Enhanced Thermoelectric Performance of Bi0.5Sb1.5Te3 through Precise Pb Doping: Analysis Using the Single Parabolic Band Model

초록

This study investigates the thermoelectric properties of Pb-doped p-type Bi0.5Sb1.5Te3 alloys usingthe Single Parabolic Band (SPB) model, focusing on optimizing room-temperature performance. Wesystematically analyze the effects of Pb doping (0, 0.49, 0.65, 0.81, 0.97, and 1.3 at%) on key parametersincluding density-of-states effective mass (md*), non-degenerate mobility (μ0), weighted mobility (μW), andthe thermoelectric quality factor (B-factor) at 323 K. The results reveal that md* reaches a maximum of1.37 me at 0.97 at% Pb doping, representing a 22.25 % increase over the pristine sample. The highest μ0of 234.5 cm2 V-1 s-1 is achieved at 0.65 at% Pb, highlighting the complex relationship between doping andcarrier mobility. Notably, 0.97 at% Pb doping optimizes thermoelectric performance, yielding the highestμW, power factor, and B-factor. This composition also minimizes lattice thermal conductivity (κl) by 44.93% compared to the undoped sample, significantly reducing phonon heat conduction. The Callaway-vonBaeyer model corroborates these findings, indicating maximized point defect scattering at 0.97 at% Pb. Atheoretical peak figure-of-merit (zT) of 1.74 is thus predicted at this doping level, demonstrating a possiblesubstantial enhancement in thermoelectric efficiency upon appropriate carrier concentration tuning. Theobserved trends in Seebeck coefficient, Hall carrier concentration, and Hall mobility with increasing Pbcontent provide insights into the underlying mechanisms of performance enhancement. This comprehensivestudy highlights the critical role of precise Pb doping in optimizing the thermoelectric properties ofBi0.5Sb1.5Te3 alloys for room-temperature applications and establishes a framework for future investigationsinto similar material systems.

키워드