Copper iodide doping on SnSe polycrystalline with enhanced thermoelectric properties

Abstract

SnSe, known for its low thermal conductivity and eco-friendly nature, is a potential medium-temperature thermoelectric (TE) material. However, its low carrier concentration has hindered achieving a high ZT value in n-type SnSe. This study reports the successful preparation of n-type polycrystalline SnSe_0.95-x(CuI)_x samples via mechanical alloying and spark plasma sintering, which significantly increased carrier concentration and introduced point defects, enhancing phonon scattering and reducing lattice thermal conductivity. Density functional theory (DFT) calculations reveals that CuI doping altered the bandgap and band degeneracy, enhancing the density-of-states effective mass and benefiting the Seebeck coefficient. The ZT value for the x = 0.03 sample reached a peak of 0.74 at 773 K, marking a significant improvement over the undoped sample. This study presents an effective approach to optimize TE properties through CuI doping, offering a stable and effective method to enhance the thermoelectric performance of n-type polycrystalline SnSe.