Multifunctional flexible ferroelectric thick-film structures with energy storage, piezoelectric and electrocaloric performance

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(Mg1/3Nb2/3)O-3-0.35PbTiO(3) (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(-3). 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(5) repeated bending cycles. The developed thick-film structures also exhibit a piezoelectric coefficient d(33) of & SIM;80 pm V-1. 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 & DEG;C and 300 kV cm(-1), which exceeds the value of 0.72 K at & SIM;65 & DEG;C and 60 kV cm(-1) 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.