Abstract
Thermoelectric couples which consisted of p-type and n-type thermoelectric elements were directly written on glass substrates using femtosecond laser reduction of CuO/NiO mixed nanoparticles. CuO/NiO nanoparticle solution including CuO and NiO nanoparticles, ethylene glycol, and polyvinylpyrrolidone, was spin-coated on glass substrates. Then, p-type and n-type thermoelectric elements were formed by raster scanning of focused femtosecond laser pulses. After rinsing the samples into ethylene glycol and ethanol, the thermoelectric couples were fabricated on the substrates. Cu–Ni- and Cu2O/NiO-rich micropatterns were selectively formed by controlling the laser scanning speed. The Cu–Ni-based and Cu2O/NiO-based micropatterns exhibited n-type and p-type thermoelectric properties, respectively. An open-circuit voltage of the fabricated thermoelectric couple was 0.25 mV/K which was almost consistent with the estimated values using each Seebeck coefficient of the p-type and n-type thermoelectric elements. This selective direct-writing process of p-type and n-type thermoelectric materials is useful to fabricate various thermoelectric-type sensors.
