Study of the Lattice Thermal Conductivity of Janus In 2 Ge 2 S 6 and In 2 Ge 2 S 3 Se 3 Bilayers

AbstractIn this paper, we investigate the lattice thermal conductivity of Janus In2Ge2S6 and In2Ge2S3Se3 bilayers by solving the phonon Boltzmann transport equation using first-principles calculations. We found that this is mainly due to the fact that the frequencies at which larger gaps appear in the intermediate and high frequency optical branches of In2Ge2S3Se3 are smaller than those of In2Ge2S6, which shifts the phonon dispersion curve of In2Ge2S3Se3 downward, which makes the overall phonon group velocity of In2Ge2S3Se3 material smaller than that of In2Ge2Se6 material, and also due to the fact that In2Ge2S3Se3 soft bending in the finite layer thickness coupling and the tight connection of the in-plane acoustic modes, resulting in increased phonon-phonon scattering processes, shorter phonon relaxation times, and larger Grüneisen parameters indicating a stronger anharmonic In2Ge2S3Se3 structure, all these factors combined lead to a lattice thermal conductivity of In2Ge2S3Se3 smaller than the lattice thermal conductivity of In2Ge2S6. At a temperature of 1000 K, the In2Ge2S3Se3 structure has a minimum lattice thermal conductivity of about 0.22 W/mK, and In2Ge2S6 has a minimum lattice thermal conductivity of about 0.4 W/mK. Our results suggest that Janus In2Ge2S6 and In2Ge2S3Se3 bilayers are potential for future thermal management of nanoelectronic devices and thermoelectric devices. two-dimensional materials.Keywords: Two-dimensional materialsFirst-principles calculationsLattice thermal conductivity Disclosure StatementNo potential conflict of interest was reported by the author(s).