Influence of microstructure and thermoelectric properties on the power density of multi-walled carbon nanotube/ metal oxide hybrid flexible thermoelectric generators

The quest for a low-cost, flexible thermoelectric generator using eco-friendly metal oxide-based materials for low-temperature applications has motivated this work. The work compares the performance of amine-functionalized multi-walled carbon nanotubes (MWCNT-NH₂) and metal oxide nanoparticles (CuO, NiO, and Fe₂O₃) ink-based hybrid flexible thermoelectric generators. Study reveals that the thermoelectric performance of a flexible thermoelectric generator improves by fine-tuning the materials crystallite size, bandgap, carrier concentration, carrier mobility, resistivity, the Seebeck coefficient, and micro-porosity of the ink film, which could be materialized by using hybrid thermoelectric materials. Among the three fabricated devices, MWCNT-NH₂/NiO hybrid flexible thermoelectric generator exhibits a maximum power output of 1.44 nW at ΔT= 100 °C. The maximum power density displayed by MWCNT-NH₂/NiO hybrid device is 59.3 nW/cm² at ΔT= 100 °C, which is 23.28% and 332.8% higher than that of MWCNT-NH₂/CuO and MWCNT-NH₂/Fe₂O₃-based devices, respectively. The performance of MWCNT-NH₂/NiO is comparatively superior to some previously reported works.