Enhanced Thermoelectric Performance of 2D Materials—A Comparative Study of MXene and TMDCs

Advanced materials are vital for high-performance thermoelectric (TE) devices, overcoming the limitations of conventional materials. Two-dimensional (2D) materials like MXenes and transition metal dichalcogenides (TMDCs), such as molybdenum disulfide (MoS₂), show promise due to their unique properties. This study explores the TE potential of pristine monolayer Ti₃C₂ MXene and bulk 2H and monolayer MoS₂ using first-principles density functional theory and a semi-classical Boltzmann transport approach under the constant relaxation time approximation and rigid band approximation [1, 2]. We analyze key transport parameters, including electron thermal and electrical conductivities, Seebeck coefficients, power factor, and figure of merit [2]. Our results reveal distinct electronic structures and superior TE performance for both materials. Ti₃C₂ MXene exhibits unique thermal and electrical transport features, while MoS₂ shows high Seebeck coefficients (up to 1550 μV/K) and ultrahigh power factor values (up to 9.21 × 10¹¹ Wm^-1K^-²s^-1). We demonstrate that the semiconductors are highly efficient in TE power generation, as indicated by their high figure of merit values. However, their low thermal conductivity restricts their effectiveness in TE cooling applications. On the other hand, metals are excellent for cooling due to their high thermal conductivity but are generally inefficient for power generation due to their low Seebeck coefficient and high thermal conductivity. Consequently, semimetals and functionalized MXenes are anticipated to provide a well-balanced performance for both TE power generation and cooling applications. Therefore, our comprehensive analysis provides benchmarks for experimental validation and guidelines for improving TE performance, highlighting the potential of MXenes and TMDCs for advanced energy device applications.<br/><br/><b>References</b><br/>[1] P. Giannozzi, S. Baroni, N. Bonini, M. Calandra, R. Car, C. Cavazzoni, D. Ceresoli, G. L. Chiarotti, M. Cococcioni, I. Dabo, et al., Journal of physics: Condensed matter<b> 21</b>, 395502 (2009).<br/>[2] G. K. Madsen, J. Carrete, and M. J. Verstraete, Computer Physics Communications 231, 140 (2018).<br/><br/><b>Acknowledgments</b><br/>The authors acknowledge the financial support from the Science and Engineering Research Board (SERB), Government of India, under Grant No. CRG/2021/003102.