Improving Power Factor of Multi-walled Carbon Nanotube Fibers through Laser Exposure

Abstract

In the present study, we have modified multi-walled carbon nanotube (MWCNT) fibers using a high-power visible laser beam (∼532 nm) with a pulse energy density of ∼0.48 mJ/cm² under ambient conditions. The laser-irradiated fibers exhibited significant improvement in electrical conductivity with a minimal impact on the Seebeck coefficient. The optimally irradiated fibers (50 s exposure time) showed the highest power factor of ∼65 μW/mK² near room temperature, representing an enhancement of nearly 56% compared to pristine fibers. Detailed characterization revealed that the rapid temperature rise of samples on laser exposure leads to defect annihilation, removal of amorphous carbon, and improved alignment of MWCNTs within the fiber. These modifications collectively contribute to the improvement in the thermoelectric performance and fracture strength of laser-irradiated samples. The present scalable approach of improving the thermoelectric and mechanical properties of MWCNT fibers through laser beam exposure holds great promise for wearable thermoelectric applications.