Effective Mass Enhancement and Thermal Conductivity Reduction for Improving the Thermoelectric Properties of Pseudo-Binary Ge2Sb2Te5

Ge2Sb2Te5 is a famous phase-change memory material for rewriteable optical storage, which is widely applied in the information storage field. The stable trigonal phase of Ge2Sb2Te5 shows potential as a thermoelectric material as well, due to its tunable electrical transport properties and low lattice thermal conductivity. In this work, the carrier concentration and effective mass of Ge2Sb2Te5 are modulated by substituting Te with Se. Meanwhile, the thermal conductivity reduces from 2.48 W m(-1) K-1 for Ge2Sb2Te5 to 1.37 W m(-1) K-1 for Ge2Sb2Te3.5Se1.5 at 703 K. Therefore, the thermoelectric figure of merit zT increases from 0.24 for Ge2Sb2Te5 to 0.41 for Ge2Sb2Te3.5Se1.5 at 703 K. This study reveals that Se alloying is an effective way to enhance the thermoelectric properties of Ge2Sb2Te5.