Electrocaloric cooling technologies for a sustainable world

Our societies are highly dependent on reliable cooling for air conditioning (AC) and refrigeration. Currently, modern cooling is supported by a 19^th century technology: vapor compression cycle (VCC)-based cooling. Refrigerants used in the VCC cooling are strong greenhouse gases and thus are among the leading causes of global warming. The electrocaloric (EC) cooling is attractive as an alternative to the VCC cooling. EC cooling is environmentally benign, compressor-free, highly scalable, and has the potential of achieving higher efficiency than VCC cooling. The active EC materials research since the late 2000s has created several EC materials that exhibit giant electrocaloric effect (ECE) (by direct measurement). These EC materials have enabled the demonstration of EC cooling devices that exhibit temperature lifts of more than 8 K. These EC materials and device research reveals the promise of ferroelectric materials in generating giant ECE at low electric fields and EC cooling devices achieving high performance. This review highlights these advances and offers perspectives of the EC cooling technologies.