High Thermoelectric Performance in Cu-Doped Bi₂Te_2.7Se_0.33 Due to Cl Doping and Multiscale AgBiSe₂

Abstract

The thermoelectric performance of n-type Bi2Te3 needs further enhancement to match that of its p-type Bi2Te3 counterpart and should be considered for competitive applications. Combining Cu/Cl and multiscale additives (AgBiSe2) presents a suitable route for such enhancement. This is evidence of the enhanced thermoelectric performance of Bi1.995Cu0.005Te2.69Se0.33Cl0.03. Moreover, by incorporating 0.65 wt % AgBiSe2 (ABS) into Bi1.995Cu0.005Te2.69Se0.33Cl0.03, we further reduce its lattice thermal conductivity to ∼0.28 W m–1 K–1 at 353 K owing to the extra phonon scattering of multiscale ABS. Additionally, the Seebeck coefficient enhances (−183.89 μV K–1 at 353 K) owing to the matrix’s reduced carrier concentration caused by ABS. As a result, we achieve a high ZT of ∼1.25 (at 353 K) and a high ZT ave of ∼1.12 at 300–433 K for Bi1.995Cu0.005Te2.69Se0.33Cl0.03 + 0.65 wt % ABS. This work provides a promising strategy for enhancing the thermoelectric performance of n-type Bi2Te3 through Cu/Cl doping and ABS incorporation.

Suppression of bipolar excitation and enhanced thermoelectric performance in n-type Bi2Te3 with argyrodite Ag8SnSe6 inclusion

“…Moreover, the sample 0.25 wt% STSe shows the minimum κ lat of 0.28 W m −1 K −1 at 353 K. This value is among the lowest in n-type Bi 2 Te 3 research 36–40 and is made possible by the presence of extrinsic nanoscale lattice imperfections such as Ag Bi and Sn Bi defects, dislocations, and Moiré fringes. These imperfections impede phonon transport.…”

“…To analyze their electrical and thermal properties, the samples were cut into specific dimensions (4.5 mm × 4.5 mm × 13 mm and 10 mm × 10 mm × 1.3 mm block specimens) using a low-speed diamond saw (SYJ-160). Given the anisotropic nature of Bi 2 Te 3 -based alloys, 34–41 maintaining the sample orientation was crucial. The S and resistivity ( ρ ) were measured concurrently in a chamber under 1 × 10 −1 Pa using a Namicro-III thermoelectric measurement device, achieving 5% and 5% accuracy, respectively.…”

“…31–33 On the other hand, nanostructured polycrystalline n-type Bi 2 Te 3 materials have been continuously investigated in depth, mainly due to their enhanced properties. 34–40…”

“…The inclusion of secondary phases with semiconductors is an effective strategy to improve the Seebeck coefficient ( S ) while maintaining high σ, and multidimensional nano/microscale crystal or lattice imperfections are effective in suppressing κ lat due to strengthened phonon scattering at these sources. For example, semiconductor thermoelectrics such as GaAs, 34 AgBiSe, 35,36 SnS 2 , 37 Ag 2 Te, 38 Bi 2 S 3 , 39 and InSb 40 have been used in n-type Bi 2 Te 3 and have significantly improved performance. 33–41 For instance, the use of Bi 2 S 3 in Bi 2 Te 2.7 Se 0.3 has resulted in a ZT peak value of 1.2 at 473 K for the composition Bi 2 Te 2.7 Se 0.3 + 1 wt% Bi 2 S 3 due to increased σ and a low κ lat of 0.244 W m −1 K −1 .…”

“…For example, semiconductor thermoelectrics such as GaAs, 34 AgBiSe, 35,36 SnS 2 , 37 Ag 2 Te, 38 Bi 2 S 3 , 39 and InSb 40 have been used in n-type Bi 2 Te 3 and have significantly improved performance. 33–41 For instance, the use of Bi 2 S 3 in Bi 2 Te 2.7 Se 0.3 has resulted in a ZT peak value of 1.2 at 473 K for the composition Bi 2 Te 2.7 Se 0.3 + 1 wt% Bi 2 S 3 due to increased σ and a low κ lat of 0.244 W m −1 K −1 . 39…”