Photothermoelectric Device Based on Near‐Infrared Absorption and Reflection of Transparent Conductive Oxides

Abstract A novel transparent photothermoelectric device has been developed, leveraging the advantageous thermoelectric properties of transparent conductive oxide thin films such as aluminium‐doped zinc oxide (AZO), and the absorption or reflectance properties of indium thin oxide (ITO) for near‐infrared (NIR) radiation. AZO exhibits transmittance exceeding 70% across a broad range of wavelengths (400–2200 nm) and a high Seebeck coefficient (120–150 µV K −1 ). Through heat treatments between 300 and 500 °C, ITO's NIR absorption is optimized to values above 40% in the 1–1.5 µm range. The optimized thickness of the ITO/Ag/ITO multilayer structure has an 80% reflectance for wavelengths above 1.2 µm. Integrating these two layers on a transparent thermoelectric AZO film creates a thermal gradient induced by infrared (IR) radiation. This gradient results in a photothermal potential that is sensitive to sunlight intensity, with a sensitivity measured at 1.5 mV W −1 . This innovation marks a significant advancement in technology, showcasing the potential for transparent devices in smart windows.