The successful utilization of Pb-free piezoelectric materials is considered as critical since the piezoelectric material-based thin-film cantilever is still the preferred choice for commercial vibrational energy harvesters. Herein, we introduce a highly efficient piezoelectric energy harvester based on a Pb-free representative compound, Bi 0.5 Na 0.5 TiO 3 , which has not been explored so far. Applying a strong electric field for poling purposes brought unexpectedly huge changes in the dielectric constant and piezoelectric coefficient, which were responsible for the promising power density of 21.2 μW/cm 2 /g 2 /Hz with 537.7 mV output voltage and 2.22 μW output power for a 2 μm thick 0.94(Bi 0.5 Na 0.5 )TiO 3 -0.06BaTiO 3 thin-film cantilever. The power density value is the best so far compared with any reported values for thin-film-based harvesters. As the origin of the effects of poling, the surface potentials across the grain structure are discussed in conjunction with the defect-dipole alignment, as evidenced by the increased oxygen vacancies on the film surface under an external bias field.
Bibliographical noteFunding Information:
This work was financially supported by grants from the National Research Foundation of Korea (NRF-2016M3A7B4910151), the Industrial Strategic Technology Development Program (#10079981), the Korea Institute of Energy Technology Evaluation and Planning (No. 20173010013340) funded by the Ministry of Trade, Industry, & Energy (MOTIE) of Korea, and the Creative Materials Discovery Program by the Ministry of Science and ICT (2018M3D1A1058536).
All Science Journal Classification (ASJC) codes
- Materials Science(all)