Abstract :

Tellurium free thermoelectric materials and devices for energy harvesting  applications

J. Archana1*
1*Centre of Excellence in Materials and Advanced Technologies (CeMAT), Faculty of
Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur-603
203, India

E-mail: archanaj@srmist.edu.in

Thermoelectric (TE) technology has been evolving rapidly to satisfy the growing
demand for sustainable energy, which can directly convert thermal energy into electricity and
vice versa, offering numerous prospects and potential benefits in energy conversion
technologies. Since tellurium (Te)-based compounds have exhibited high TE efficiency and
have become the dominant in TE technologies. It has several disadvantages, such as high cost,
being rare in the Earth’s crust, and being toxic in nature. In search of Te-free materials for TE
applications, the following compounds such as Bi2Se3, Mg3Sb2, and MnSi exhibit the
promising TE performance in the near room temperature to intermediate temperature region.
Our research focuses on the decoupling of interrelated carrier and thermal transport properties
through strategies such as point defect scattering, lattice strain, dislocations, and grain
boundaries for high TE performance. The p-type Ga and Mn co-doped Bi2Se3 exhibits a low
lattice thermal conductivity of 0.5 W/mK due to point defect scattering and dominance of holes
enhances the power factor, leading to a high zT of 0.25 at 303 K.

Further, the Ga and Ge codoped Bi2Se3 reached an improved power factor of 1403 μW/mK2 and ultra-low ԟL of 0.24
W/mK via band flattening and strain field, which significantly maximized the zT of 0.7 at 513
K. The exploration of the Nowotny chimney-ladder crystal structure of higher manganese
silicide (HMS) exhibits promising results with a hybrid composite of a carbon nanofiber
(CNF), thus leading to an interfacial energy filtering effect. This maximizes the power factor
of 1755.63 μW/mK2 at 803 K, while the ԟL is as low as 1.95 W/mK, and attains a peak zT value
of 0.64 at 803 K. The incorporation of Zn into Mg3Sb2 significantly reduces the ԟL of 0.46
W/mK via the mass and strain field fluctuations in the lattice, resulting in an enhanced
thermoelectric figure of merit of 0.25 at 753 K. Recently, the heavy element Ag substitution
in p-type Mg1.8Zn1.2Sb2 solid-solution notably lowers the lattice thermal conductivity of 0.56
W/mK at 753 K and maximizes the power factor of 456 μW/mK2 via band convergence and
defect engineering, which greatly improved the zT of 0.5. The results obtained demonstrated
the potential possibilities to fabricate the thermoelectric generator for room to mid-temperature
energy harvesting applications.

References:
1. J. Archana, et al. Applied Physics Letters 125, no. 17 (2024).
2 J. Archana, et al. Applied Physics Letters 124, no. 3 (2024).
3. J. Archana, et al. Chemical Communications, (2023).
4. J. Archana, et al. Energy Mater. (2025) In Press.
5. J. Archana, et al. Small 21, no. 6 (2025): 2410622