Performance Enhancement of Ca 3 Co 4 O 9 ‐based Transverse Multilayer Thermoelectric Generators for Low‐Power Applications

ABSTRACT Transverse thermoelectric generators (TTEG) enable conversion of thermal into electrical energy with perpendicular directions of the applied temperature gradient and the induced thermoelectric voltage. We report on the fabrication of transverse multilayer thermoelectric generators (TMLTEG) based on p‐type Ca 3 Co 4 O 9 (CCO) ceramic tapes and printed silver which were conventionally sintered (CS) in air at 920°C or using pressure‐assisted sintering (PAS) at 920°C and 1.5 MPa. The thermoelectric performance of TMLTEGs was evaluated using analytical calculations and simulations. The transverse thermoelectric power factor PF tr and thermoelectric figure‐of‐merit ZT tr of an artificial layered structure composed of CCO and silver were calculated and simulated as functions of layers tilt angle φ and metal‐to‐ceramic thickness ratio ν t . TMLTEG devices with various CCO layer thicknesses of 150 µm, 100 µm, or 33 µm were fabricated and cofired at 920°C in air, which exhibit power outputs of 2.3 mW, 3.2 mW, and 4.1 mW at Δ T = 160 K, respectively. TMLTEGs which were cofired using PAS show a higher power density of 16.4 mW/cm 3 at Δ T = 225 K. This enhancement in power (≈ 80%) is crucial for thermoelectric modules comprising multiple TMLTEG devices. The device measurements were compared with 3D simulations.