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_1/3Nb_2/3)O₃–0.35PbTiO₃ (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 10⁵ repeated bending cycles. The developed thick-film structures also exhibit a piezoelectric coefficient d₃₃ of ∼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 °C and 300 kV cm⁻¹, which exceeds the value of 0.72 K at ∼65 °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.

The preparation of metal–ceramic layered composites remains a challenge due to the incompatibilities of the materials at the high temperatures of the co-firing process. For densification, the ceramic thick-film materials must be subjected to high-temperature annealing (usually above 900 °C), which can increase the production costs and limit the use of substrate or co-sintering materials with a low oxidation resistance and a low melting point, such as metals. To overcome these problems, the feasibility of preparing dense, defect-free, metal–ceramic multilayers with a room-temperature-based method should be investigated. In this study, we have shown that the preparation of ceramic–metal Al₂O₃/Al/Al₂O₃/Gd multilayers using aerosol deposition (AD) is feasible and represents a simple, reliable and cost-effective approach to substrate functionalisation and protection. Scanning electron microscopy of the multilayers showed that all the layers have a dense, defect-free microstructure and good intra-layer connectivity. The top Al₂O₃ dielectric layer provides excellent electrical resistance (i.e., 7.7 × 10¹² Ω∙m), which is required for reliable electric field applications.