Thermoelectric (TE) materials, which are capable of direct energy conversions between heat and electricity, are of great importance in the energy field because of the following advantages over traditional methods in refrigeration and power generation. To attain good TE performances, a high figure of merit (ZT) value is preferred, which implies that a large thermopower (the absolute value of Seebeck coefficient (S)), a high electrical conductivity, and a low thermal conductivity are all expected. However, the optimization of ZT represents a grand challenge in material sciences because these three comprising parameters are conflictingly correlated and cannot be tuned independently. As a result of continuing efforts for decades, various innovative approaches and concepts have been developed to enhance TE performance, such as alloying, nano-engineering, band convergence, energy filtering, hierarchical architecturing, chemical doping and functionalization, strain engineering, defect engineering, and making heterostructures. Nanostructuring is the most widely used approach for acquiring a low thermal conductivity and, thereby, a high ZT. Nanostructures can suppress the thermal conductivity by interface or boundary scattering of phonons and can enhance the power factor by the quantum confinement of electrons. We proposed a non-contact measurement technique to calculate the lattice thermal conductivity (L) from the temperature and power-dependent Raman spectra of the Bi2Se3 nanocrystals. The preparation of Bi2Se3 nanocrystals using the hot injection of non-toxic solvent and the calculation for the L from the Raman Spectroscopy of Bi2Se3 will be discussed by considering the Bond-Order-Length-Strength [1] and Local Bond Averaging [2]. The simulation of the L of the Bi2Se3 using the Phono3py under quasi-harmonic approximation will also be present and compared with the experimental value.[3]

References

[1] J. W. Li, L. W. Yang, Z. F. Zhou, X. J. Liu, G. F. Xie, Y. Pan, and C. Q. Sun The Journal of Physical Chemistry B 2010 114 (4), 1648-1651 DOI: 10.1021/jp909952c

[2] C. Q. Sun, Prog. Mater. Sci. 2009 54, 179 DOI: 10.1016/j.pmatsci.2008.08.001

[3] K. E. Vipin, S. K. Das, and P. Padhan Phys. Chem. Chem. Phys., 2023 25(19), 13577-13586. DOI : 10.1039/D3CP00515A