polar correlation, and other factors in bulk ferroelectrics—has reached a limit. We used organic crystal dimethylhexynediol (DMHD) as a three-dimensional sacrificial master to assemble polar conformations at the heterogeneous interface in poly(vinylidene fluoride)–based terpolymer. DMHD was evaporated, and the epitaxy-like process induced an ultrafinely distributed, multiconformation-coexisting polar interface exhibiting a giant conformational entropy. Under a low electric field, the interface-augmented terpolymer had a high entropy change of 100 J/(kg·K). This interface polarization strategy is generally applicable to dielectric capacitors, supercapacitors, and other related applications.

Editor’s summary

Electrocaloric materials can pump heat in response to a changing electric field, which makes them useful in solid-state cooling applications. Zheng et al . discovered that a very large electrocaloric effect emerges in a terpolymer when pores are introduced with a sacrificial organic crystal with a low boiling temperature. The polymer interface around the pores has a large fraction of polarizable material, which gives rise to the large electrocaloric effect. The authors show that this porous material is stable after cycling it through an electric field 3 million times. —Brent Grocholski

Abstract

Using a sacrificial material to generate pores in a ferroelectric polymer generates a large electrocaloric effect