Interfacial energy band and phonon scattering effect in Bi2Te3-polypyrrole hybrid thermoelectric material

Abstract

Enhanced thermoelectric efficiency in topological insulator Bi 2 Te 3 nanoplates via atomic layer deposition-based surface passivation Applied Physics Letters 113, 083904 (2018);

Exceptionally High Power Factor Ag2Se/Se/Polypyrrole Composite Films for Flexible Thermoelectric Generators

“…The σ of the AP1 is 1064 S cm −1 at 300 K, and it shows an upward trend as the temperature increases up to 390 K. The S decreases gradually from 144 µV K −1 at RT to 138 µV K −1 at 390 K. Both the σ and S have a sharp drop when T increases from 390 to 410 K, which is attributed to the phase transition of Ag 2 Se around 407 K. [29] Consequently, the PF shows a value of 2240 µW m −1 K −2 at RT and reaches a maximum value of 2670 µW m −1 K −2 at 390 K. The PF at RT is comparable to that of the inflexible Ag 2 Se film [26] and that of the Bi 2 Te 3 /PPy bulk material. [38] All the PF values are above 2200 µW m −1 K −2 when the temperature is in the range of 300-390 K, suggesting that the composite film has great potential for practical applications.…”

“…This is because there might exist an energy filtering effect at the Ag 2 Se/PPy interface. [14,38] The energy band of the Ag 2 Se film was investigated by ultraviolet photoelectron spectroscopy and UV-vis-NIR diffuse reflectance spectroscopy to obtain work function (Φ) and bandgap (E g ), respectively. He I (hν = 21.2 eV) was used as the energy source.…”

“…Considering that a small amount of Py was added, the polymerization degree of the PPy in the composite film is not easy to be determined, the Φ, E g , and χ of 4.58, 2.85, and 3.05 eV, respectively, for PPy, are referred to ref. [38]. Thus, the complete band diagram for Ag 2 Se and PPy is shown in Figure S11a (Supporting Information), and the equilibrium band diagram is given in Figure S11b (Supporting Information).…”

“…Hence, PPy has recently attracted more attention. [35][36][37][38] For example, a Bi 2 Te 3 /PPy bulk TE composite was prepared by spark plasma sintering at 350 °C and 100 MPa for 2 min in Ar. [38] The composite not only shows a high PF (≈2200 µW m −1 K −2 at RT) comparable to that of the pristine Bi 2 Te 3 , but also has a lower thermal conductivity; hence its ZT value reaches 0.98 at RT.…”

Enhancing the Seebeck effect in Ge/Si through the combination of interfacial design features

“…This insight was improved considerably by fabricating textured polycrystals of superlattice phases, which generate appropriate potential barriers that can manipulate the phonon and electron transport 16 . Furthermore, as shown by Kim et al ., the inclusion of the conducting polymer, polypyrrole, in the Bi 2 Te 3 matrix enhances the phonon scattering at the interface of the two components in this hybrid material and thus makes the Seebeck coefficient considerably greater than one achieved in pristine Bi 2 Te 3 17 . As noted by Tureson et al ., the presence of Mg implanted ions in epitaxial ScN films introduces an interesting approach to enhance the Seebeck coefficient 18 .…”