The ultra-high thermoelectric power factor in facile and scalable single-step thermal evaporation fabricated composite SnSe/Bi thin films

Abstract

The thermoelectric effect provides a viable route for the direct conversion of thermal to electrical energy, which helps improve energy efficiency by utilizing waste heat from conventional energy resources. Herein, we report a simple fabrication of composite SnSe/Bi thin films with superior thermoelectric performance evident by their ultrahigh power factor. The composite SnSe/Bi film is deposited on a Si/SiO₂ substrate by thermal evaporation techniques, providing a scalable and high-quality film. We have varied the weight percentage of Bi in SnSe to fabricate different samples, and a high-quality thin film is obtained, as confirmed by the SEM micrographs. The composite SnSe/Bi thin film shows n-type behavior due to the presence of different phases like BiSe, SnSe, and metallic Bi. Upon increasing Bi wt% in the composite film, the film's metallic nature increases, resulting in a decrease in the Seebeck coefficient and an increase in electrical conductivity. The maximum power factor of ∼800 μW m⁻¹ K⁻² at 580 K is observed for 25 wt% of Bi in the composite SnSe/Bi thin film comparable to single crystalline and polycrystalline SnSe. The significant increase in the thermoelectric performance of thin films paves the way for the development of self-powered wearable and internet of things (IoT) applications.