Lead‐Free Pyroelectric Materials for Thermal Energy Harvesting: A Comparative Study

AbstractThe thermal energy harvesting potential of different pyroelectric materials including Sr0.5Ba0.5Nb2O5(SBN), [Bi0.48Na0.4032K0.0768] Sr0.04(Ti0.975Nb0.025)O3(BNT‐Nb), Ba0.85Sr0.15Zr0.1Ti0.9O3(BST‐BZT), Ba0.85Ca0.15Zr0.1Ti0.9O3(BCT‐BZT), and Ba0.9Ca0.1TiO3(BCT) ceramics is compared. Amongst these materials, BCT is found to be best for pyroelectric energy harvesting. Open‐circuit voltages were found to be 1.7 V, 500 mV, 650 mV, 600 mV, and 400 mV for BCT, SBN, BCT‐BZT, BST‐BZT, and BNT‐Nb, respectively. BCT is further analyzed, revealing an optimum power output of 0.072 μW at the optimized cycle frequency (0.06 Hz) and at a load resistance of 18 MΩ. To improve the effectiveness of energy conversion from heat to electricity, the synchronized switch harvesting on inductor (SSHI) technique is experimentally tested on a BCT sample. It is revealed that this concept based on SSHI can significantly increase the amount of power extracted from pyroelectric materials. Compared with 0.072 μW across a standard circuit in a BCT sample, an enhanced power output of 0.16 μW and 0.14 μW is obtained using parallel and series SSHI, respectively at 0.06 Hz. The results reveal that the non‐linear processing technique based on SSHI leads to significant power improvement compared to non‐switched interface.