热电材料外文翻译

Thermoelectric Properties of n -Type Bi 2Te 3/PbSe 0.5Te 0.5Segmented Thermoelectric Material

SEJIN YOON,1JUN-YOUNG CHO,1HYUN KOO,1SUNG-HWAN BAE,1SEUNGHYUN AHN,1GWI RANG KIM,1JIN-SANG KIM,2and CHAN PARK 1,3,4

1.—Department of Materials Science and Engineering,Seoul National University,Daehak-dong,Gwanak-gu,Seoul,Republic of Korea.

2.—Electronic Materials Research Center,Korea Institute of Science and Technology,Wolgok 2-dong,Seongbuk-gu,Seoul,Republic of Korea.

3.—Research Institute of Advanced Materials,Seoul National University,Daehak-dong,Gwanak-gu,Seoul,Republic of Korea.

4.—e-mail:pchan@snu.ac.kr

To investigate the effects of segmentation of thermoelectric materials on performance levels,n -type segmented Bi 2Te 3/PbSe 0.5Te 0.5thermoelectric material was fabricated,and its output power was measured and compared with those of Bi 2Te 3and PbSe 0.5Te 0.5.The two materials were bonded by diffusion bonding with a diffusion layer that was $18l m thick.The electrical conductivity,Seebeck coefficient,and power factor of the segmented Bi 2Te 3/PbSe 0.5Te 0.5sample were close to the average of the values for Bi 2Te 3and PbSe 0.5Te 0.5.The output power of Bi 2Te 3was higher than those of PbSe 0.5Te 0.5and the segmented sample for small D T (300K to 400K and 300K to 500K),but that of the segmented sample was higher than those of Bi 2Te 3and PbSe 0.5Te 0.5when D T exceeded 300K (300K to 600K and 300K to 700K).The output power of the segmented sample was about 15%and 73%higher than those of the Bi 2Te 3and PbSe 0.5Te 0.5samples,respectively,when D T was 400K (300K to 700K).The efficiency of thermoelectric materials for large temperature differences can be enhanced by segmenting materials with high performance in different temperature ranges.

Key words:Thermoelectric material,segmented thermoelectric material,

Bi 2Te 3,Pb(Se,Te),output power

INTRODUCTION

Many studies have focused on improving the energy conversion efficiency of thermoelectric materials for their potential use in power-generation and cooling systems.The efficiency of a thermoelectric material is characterized by its dimensionless figure of merit [zT =(S 2r T )/j ,where S is the Seebeck coefficient,r is the electrical conductivity,and j denotes the thermal

conductivity].1

The upper limit of the efficiency (g ¼g c ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

1þzT p À1 =ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi1þzT p þ1Àg c h i ,where

g c =D T /T hot is the Carnot efficiency,and zT is the average zT over the temperature range)is determined by the temperature difference D T ,2,3which means that better energy conversion can be expected with the use of a larger D T .Most thermoelectric materials,how-ever,have high zT over a very limited temperature range,indicating that most thermoelectric materials cannot effectively utilize such a large D T .High ther-moelectric energy conversion efficiency can be obtained when a large D T can be used,which can only be realized by using a thermoelectric material with high zT value across a broad temperature range.Materials with large average zT values over a wide temperature range have to be used to convert large amounts of energy from a large D T .Connection of materials with high zT values in different tempera-ture ranges,forming a segmented thermoelectric

(Received May 10,2013;accepted October 14,2013;published online November 27,2013)

Journal of ELECTRONIC MATERIALS,Vol.43,No.2,2014

DOI:10.1007/s11664-013-2869-4Ó2013TMS

414