For a type-1 piezoelectric energy harvester (PEH), in which stress develops in the supporting system of the piezoelectric materials, the electromechanical coupling factor (kij) of the piezoelectric materials is important for the output power at the resonance frequency. Therefore, soft-piezoelectric materials are good candidates for these PEHs. For type-2 PEHs, in which stress develops in the piezoelectric material and supporting system, the figure of merit (FOM) of the output power at the resonance frequency is (kij 2 × Qm)/s11 E, where Qm and s11 E are the mechanical quality factor and the elastic compliance of piezoelectric materials, respectively. In particular, the effect of Qm is very large for these PEHs, indicating that hard-piezoelectric materials are good candidates for type-2 PEHs operating at the resonance frequency. For both type-1 and type-2 PEHs operating at off-resonance frequency, the kij 2 × dij × gij is the FOM of the output power of the PEHs, where gij is a piezoelectric voltage constant. Therefore, soft-piezoelectric materials are also good candidates for both type-1 and type-2 PEHs operating at the off-resonance frequency.
- Piezoelectric materials
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Electrical and Electronic Engineering