Pyroelectric Nanogenerators for Harvesting Thermoelectric Energy

TLDR

Thermoelectric harvesting normally relies on the Seebeck effect, but in spatially uniform temperature environments the pyroelectric effect—spontaneous polarization in anisotropic solids driven by time‑varying temperature—is required. The study demonstrates the first use of pyroelectric ZnO nanowire arrays to convert heat into electricity. ZnO nanowires generate a polarization electric field and charge separation along their length due to temperature‑dependent pyroelectric and semiconducting coupling. The nanogenerator shows stable operation with a heat‑to‑electric conversion coefficient of ~0.05–0.08 Vm²/W, indicating potential for powering nanodevices with waste heat.

Abstract

Harvesting thermoelectric energy mainly relies on the Seebeck effect that utilizes a temperature difference between two ends of the device for driving the diffusion of charge carriers. However, in an environment that the temperature is spatially uniform without a gradient, the pyroelectric effect has to be the choice, which is based on the spontaneous polarization in certain anisotropic solids due to a time-dependent temperature variation. Using this effect, we experimentally demonstrate the first application of pyroelectric ZnO nanowire arrays for converting heat energy into electricity. The coupling of the pyroelectric and semiconducting properties in ZnO creates a polarization electric field and charge separation along the ZnO nanowire as a result of the time-dependent change in temperature. The fabricated nanogenerator has a good stability, and the characteristic coefficient of heat flow conversion into electricity is estimated to be ∼0.05-0.08 Vm(2)/W. Our study has the potential of using pyroelectric nanowires to convert wasted energy into electricity for powering nanodevices.