Stable thermoelectric response of SnSe thin films for low-temperature applications

Abstract Tin selenide (SnSe) is a low-cost, environmentally friendly material with outstanding thermoelectric properties. Recent studies have shown that polycrystalline SnSe can achieve a figure of merit (zT) of 3.1 at 783 K, surpassing that of its single-crystal counterpart. In this work, highly uniform, epitaxial, and (0 k 0)-oriented SnSe thin films with a thickness of approximately 70 nm were successfully fabricated via a one-step Pulsed Laser Deposition (PLD) process onto silicon dioxide (SiO 2 ) substrates. The structural and morphological properties of the films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and complementary spectroscopic techniques. The highly uniform (surface roughness of 1.3 nm) fabricated thin films exhibited an optical band gap around 0.9 eV, thus demonstrating the narrow band gap semiconductor character. Thermoelectric performance was assessed through Seebeck coefficient measurements using a custom-designed setup, with proven stability in time, upon multiple heating–cooling cycles. The films’ Seebeck coefficients were measured in the temperature range of 300 to 423 K, confirming the thermoelectric potential of these materials. These results underline the viability of PLD-grown SnSe thin films for integration into miniaturised and/or flexible thermoelectric devices, supporting the development of next-generation sustainable energy technologies.