(558bw) Synthesizing Crystalline Silver Selenide Nanostructured Thin Films for Thermoelectric Applications

Silver Selenide (Ag₂Se) is a promising n-type candidate for thermoelectric applications. Nanostructured Ag₂Se reduces the thermal conductivity and increases Seebeck coefficient due to the grain boundaries between the nanoparticles. In contrast to the current complex and expensive methods of synthesizing Ag₂Se nanoparticles, our group is fabricating nanostructured Ag₂Se thin films via a simple soaking technique. Starting from amorphous-phase selenium (a-Se) thin films as templates, crystalline Ag₂Se thin films were created by soaking our a-Se thin films into a Ag⁺ ion solution, followed by an annealing step to convert the amorphous phase to the crystalline phase. The thermoelectric properties and morphology of Ag₂Se thin films are determined via Seebeck coefficient and electrical conductivity measurements, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The fabrication process is safe, low-cost, and efficient, facilitating the scale-up to production, compared to other ways of synthesizing Ag₂Se nanoparticles, such as Schlenk line synthesis. If the thermoelectric performance of Ag₂Se thin films reaches a target figure of merit (ZT) over 1, flexible Ag2Se thin films will be great candidates for use in thermoelectric devices to power miniature electronics and sensors, which have been an increasingly popular and rapidly expanding market. Most importantly, this method of template nanostructures provides a framework for exploring a wide range of other thermoelectric materials beyond Ag₂Se thin films.