Thermoelectric conversion efficiency in IV-VI semiconductors with reduced thermal conductivity

Abstract

Mid-temperature thermoelectric conversion efficiencies of the IV-VI materials were calculated under the Boltzmann transport theory of carriers, taking the Seebeck, Peltier, and Thomson effects into account. The conversion efficiency was discussed with respect to the lattice thermal conductivity, keeping other parameters such as Seebeck coefficient and electrical conductivity to the same values. If room temperature lattice thermal conductivity is decreased up to 0.5W/mK, the conversion efficiency of a PbS based material becomes as high as 15% with the temperature difference of 500K between 800K and 300K.

Non-equilibrium dynamics, materials and structures for hot carrier solar cells: a detailed review

“…However, if ℏω O -and thus ℏω A -are very small, it immediately follows that f BE ≫ 1 for acoustic phonons and f BE > 1 for optical phonons even at room temperatures which is the basis of thermoelectrics. There, (waste) heat is converted into electricity by such high f BE values of optical phonons (building upon yet higher f BE of their acoustic counterparts) driving the Fermi-Dirac occupation probability f FD of electrons so that these can get extracted at a higher energy above the Fermi level E F [30,31]. With Tellurium (Bismuth) having atomic masses of M Te = 127.6 g mol −1 (M Bi = 209.0 g mol −1 ) [27], it comes as no surprise that Bi 2 Te 3 is a key material in thermoelectrics with ℏω O ≤ 16.5 meV [32], yielding f BE (ℏω O ) ≥ 1.12 at T = 300 K. To this day, there is no refined theoretical treatment of all such processes which determine the energy flux from a HC Fermi-Dirac ensemble obtained by broadband solar irradiation to charge carriers made available at external contacts with energies notably above values known from conventional solar cells.…”

“…Notwithstanding, its Fröhlich IA is almost twice as big as compared to InN; α Fro = 0.43. Alike to InN, the high bond polarity of GaN yields to its most stable form as a würtzite 31 . The large bandgap of GaN excludes it from being a bulk HCA.…”

“…30 The detrimental impact of acoustic modes on quasi-elastic HC transport outweighs the probability of phonon up-conversion to mediate phononic HC energy loss by far, see section 3.2.5. 31 This symmetry occurs by twisting the zb-symmetry into a hexagonal phase where the 3 rd nearest neighbour (3-nn) atom of the lattice site considered is not rotated by 60…”

Amorphous/epitaxial superlattice for thermoelectric application

“…[1][2][3] Lead-salt IV-VI materials such as PbTe, PbS, and PbSe have a small lattice thermal conductivity of 2-3 W m −1 K −1 , and the materials or their alloys have high thermoelectric figures of merit. 8) Although the materials have short mean free paths of phonons compared with Si, 9,10) the introduction of nanostructures is effective even in low-thermal-conductivity materials. [4][5][6][7] In this paper, we propose a new superlattice system consisting of epitaxial and amorphous layers for thermoelectric applications, and discuss the preparation of the structure in a PbGeTeS system.…”