Computational Exploration of Ultralow Lattice Thermal Conductivity and High Figure of Merit in p-Type Bulk RbX₂Sb (X = K, Na)

Abstract

Using density functional theory and the Boltzmann transport equation, we have herein studied the electronic structure and thermoelectric behavior of two bulk bialkali antimonides RbK2Sb and RbNa2Sb. Our calculation reveals that both the antimonides exhibit ultralow lattice thermal conductivities resulting from the intrinsic phonon scattering. The lattice thermal conductivities of RbK2Sb and RbNa2Sb at 700 K (300 K) are found to be 0.150 (0.350) and 0.228 (0.532) W m–1 K–1, respectively. Thermodynamically, mechanically, dynamically, and thermally stable p-type RbK2Sb proclaims high values of the Seebeck coefficient due to the large band effective masses and thus the DOS effective masses of the holes, while p-type RbNa2Sb exhibits a moderate Seebeck coefficient and optimum electrical conductivity due to the relatively lower band effective mass and the high relaxation time (corresponding to high mobility) of the holes. Estimated maximum values of the figure of merit at 700 K (300 K) are 4.40 (1.91) and 5.84 (2.76) for the p-type RbK2Sb and RbNa2Sb, respectively.

PtTe2/Sb2S3 Nanoscale Heterostructures for the Photocatalytic Direct Z-Scheme with High Solar-to-Hydrogen Efficiency: A Theoretical Investigation

“…Here, the three lowest vibration frequency modes are the out-of-plane acoustic mode (ZA), the in-plane transversal acoustic mode (TA), and the in-plane longitudinal acoustic mode (LA), while the other branches are optical modes. The absence of any negative phonon frequency in the dispersion curves confirms the dynamical stability of both two monolayers . Three acoustic and six optical phonon branches can be observed for the PtTe 2 monolayer (Figure a), while three acoustic and twelve optical phonon branches are found for the Sb 2 S 3 monolayer (Figure b) due to the different numbers of vibrational free degrees.…”

“…The absence of any negative phonon frequency in the dispersion curves confirms the dynamical stability of both two monolayers. 38 Three acoustic and six optical phonon branches can be observed for the PtTe 2 monolayer (Figure 2a), while three acoustic and twelve optical phonon branches are found for the Sb 2 S 3 monolayer (Figure 2b) due to the different numbers of vibrational free degrees.…”

Point defect-mediated hot carrier relaxation dynamics of lead-free FASnI3 perovskites

“…Numerous investigations have been made on MHPs, which exhibit a variety of beneficial and distinctive characteristics, including lengthy electron and hole diffusion, high charge carrier mobility, strong optical absorption, and a band gap tuning over a broad energy range. [2][3][4][5][6] MHPs have gained a lot of interest for optoelectronic device applications, including solar cells, light-emitting diodes, photodetectors, sensors, secondary storage systems, etc. due to their exceptional photoelectric capabilities and low production costs.…”

Physical insights into the ultralow lattice thermal conductivity and high thermoelectric performance of bulk LiMTe2 (M = Al, Ga)

“…The anharmonicity of a periodic crystal can be partially characterized by another useful parameter, the Grüneisen parameter, 55–57 as shown in the right panel of Fig. 1(c) and (f).…”

“…The anharmonicity of a periodic crystal can be partially characterized by another useful parameter, the Gru ¨neisen parameter, [55][56][57] as shown in the right panel of Fig. 1(c We obtained average Gru ¨neisen parameter ( g) (calculated considering the major heat-carrying phonon modes: 12 acoustic and low-frequency optical modes) values of 0.53 and 1.62 for LiAlTe 2 and LiGaTe 2 , respectively, which are comparable to or higher than those of many highly anharmonic crystals, such as 1.57 for the In 2 STe 2 monolayer, 51 1.58 for Sb 2 Se 3 , 58 1.50 for BiCuSeO, 59 1.45 for PbTe, 60 1.37 for Tm oh Ag oh Te 2 , 61 1.13 for CuTaS 3 , 62 etc.…”