Synthesis of Bis-Terpyridine-Based Metallopolymers and the Thermoelectric Properties of Their Single Walled Carbon Nanotube Composites.

Jiahua Li,Wai-Yeung Wong,Zeling Guo,Linli Xu

doi:10.3390/molecules26092560

Abstract

Although the organic and the conventional inorganic thermoelectric (TE) materials have been extensively developed in recent years, the number of cases involving conducting metallopolymers is still quite limited. In view of the versatile coordination capability of the terpyridine fraction and the electron-rich nature of the 3,4-ethylenedioxythiophene moiety, a bis-terpyridine-featured ligand was designed, and a series of metallopolymers were then synthesized. Upon the addition of single-walled carbon nanotube (SWCNT), the TE properties of the resulting metallopolymer-SWCNT composite films were investigated. It was found that metal centres played an important role in affecting the morphology of the thin films, which was a key factor that determined the TE performances of the composites. Additionally, the energy levels of the metallopolymers were feasibly tuned by selecting different metal centres. With the combined effects of a uniform and condensed surface and an optimized band structure, the highest power factor was achieved by the Cu(II)-containing metallopolymer-SWCNT composite at the doping ratio of 75%, which reached 38.3 μW·m−1·K−2.

Highlights

As a green approach to convert heat into electrical energy, thermoelectric (TE) materials are showing their promising prospect in both macro-scaled and mini-scaled applications, such as power generation, health monitors, etc. [1,2], and have received tremendous attention
The TE performance of a material is assessed by its figure-of-merit (ZT): ZT = S2σT/κ, where S is the Seebeck coefficient (V·K−1), σ is the electrical conductivity (S·m−1), T is the absolute temperature (K), and κ is the thermal conductivity (W·m−1·K−1) [2,3]
The nuclear magnetic resonance (NMR) spectra were acquired on a Varian VNMRS 400 spectrometer or a Bruker AVANCE III 400 spectrometer. 1H NMR spectra were quoted relative to the internal reference tetramethylsilane (TMS, δ = 0.00 ppm)

Summary

Introduction

As a green approach to convert heat into electrical energy, thermoelectric (TE) materials are showing their promising prospect in both macro-scaled and mini-scaled applications, such as power generation, health monitors, etc. [1,2], and have received tremendous attention. The involvement of appropriate transition metal ions could increase the probability to provide active species during the electrical conducting process [19,20,21], tune the energy levels through d-π conjugation feasibly [19,22], generate various molecular geometries according to the coordinating properties of the metal centres and lower the thermal conductivity [9] In this regard, Zhu et al successfully developed a series of 1,1,2,2-ethenetetrathiolatebased metallopolymers [poly(M(ett)] with tunable TE performances when different metal centres or processing methods were adopted [23,24,25].

22.1..MMaatteerirailasls and Methods

Characterization

Chemical Structure Determination