Cooling efficiency and losses in electrocaloric materials

A figure of merit for assessing the cooling efficiency of electrocaloric (EC) materials is defined, where the caloric properties are taken into account jointly with the material's losses. Using a specifically developed measurement setup, based on flexible thermistances, the caloric effect and the losses are directly measured on P(VDF-TrFE-CFE) electrocaloric polymer films. The data are used, jointly with our figure of merit, to extrapolate the cooling efficiency to be expected, under actual working conditions, from the studied EC material. Dielectric losses emerge as a major limiting factor for achieving the needed cooling performance. This finding shows that, beside the research for huge caloric response, material loss reduction has to be considered a key objective for researching an optimal EC refrigerant for cooling applications. Eventually, some strategies toward loss reduction are outlined.