Abstract
Bi2Te3–CNT–PEDOT nanocomposites have been synthesized by mixing PEDOT:PSS with hydrothermally synthesized Bi2Te3–CNT nanocomposites. Introducing conducting interfaces by adding PEDOT in Bi2Te3–CNT boosts the charge carrier mobility, resulting in improved electrical conductivity and simultaneously lowering the lattice thermal conductivity by enhancing phonon scattering and thus resulting in two-fold enhancement of the figure of merit. The detailed mechanism behind the enhancement of charge carrier mobility is discussed by considering the role of conducting interfaces and strong coupling of CNTs and PEDOT conducting chains. The formation of a large number of interfaces in Bi2Te3–CNT–PEDOT nanocomposites acts as strong scattering centers and thermal barriers for long-wavelength phonons, which reduces the lattice thermal conductivity. The formation of interfaces between Bi2Te3 nanostructures and CNT–PEDOT conducting channels has been studied by Kelvin probe force microscopy which clearly showed a smaller interface potential barrier for the Bi2Te3–CNT–PEDOT nanocomposite.
Highlights
In this work, sulfonated confirms the presence of secondary phase (CNTs) and PEDOT:PSS were used for the synthesis of the Bi2Te3–CNT–PEDOT nanocomposite which exhibits a much enhanced thermoelectric power factor and a higher figure of merit
The Kelvin probe force microscopy has been carried out to study the interface between Bi2Te3 nanostructures and CNT–PEDOT conducting channels
The Bi2Te3–CNT was synthesized by the hydrothermal technique in which 1% sulfonated CNT was added in the precursor for the synthesis of Bi2Te3
Summary
Thermoelectric conversion has drawn great attention toward the generation of electricity from abundant waste heat resources.1 In order to achieve higher performance of a thermoelectric material, the Seebeck coefficient (S) and electrical conductivity (σ) should be large and thermal conductivity (κ) should be small.2 due to interdependence of S, σ, and κ, it is challenging to control them independently.3 it is essential to decouple S, σ, and κ for achieving higher performance of a thermoelectric material.4 By increasing carrier mobility rather than carrier concentration, S and σ can be decoupled.5 The reduction in lattice thermal conductivity has been achieved through nanostructuring of various thermoelectric materials.6 Recently, reduction in lattice thermal conductivity is achieved by introducing more conducting interfaces through nanocomposite engineering without less affecting the Seebeck coefficient and electrical conductivity.7 Bismuth telluride and its nanocomposites are efficient thermoelectric materials near room temperature and have attracted great attention for room temperature applications.8 Recently, lots of efforts have been made for the thermoelectric study of various Bi2Te3 nanostructures and nanocomposites to improve the figure of merit.9,10 An enhanced figure of merit in Bi2Te3–P3HT, Cu–Bi2Te3, Bi2Te3–PEDOT:PSS, Te– Bi2Te3–PEDOT:PSS, Bi2Te3–PANI, Bi2Te3–graphene, and MoS2– Bi2Te3,Bi2Te2.4Se0.6–CNT nanocomposites has been reported.11–17 Nanocomposites of conducting polymer/inorganic thermoelectric materials have attracted attention for enhancing thermoelectric properties.18–20 there is no report published on the thermoelectric properties of the Bi2Te3 ternary nanocomposite through the formation of interfaces to achieve an increased thermoelectric power factor and smaller thermal conductivity simultaneously. The increase in the electrical conductivity of Bi2Te3 is observed after the incorporation of CNTs and PEDOT:PSS [Fig. 2(a)].
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