Recent progress on piezoelectric energy harvesting: structures and materials

With the rapid development of advanced technology, piezoelectric energy harvesting (PEH) with the advantage of simple structure, polluted relatively free, easily minimization, and integration has been used to collect the extensive mechanical energy in our living environment holding great promise to power the self-sustainable system and portable electronics. In this paper, attempts have been made to review the progress of piezoelectric materials and devices used for energy harvesting. The review focused on three parts: structure of piezoelectric devices (cantilever, cymbal, and stacks); theoretical mode, including vibration mode (d₃₁ and d₃₃) and its responding theories of different devices; and piezoelectric materials, among which the electric performance of Pb(ZrTi)O₃-based, lead-free-based, and composites applied in bulk/micro/nano-PEH devices were introduced in details. It is suggested that a new structure of PEH should be designed by combining advantages of cantilever, stacks, and cymbal structure. Besides, high d₃₃ × g₃₃ value and low ε of piezoelectric materials are required in order to generate high electric output power for bulk/micro/nano-PEH. Additionally, lead-free piezoelectric ceramics is a candidate for manufacturing PEH devices, and nano-composite materials should be developed to further improve the flexibility of piezoelectric materials. [Figure not available: see fulltext.]