Thermoelectric properties of single-wall carbon nanotube films: Effects of diameter and wet environment

Abstract

The Seebeck coefficient S and the electrical resistivity ρ of single-wall carbon nanotube (SWCNT) films were investigated as a function of the SWCNT diameter and carrier concentration. The S and ρ significantly changed in humid environments through p-type carrier doping. Experiments, combined with theoretical simulations based on the non-equilibrium Green’s function theory, indicated that the power factor P can be increased threefold by the enrichment of semiconducting SWCNTs, but the nanotube diameter has little effect. The improvement of the film resistivity strongly enhances the film thermoelectric performance, manifested as increasing the value of P above 1200 µW/(m·K2).

Interplay Among Thermoelectric Properties, Atmospheric Stability, and Electronic Structures in Solution‐Deposited Thin Films of P(NaX[Niett])

“…(More detailed descriptions are given in Note S5, Supporting Information. )41–50 As depicted in N e ( E ) of Figure 5b, when E F is approaching from 0 to +0.8 eV beyond the unoccupied DOS, | S e | increases through the peak and decreases again due to the trade‐off between the former term and the latter term in Equation ,42–44 which is matched with the regions of I to IV corresponding to annealing temperatures as shown in Figure 5a. The annealing temperature dependence of S and σ and the electronic state obtained in the experiment from Figures 4 and 5a are in good agreement with those shown in Figure 5b.…”

“…Equation shows that competition between two terms leads to the peak in S as a function of E F 42–44. The first term is related to an increased energy dependence of n ( E ), for instance by a local increase in N ( E ), and the second term is related to an increased energy dependence of µ ( E ), for instance by a scattering mechanism that strongly depends on the energy of the charge carriers.…”

Synergistic Impacts of Electrolyte Adsorption on the Thermoelectric Properties of Single‐Walled Carbon Nanotubes

“…In this situation, the Seebeck coefficient must be maximized with the Fermi level at not the top of the valence band but at the inflection point. Water adsorption, although water is volatile, might induce similar p‐doping, leading to an enhancement in thermoelectric properties . Specific interaction between SWNTs and defect structures might additionally contribute to the DOS profile and therefore affect the Seebeck coefficient although they should be rather localized and less effective on the conductivity enhancement.…”

The effect of uniaxial and torsional strains on the Density of States of Single Walled Carbon Nanotubes

“…13 23 h a n n n n c 2,3) in the absence of strain. Next, we use (3-a) and (3-b) to calculate 1 r , 2 r and 3 r in the presence of strain, which are: (8-b) In this step, we can calculate the energy.…”

“…Nonetheless, researches continued to investigate the physical and the electronic properties of carbon nanotubes [2][3][4][5]. It is well known that strain can significantly modify CNT electronic properties, such as band-gap and density of states.…”