Lead-free piezoelectric nanowire-nanocellulose hybrids for flexible energy harvesters (Nanoflex)

The aim of the project “Nanoflex“ is to develop a novel piezoelectric energy harvester based on (Al,Sc)N nanowires as a lead-free and environmentally friendly alternative to conventional devices. This project, funded equally by German (DFG) and French (ANR) founding agencies, is a lively symbiosis of the scientific disciplines of materials science, physics, chemistry and device engineering. At PDI, we focus on the large-scale epitaxy of novel III-nitride nanowires on metallic TiN substrates, with the main goal to boost their piezoelectric response. This is achieved by adding Sc into the hexagonal wurtzite crystal structure of AlN without deteriorating its crystalline quality. The resulting (Al,Sc)N nanowires exhibit piezoelectric coefficients up to five times greater than binary AlN and offer additional functionalities, such as their use on flexible substrates. We analyze the effect of Sc addition on the (Al,Sc)N materials properties by advanced structural, optical and piezoelectric characterization at both the micro- and nanoscale. The identification of these structure-property relationships is crucial for the analysis of the device physics, fabricated and measured by the French partners.