Coupling Enhancement of Photo-Thermoelectric Conversion in a Lateral ZnO Nanowire Array

Scavenging sustainable energy from surroundings by the photothermoelectric effect has attracted considerable attention along with the growing crisis of energy security. The cross interaction between heat and light is important for understanding the photothermoelectric mechanism. Herein, we demonstrate a photothermoelectric device based on an undoped ZnO nanowire array with a lateral structure. The output of the ZnO nanowire array depends linearly on the position of the light spot with zero output for the light spot in the center, achieving a power factor of 85 μW m–1 K–2 at room temperature. A coupling enhancement (″1 + 1 > 2″) of photothermoelectric conversion is observed in the ZnO device. To reveal the intrinsic mechanism, the cross interaction between heat and light was investigated under various working conditions. Under a temperature gradient of 12.5 K, the output current and voltage of the lateral ZnO device under 227.4 mW/cm2 light illumination are enhanced by 67.2% and 10.9%, respectively. This study reveals the cross interactions in the process of photothermoelectric conversion and might have guiding significance in solar energy harvesting applications.