Improved thermoelectric figure of merit in polyol method prepared (Cu7Te4)1−x(MnTe2)x (x ≤ 0.06) nanocomposites

Impact of Copper Intercalation on Thermoelectric Properties in Polyol Method-Prepared CuxBi2Se3, x = 0, 0.05, 0.10, and 0.15 Nanosheets

“…The nearly linear dependence of S on temperature suggests diffusive transport under applied thermal gradients as the dominant transport mechanism. 6 The magnitude of |S| at 300 K ranges from ∼82.77 to 97 μV K −1 and decreases with Cu doping.…”

“…Here, the spin−orbit splitting of Bi 4f 7/2 and 4f 5/2 for both samples is 5.4 eV, which is near that of pure bulk Bi 4f. 36 Therefore, Bi retained its Bi 3+ oxidation state after the introduction of Cu in the Bi 2 Se 3 lattice. The peaks at 162.05 and 162.36 eV observed on fitting the spectra corresponds to the Se 3p orbital.…”

“…37 High-resolution spectra of Cu have two peaks at 951.32 eV and 931.22 eV for 2p 1/2 and 2p 3/2 , respectively, corresponding to Cu + states (Figure 3f) that match the earlier report. 6 A very weak satellite peak of copper can be observed at 940.58 eV. 6,38 This implies that very few copper are in the Cu 2+ state, which may substitute Bi 3+ in the host lattice.…”

“…6 A very weak satellite peak of copper can be observed at 940.58 eV. 6,38 This implies that very few copper are in the Cu 2+ state, which may substitute Bi 3+ in the host lattice. It can be seen that the binding energies of Bi 4f and Se 3d are slightly shifted to higher energies with the introduction of copper in Bi 2 Se 3 , suggesting that Se and Bi atoms move toward Cu atoms, leading to increased electron doping in the vdW gap due to Cu intercalation.…”

“…A good approach for increasing ZT is to increase the power factor (PF = S 2 σ) and decrease κ l . PF can be enhanced by increasing the rate of change of density of states (DOS) at the Fermi level (E F ), 1 low energy charge career filtering through the introduction of point defects, 3,6,7 nanostructuring, 5 and choosing highly anisotropic layered materials with heavy elements in a large unit cell. 7 Nanostructuring can be achieved through two methods: decreasing the size of grains or incorporating nanomaterials as impurities in bulk or nanohost materials.…”