Sadl M., Prah U., Kovacova V., Defay E., Rojac T., Lebar A., Valentinčič J., Ursic H.
Journal of Materials Chemistry C, vol. 11, n° 29, pp. 10058-10068, 2023
As a major challenge, sustainable energy management and energy self-sufficiency require microsystems that manage multiple energy operations in a single device. In this work, flexible thick-film structures with promising energy storage and electrocaloric cooling capabilities as well as piezoelectric properties are developed. The functional thick-film layer is based on relaxor-ferroelectric 0.65Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-0.35PbTiO<sub>3</sub> (PMN-35PT) directly deposited on a flexible polyimide substrate by an aerosol deposition method. The thick-film structures exhibit a promising recoverable energy-storage density of 10.3 J cm<sup>−3</sup>. After extensive bending tests, the structures showed no signs of degradation. The high bendability and durability are confirmed by stable energy storage properties after bending up to a radius of 1.5 mm (2.4% bending strain) and 10<sup>5</sup> repeated bending cycles. The developed thick-film structures also exhibit a piezoelectric coefficient d<sub>33</sub> of ∼80 pm V<sup>−1</sup>. Using two direct electrocaloric measurement methods, we demonstrated that the electrocaloric temperature change in the prepared PMN-35PT thick-film structures reaches a maximum of 0.87 K at 63.5 °C and 300 kV cm<sup>−1</sup>, which exceeds the value of 0.72 K at ∼65 °C and 60 kV cm<sup>−1</sup> reported for bulk ceramics of the same composition. The PMN-35PT thick films prepared here are thick-film structures with excellent flexibility, promising for future multifunctional microsystems that manage multiple energy operations, enabling comprehensive energy harvesting, storage and conversion to thermal energy.
