Abstract
The main method for obtaining effective thermoelectric materials is the creation of micro- and macrodefects to reduce the lattice thermal conductivity coefficient, as well as doping with electroactive impurities to achieve the optimal value of the chemical potential of charge carriers η and, accordingly, the optimal concentration of charge carriers n (or p). Since the dimensionless thermoelectric figure of merit ZT is a non-monotonic function of the chemical potential of carriers, determining the optimal doping level is a relatively complex problem, which in the case of its experimental solution requires significant resources. In this work, using a model of electrical conductivity that takes into account one dominant mechanism of charge carrier scattering and a model of thermal conductivity that takes into account phonon scattering on phonons, grain boundaries and nanodefects, the optimal values of the chemical potential of carriers and their concentrations at which the ZT (η) function reaches a maximum at a given temperature are determined. The calculation was performed for lead telluride of electron and hole conductivity types, taking into account two types of carriers (major and minor) and taking into account the bipolar component of the thermal conductivity coefficient. The average values of the thermoelectric figure of merit for functionally gradient materials of n and p conductivity types in the temperature range (400-800) K were calculated.