The key role of charge carriers scattering on polar optical phonons in semiconductors for thermoelectric energy conversion

•The Boltzmann equation for charge carriers is solved by numerical procedure.•Pure and doped by donor atoms InSb is chosen as a subject of studies.•Kinetic coefficients are calculated to find the thermoelectric figure of merit.•Scattering on polar optical phonons is crucial for thermoelectric efficiency.•High values of dielectric constants are desirable for new thermoelectric materials.

The Boltzmann equation for charge carriers in n-type InSb is solved by numerical procedure. Temperature and donor atoms concentration dependences of kinetic coefficients are studied with respect to the thermoelectric energy conversion efficiency. It is found that the mechanism of the charge carriers scattering on polar optical phonons is of crucial importance for thermoelectric figure of merit of semiconductors. High thermoelectric efficiency of compounds and alloys comprising such heavy atoms as Pb or Bi is explained by weakening of the above mentioned scattering mechanism due to gigantic values of dielectric constants of substances caused by high polarizability of heavy atoms.