Post-selenization induced structural phase transition and enhanced thermoelectric properties in AgBiSe2 alloy thin films

Thermoelectric materials have the potential to harness waste heat for energy purposes, and there is considerable scientific and technological interest in managing their thermal properties. BiAgSe2, a narrow bandgap semiconductor, is a strong candidate for use as a thermoelectric material due to its remarkably low thermal conductivity. The compound of AgBiSe2 crystallizes in the hexagonal symmetry of the grown sample at room temperature and transitions to a cubic phase, increasing the post selenization duration at 773K. The granular surface morphology has been observed and slightly decreases with increases the more post selenization treatment. The enhancement of the Seebeck coefficient value from 126 to 177 μV/K due to the phase transition, grain refinement and post-selenization treatment. The improvement of charge carrier concentration and electrical conductivity is due to improving the crystallinity and diffusion of Se atoms in the AgBiSe2 alloy thin film with post-selenization time. The maximum thermoelectric power factor (5.16 μWcm−1K−2) of stable cubic AgBiSe2 alloy thin film has been achieved at room temperature. However, the stable cubic phase of the AgBiSe2 alloy thin film exhibits excellent thermoelectric behaviour, making it a promising material for applications in thermoelectric devices.