The coordination of thermoelectric and photoelectric effects through tailoring the heat-driven electric field revealed by a “ship-lock”-based thermoelectric material

Abstract

The thermoelectric materials could play a crucial role in fuel production for a circular economy, as they could provide a method to utilize the photons of relatively low energy from thermalization losses of light absorption. However, the traditional thermoelectric property was enhanced through optimizing the inherent band engineering according to the Seebeck coefficient, which ignored the off-centering behavior of the conduction band under the light. Herein, we exploited the thermal conversion characteristics of covalent organic framework-1,3,5-triformylphloroglucinol 3,8-diamino-6-phenylphenanthridine (COF-TpDPP) under red light to construct a three-component photoelectric material (WO₃/COF-TpDPP/CdS). Through the Kelvin probe force microscope and density functional theory calculations, the COF-TpDPP layer reduced carrier transport barriers under the illumination of red light through the off-centering behavior of the conduction band to form thermoelectric and band-gap compression effects. As a result, the COF-TpDPP facilitated carrier transport between WO₃ and CdS by utilizing its thermoelectric properties to reconstruct the carrier migration pathway, thereby creating a heat-mediated charge transfer system analogous to a “ship-lock” mechanism, which caused a 30% enhancement in photocurrent. Additionally, the photocatalytic degradation capability of WO₃/COF-TpDPP/CdS has been utilized to develop a device for measuring soluble total organic carbon. This new mechanism presents approaches for the design of advanced thermoelectric materials in enhancing photo-electrocatalytic efficiency for the application in energy management, the treatment of hazardous waste, and environmental monitoring.