3d Printing of Flexible Ga-Doped Zno Films for Wearable Energy Harvesting Applications: Thermoelectric and Piezoelectric Nanogenerators

Abstract

3D printing of energy harvesters using earth-abundant and non-toxic elements enables market competitiveness. The semiconducting behavior and non-centrosymmetric wurtzite crystal structure of Ga-doped Zinc Oxide (GZO) films are attractive for thermoelectric and piezoelectric nanogenerators. This work examines the thermal, structural, mechanical, thermoelectric, and piezoelectric properties of 3D-printed GZO nanocomposite films based on photocurable resin and GZO nanoparticles. TGA analysis revealed the thermal stability of nanocomposite film from room temperature to 230°C for safe application in wearable energy harvesters. XRD analysis disclosed the crystallinity of nanocomposite film having diffraction peaks consistent with ZnO hexagonal wurtzite structure peaks. SEM-EDS analysis showed the nanocomposite film with a bulk-like microstructure and a homogenous elemental distribution. XPS analysis confirmed the development of nanocomposite film from multiphase constituents combining Ga 2p, Zn 2p, O 1s, and C 1s core levels. C-AFM analysis identified the nanocomposite film as having a fine granular structure and conductive domain compared to the neat resin film. The GZO nanofillers tailor the stress-strain behavior and lead to flexibility enhancements of nanocomposite film. The developed photocurable resin-GZO nanocomposite film exhibited a thermoelectric power factor of 261nW/m.K2 at room temperature and piezoelectric power densities of 591nW/cm2 and 207nW/cm2 at bending and tapping deformations.

Keywords: 3D printing, Thermoelectric, Piezoelectric, Ga-ZnO, Flexible, Energy harvesting.