Roles of carbon nanotube and BaTiO3 nanofiber in the electrical, dielectric and piezoelectric properties of flexible nanocomposite generators

We report the electrical, dielectric and piezoelectric properties of flexible PDMS-based nanocomposite generators, which are tunable by different contents of multi-walled carbon nanotube (MWCNT, 0.0-5.0 wt%) and BaTiO3 nanofiber (10-50 wt%). The BaTiO3 nanofiber with tetragonal structure was manufactured by an electrospinning and following calcination process. For the first series of nanocomposite generators with 30 wt% BaTiO3 nanofiber and 0.0-5.0 wt% MWCNT, both electrical and dielectric properties were dramatically enhanced at a critical MWCNT content of 0.47 wt% owing to the formation of percolating networks of MWCNT in the presence of BaTiO3 nanofibers, as verified by SEM analysis. Accordingly, the nanocomposite generator with 30 wt% BaTiO3 and 5.0 wt% MWCNT achieved the highest conductivity of 0.12 S/cm and dielectric constant of 4474 at 1 kHz, whereas the nanocomposite generator with 30 wt% BaTiO3 and 2.0 wt% MWCNT attained the best piezoelectric performance by harvesting average output voltage of ∼3.00 V, current of ∼0.82 μA, and power of ∼0.14 μW. In cases of the second series of nanocomposite generators with 2.0 wt% MWCNT and 10-50 wt% BaTiO3 nanofiber, the electrical conductivity and dielectric constant increased with the increment of BaTiO3 content up to 40 wt%. Overall, the nanocomposite generator with 2.0 wt% MWCNT and 40 wt% BaTiO3 nanofiber generated the highest average output voltage of ∼3.73 V, current of ∼1.37 μA, and power of ∼0.33 μW, which was feasible to light up commercial LEDs and to charge a capacitor after rectification, revealing the potentiality in powering self-sufficient nanodevices and wireless electronics.