Direct characterization of the electrocaloric effects in thin films supported on substrates

We report a direct characterization of the electrocaloric (EC) effect in thin films clamped on substrates using micro-thermometers integrated onto the substrates. The measured temporal temperature profiles are analyzed using a 3D heat diffusion model to extract the adiabatic temperature changes. Thin-film thermometers with very different temperature coefficients of resistance are used to verify that experimental errors due to electric or electromagnetic coupling are negligible. Our approach captured asymmetry between the electrocaloric heating and cooling due to hysteresis and yielded adiabatic temperature changes that are consistent with the existing data on free-standing ter- and co-polymer films of similar compositions.