Piezoelectric Energy Harvesting from Two-dimensional Boron Nitride Nanoflakes.

Two-dimensional piezoelectric hexagonal boron nitride nanoflakes (h-BN NFs) were synthesized by a chemical exfoliation process and transferred onto an electrode line-patterned plastic substrate to characterize the energy harvesting ability of individual NF by external stress. A BN single NF produced the alternate piezoelectric output source of ~50 mV and ~30 pA when deformed by mechanical bendings. The piezoelectric voltage coefficient (g11) of a BN single NF was experimentally determined to be 2.35 × 10-3 V·m·N-1. The piezoelectric composite composed of BN NFs and an elastomer was spin-coated onto a bulk Si substrate and then transferred onto the electrode-coated plastic substrates to fabricate a BN NFs-based flexible piezoelectric energy harvester (f-PEH) which converted the piezoelectric voltage of ~9 V, current of ~200 nA, and effective output power of ~0.3 μW. This result provides a new strategy for precisely characterizing the energy generation ability of piezoelectric nanostructures and for demonstrating the f-PEH based on 2D piezo-materials.