Effect of Electrode Structure on the Performance of Fully Printed Piezoelectric Energy Harvesters

Flexible piezoelectric energy harvesters have the potential to be used as power sources for wearable electronics. This study presents a simple printing-based fabrication process for a flexible piezoelectric energy-harvesting module with an integrated and optimized surface mount device (SMD)-based full-wave diode bridge rectifier. We investigate the effect of the electrode configuration on the energy-harvesting performance of the piezoelectric elements. Two types of piezoelectric elements are fabricated [a metal–insulator–metal (MIM) structure and an interdigitated electrode (IDE) structure] for comparison. The electrodes are inkjet printed using poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT: PSS), and the piezoelectric layer is bar-coated using poly (vinylidene-fluoride-co-trifluoroethylene) (P(VDF-TrFE)). The results show that a higher output power density can be obtained with the MIM-based energy harvester ( $7.8~\mu \text{W}$ /cm³) when compared to the IDE-based harvester (20.8 nW/cm³). Simulation results show that this is explained by the higher current output (i.e., charge generation ability) of the MIM-based structure.