Investigating the thermoelectric power factor of AlPbTe₂ thin film grown by thermal evaporation route

In this study, the thermoelectric properties of AlPbTe₂ thin films are investigated with a focus on the effects of post-annealing on their structural, electrical, and thermoelectric performance. X-ray diffraction (XRD) analysis reveals that the maximum peak intensity is observed after 1 h of post-annealing, with a subsequent decrease in intensity up to 3 h, while additional peaks become more prominent in the 3-hour sample, indicating enhanced polycrystallinity. Scanning electron microscope (SEM) images show grain growth and structural changes with post-annealing time, where small grains coalesce into larger grains, followed by crack formation after 3 h of annealing. Electrical conductivity increases from 320 S/cm in the as-grown sample to 545 S/cm in the 3-hour post-annealed sample, although conductivity decreases with increasing measurement temperature from 300 to 450 K, due to phonon scattering. The charge carrier concentration also increases significantly from 1.05 × 10²⁰ cm^{− 3} to 2.59 × 10²⁰ cm^{− 3} after 3 h of post-annealing, while charge carrier mobility decreases due to carrier-carrier scattering. The Seebeck coefficient is negative, confirming n-type behavior, and increases with temperature across all samples. The 1-hour post-annealed sample shows the highest Seebeck coefficient, peaking at 242 µV/K at 450 K. Finally, the thermoelectric power factor of the 1-hour post-annealed sample reaches a maximum of 24.4 µWcm^{− 1}K^{− 2} at 400 K, highlighting the improved thermoelectric performance at mid-temperatures.