Thermoelectric conversion and regulatory mechanism of nanoscale structures based on piezoelectric effect

In the context of growing global energy shortages and the urgent need for energy conservation and emission reduction, the conversion of waste heat into electrical energy has gradually become an important scientific issue of common concern in both academia and industry. Thermoelectric materials based on the Seebeck effect can achieve direct heat-to-electric energy conversion, but improving their conversion efficiency has always been a major challenge due to the complex coupling relationships of the involved parameters. Piezoelectric materials can directly convert different forms of mechanical energy into electrical potential. Based on the pyroelectric effect, piezoelectric materials can also directly convert thermal energy into electrical energy, but this relies on temperature changes over time, making it impossible to achieve heat-to-electric energy conversion under a constant temperature difference. In recent years, a series of thermally driven periodic motions at the micro- and nanoscale have been discovered. This provides an opportunity for realizing piezoelectric energy conversion driven by heat under a constant temperature difference. This paper introduces two mechanisms for thermally driven piezoelectric energy conversion that can generate significant output voltages under a constant temperature difference. These thermoelectric conversion mechanisms bypass the parameter coupling relationships typical of traditional thermoelectric effects, with their energy conversion efficiency depending solely on the vibration frequency of the piezoelectric materials under thermal driving, offering broad application prospects.