Barium calcium zirconium titanate thin film-based capacitive thermoelectric converter for low-grade waste heat

A capacitive thermoelectric device can harvest thermal energy and convert it to electrical energy by employing a temperature-dependent dielectric material whose permittivity sharply changes with temperature. Electricity can be generated by fluctuating the temperature of the capacitor. Currently, capacitive thermoelectric devices are not broadly used, which can be attributed to the low efficiency of the existing solutions, the lack of dielectric materials with suitable temperature non-linearity of the dielectric permittivity, and the complexity of modulating heat flux on the dielectric material. Here, we propose a device based on (Ba _0.85 Ca _0.15 )(Ti _0.92 Zr _0.08 )O ₃ and (Ba _0.73 Ca _0.27 )(Ti _0.98 Zr _0.02 )O ₃ thin films. It demonstrates power outputs of 0.06 mW to 0.3 mW across ΔT = 5–20 °C at 15 V bias, and a dynamic workload of an Intel E5-2630 microprocessor. These results highlight the potential of barium calcium zirconium titanate thin films to be used for a capacitive thermoelectric converter.