Lattice dynamics calculations were performed using the finite-displacement method within the Phonopy package. Convergence of the phonon dispersion with the supercell size used for second-order force constants (FCs) was explicitly checked, as illustrated in Figure . Second-order FCs were computed using a 3×3×1 supercell derived from the 30-atom conventional cell, employing the PBEsol functional. Atom contributions to the lattice dynamics were determined from the atom-projected phonon density of states (PDOS), calculated through Fourier interpolation. The lattice thermal conductivity was calculated using the Phono3py package, which employs a supercell method to calculate the third-order FCs with the PBEsol functional. A 2×2×1 supercell based on the conventional cell was used to calculate the third-order FCs. The lattice thermal conductivity was determined by solving the phonon Boltzmann transport equation within the single-mode relaxation-time approximation. The convergence of qpoint mesh density was verified, and a 13×13×13 mesh was selected, as illustrated in Figure . Plots of the electronic, phonon and thermoelectric properties were generated using Sumo, IFermi and ThermoParser.