Yong Soo Cho

Piezoelectric energy harvesters based on Pb(Zr 0.5 Ti 0.5 )O 3 (PZT) ceramics have been extensively studied for various low‐power applications. Herein, unprecedented multiple‐harvester structures with record‐breaking performance are proposed for targeting nonresonant‐frequency or extremely low‐frequency applications. Exceptional combinations of PZT with three different relaxor materials, namely, Pb(Co 1/3 Nb 2/3 )O 3 (PCN), Pb(Ni 1/3 Nb 2/3 )O 3 (PNN), and Pb(Zn 1/3 Nb 2/3 )O 3 (PZN), are systematically investigated in terms of their structural changes and piezoelectricity. Following the optimization of the PCN–PZT, PNN–PZT, and PZN–PZT systems in terms of piezoelectricity and power generation, a few device structures are designed using the advantages of each system. For example, the highest g 31 composition of 0.2PCN–0.8PZT is combined with the highest d 31 of 0.4PZN–0.6PZT to maximize the power generation in the two‐parallel‐tape structure. Multilayer harvester structures with up to four layers are also evaluated to correlate the enhanced voltage and current with the layer thickness and effective area for surface‐charge polarization. The four‐layer 0.4PZN‐0.6PZT unimorph cantilever demonstrates exceptional energy‐harvesting performance of ≈535.9 µW, corresponding to the record power density of ≈10 mW cm −2 g −2 Hz −1 at 2 Hz. The outstanding outcome is believed to be a benchmark for various nonresonant‐frequency applications.