Power-generation performance of lead-free (K,Na)NbO3 piezoelectric thin-film energy harvesters

We fabricated piezoelectric energy harvesters with lead-free (K,Na)NbO3 (KNN) thin films and compared their power-generation performance with that of Pb(Zr,Ti)O3 (PZT) thin film energy harvesters. The KNN and PZT thin films were deposited on Pt/Ti/Si substrates by rf-magnetron sputtering. The transverse piezoelectric properties of the KNN and PZT films were essentially the same, e31,f ∼ −11 C/m2. The peak average output power of the unimorph cantilevers of KNN/Si and PZT/Si were 1.1 and 1.0 μW, respectively. Thus, the performance of lead-free KNN thin films as a piezoelectric energy harvester is comparable to that of PZT films.