Modification of electronic structure and thermoelectric properties of hole-doped tungsten dichalcogenides

Abstract

We present a study on the modification of the electronic structure and hole-doping effect for the layered dichalcogenide WSe2 with a multi-valley band structure, where Ta is doped on the W site along with a partial substitution of Te for its lighter counterpart Se. By means of bandstructure calculations and specific-heat measurements, the introduction of Te is theoretically and experimentally found to change the electronic states in WSe2. While in WSe2 the valence-band maximum is located at the Γ point, the introduction of Te raises the bands at the K point with respect to the Γ point. In addition, thermal-transport measurements reveal a smaller thermal conductivity at room temperature of W1−xTaxSe1.6Te0.4 than reported for W1−xTaxSe2. However, when approaching 900 K, the thermal conductivities of both systems converge while the resistivity in W1−xTaxSe1.6Te0.4 is larger than in W1−xTaxSe2, leading to comparable but slightly smaller values of the figure of merit in W1−xTaxSe1.6Te0.4.

Endeavor of Iontronics: From Fundamentals to Applications of Ion‐Controlled Electronics

“…On the other hand, EDL gating continuously controls the carrier density without introducing defects and crystal disorder. One such example is WSe 2 , which is known as a good thermoelectric material and has been investigated by using doped bulk polycrystals . The n dependence of σ and S is shown in Figure c,d .…”

“…For comparison, the experimental data for bulk WSe 2 crystals are also plotted as green colored symbols in Figure a–c . Here, there are several important features to be noticed.…”

Charge Transfer and Functionalization of Monolayer InSe by Physisorption of Small Molecules for Gas Sensing

“…As a result, 2D materials are highly suitable for gas sensing via modulating the carrier density and shifting the Fermi level 12,13 . Last but not least, 2D materials can be easily functionalized by molecular doping, which can be used to modify their electronic, optical, and thermoelectric properties [17][18][19][20][21][22][23] , in addition to strain engineering and heterogeneous construction 24,25 .…”

Prediction for electronic, vibrational and thermoelectric properties of chalcopyrite AgX(X=In,Ga)Te 2 : PBE + U approach

“…The ZT value can be improved by increasing the power factor (PF = S 2 σ ) or decreasing thermal conductivity. The PF can be improved by using 'band engineering' to increase the effective mass and carrier concentration optimization [2][3][4][5][6]. The lattice thermal conductivity can be decreased by using some strategies to increase the scattering of phonon waves such as the introduction of lattice imperfection [7] or nanoscale and mesoscale crystal structures [8][9][10][11][12].…”