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A1: Low temperature materials
Due to the world’s demand for energy and the environmental impact of global climate change caused by the combustion of fossil fuels, thermoelectric (TE) materials, which allow direct conversion between thermal energy and electricity without pollution, have received considerable attention recently as a green option for various energy-harvesting applications ranging from power generation to microprocessor cooling [1]. Compared to traditional inorganic semiconductors, conducting polymers are considered as intriguing alternatives for TE due to their unique advantages, such as inherently low thermal conductivity, high electron/hole mobility, potential low costs owing to abundance of carbon resources, facile processing into versatile forms, possible separate and recovery concerning to environmental burden [2,3]. Up to date, several conducting polymers, including polyacetylene, polyaniline, polythiophene, polypyrrole, and some of their derivatives, have been investigated for use in thermoelectrics [3,4]. Among them, polythiophenes are the most studied conducting polymers as TE materials. However, despite many papers published on polythiophene and its derivatives, very little is known about the TE properties of its close analog, PSE and its derivatives. Most recently, our group investigated the thermoelectric performances of different types of polyselenophene (PSE) prepared by different methods/conditions and found that PSE exhibits very high Seebeck coefficient (>180 V K-1) despite its relatively low electrical conductivity (10-5 to 10-2 S cm-1) [5]. Based on our previous results, we herein investigated systematically the thermoelectric performances of electrosynthesized polyselenophene from different selenophene precursors, namely, from selenophene, biselenophene, and triselenophene. Contrary to oligothiophenes, the longer oligomer chain length lead to improved electrical conductivity and better redox properties, and also improved thermoelectric performances.
References:
[1] L.E. Bell, Science 321 (2008) 1457–1461.
[2] M. Leclerc, A. Najari, Nature Mater. 10 (2011) 409–410.
[3] N. Dubey, M. Leclerc, J. Polym. Sci. Part B: Polym. Phys. 49 (2011) 467–475.
[4] R.R. Yue, J.K. Xu, Synthetic Met. 162 (2012) 912–917.
[5] B.Y. Lu, S. Chen, J.K. Xu, G.Q. Zhao, Synthetic Met. 183 (2013) 8–15.