Thermoelectric materials and devices can provide a promising possibility to easily convert energy between heat and electricity without moving parts and environmentally benign.And thermoelectric energy conversion efficiency is generally dominated by the dimensionless thermoelectric figure of merit zT.Generally,if the efficiency of thermoelectric devices is to obtain 15%,high zT values averaging at least 1.0 are needed when the temperature difference is 550 K.However,the value of zT in present commercial TE materials is typically less than unity.