Effect of post-annealing on microstructure and piezoelectric properties of ZnO thin film for triangular shaped vibration energy harvester

In this paper, a triangular shaped piezoelectric vibration energy harvester (TS-PVEH) with zinc oxide (ZnO) thin films as the piezoelectric layer is reported. The effect of post-annealing temperature on the microstructure and piezoelectric performance of ZnO thin film deposited by magnetron sputtering method is investigated firstly. The results show that the optimum post-annealing temperature of 150 degrees C was the most beneficial to improve the piezoelectric properties of ZnO thin films. Four prototypes of TS-PVEH with different structure parameters are fabricated and optimized. The simulation and experiment results indicate that the height and width of the triangular structure have a significant influence on the vibration mode and the output performance of TS-PVEHs. The optimization results indicate that the third prototype has the best output performance. Its open-circuit voltage and short-circuit current are 290 mV and 1.25 mu A, respectively, when the vibration acceleration is 5 m/s(2) and the frequency is 56 Hz. Moreover, it has the highest load power density of 0.035 mu W/cm(2) when the load is 0.1 M Omega.