Nano-architected GaN metamaterials with notable topology-dependent enhancement of piezoelectric energy harvesting
Jun Cai, Lifu Yan, Alireza Seyedkanani, Valérie Orsat, Abdolhamid Akbarzadeh
Abstract
The pursuit of efficient energy harvesting technologies at the nanoscale has prompted a thorough exploration of piezoelectric nanogenerators. This study investigates the piezoelectric properties (e.g., piezoelectric stress and strain constants, dielectric constant, and piezopotential coefficient) of nano-architected gallium nitride (GaN) metamaterials through molecular dynamics simulation. Constructing twelve different topologies from three architecture families (i.e., cubic, octahedron, and triply periodic minimal surface), the research uncovers topology-dependent enhancements in piezoelectric characteristics compared to bulk GaN. The effect of relative density on piezoelectric properties, resulting from surface effect and surface-to-volume ratio, is systematically explored. Employing density functional theory calculations, we study the intricate interplay between surface and bulk atoms, including electron density difference, and bond lengths and angles, thereby demonstrating that surface effect dictates the piezoelectric properties of GaN architected metamaterials at the nanoscale. Compared to other piezoelectric nanomaterials, we highlight the remarkably high specific piezopotential coefficients of nano-architected GaN metamaterials. This study indicates the promising potential of nano-architected GaN metamaterials for the development of efficient nanogenerators and nanoscale energy harvesters. The findings pave the way for the realization of the next generation of self-powered nanosensors, nanorobots, and microelectromechanical systems.