Research Article Thermoelectric Transport Properties of Cu Nanoprecipitates Embedded Bi 2 Te 2.7 Se 0.3 Eunsil Lee, 1 Jin Il Kim, 1 Soon-Mok Choi, 2 Young Soo Lim, 3 Won-Seon Seo, 3 Jong-Young Kim, 1 and Kyu Hyoung Lee 4 1 Korea Institute of Ceramic Engineering and Technology, Icheon Branch, Icheon 467-843, Republic of Korea 2 School of Energy, Materials and Chemical Engineering, Korea University of Technology and Education, Cheonan 330-708, Republic of Korea 3 Energy and Environmental Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801, Republic of Korea 4 Department of Nano Applied Engineering, Kangwon National University, Chuncheon 200-701, Republic of Korea Correspondence should be addressed to Jong-Young Kim; jykim@kicet.re.kr and Kyu Hyoung Lee; khlee2014@kangwon.ac.kr Received 20 October 2014; Revised 14 February 2015; Accepted 7 March 2015 Academic Editor: Doron Yadlovker Copyright © 2015 Eunsil Lee et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We suggest a simple and scalable synthesis to prepare Cu-Bi 2 Te 2.7 Se 0.3 (Cu-BTS) nanocomposites. By precipitating Cu nanoparticle (NP) in colloidal suspension of as-exfoliated BTS, homogeneous mixtures of Cu NP and BTS nanosheet were readily achieved, and then the sintered nanocomposites were fabricated by spark plasma sintering technique using the mixed powder as a raw material. Te precipitated Cu NPs in the BTS matrix efectively generated nanograin (BTS) and heterointerface (Cu/BTS) structures. Te maximum  of 0.90 at 400 K, which is 15% higher compared to that of pristine BTS, was obtained in 3 vol% Cu-BTS nanocomposite. Te enhancement of  resulted from improved power factor by carrier fltering efect due to the Cu nanoprecipitates in the BTS matrix. 1. Introduction Termoelectric (TE) power generation is a key technology for clean renewable energy harvesting and reduction of green- house gas. Widespread use of TE power generation systems requires enhancement in performance of TE materials, eval- uated in terms of a dimensionless fgure merit, defned as  =  ⋅  2 ⋅ /, where  is the electrical conductivity,  is the Seebeck coefcient, and  is the total thermal conductivity at a given absolute temperature (). Among TE materials, the Bi 2 Te 3 -based solid solution, such as p-type Bi 2−x Sb x Te 3 (BST) and n-type Bi 2 Te 3−y Se y (BTS), is known to be the best material among those used around room temperature. Although Bi 2 Te 3 -based TE materials are widely used for small-scale and high-density cooling applications, materials with higher  are required for the extension of application, including domestic cooling and power generation from low- grade heat. Recently, high-performance p-type Bi 2 Te 3 -based bulk TE materials have been developed with the introduction of nanotechnology, which reduce the lattice thermal conduc- tivity ( lat =− ele , where  ele is the electronic contribution) by intensifed interface phonon scattering. Poudel et al. reported a signifcant improvement of  that resulted from a reduced grain size [1]. High  of 1.4 was obtained at 373 K owing to the reduced  lat . Te key feature of the  lat reduction in this nanograined composite is the high density of the grain boundaries to scatter phonons [1, 2]. However, for the nanostructured n-type BTS, the  value still remains about 1.04 at 398 K even in nanograined composite [3]. Moreover, the carrier concentration () increased by formation of point defects (antisite defects and vacancies) generated by heavy deformation during ball milling (BM) process [4]. Tis uncontrollable defect in BTS is known to bring about severe reproducibility issue; thus there have been a lot of eforts to simultaneously enhance the  and improve the reproducibility through the composite-type materials with metallic dispersions such as Cu, In, and Cu-Te [5–8]. Hindawi Publishing Corporation Journal of Nanomaterials Volume 2015, Article ID 820893, 5 pages http://dx.doi.org/10.1155/2015/820893