TY - JOUR
T1 - Ultrahigh thermoelectric performance in Cu2−ySe0.5S0.5 liquid-like materials
AU - Zhao, Kunpeng
AU - Qui, Pengfei
AU - Song, Qingfeng
AU - Blichfeld, Anders Bank
AU - Eikeland, Espen Zink
AU - Ren, Dudi
AU - Ge, Binghui
AU - Iversen, Bo Brummerstedt
AU - Shi, Xun
AU - Chen, Lidong
PY - 2017/6
Y1 - 2017/6
N2 - Liquid-like thermoelectric materials have recently received heightened attentions due to their exceptional thermal and electrical transport properties. As a typical example, Cu
2−ySe has good electrical transport properties while Cu
2−yS has extremely low lattice thermal conductivity. Combining these stirring characters into one material is expected to result in excellent thermoelectric performance. In this study, we found that Cu
2−ySe and Cu
2−yS can form a solid solution in the composition range down to half Se and half S. XRD, SEM and TEM reveal that Cu
2−ySe
0.5S
0.5 possesses a unique hierarchical microstructure composed of mesoscale polymorphs, nanoscale domains and modulations. Besides, the liquid-like copper ions at high temperature not only strongly scatter lattice phonons but also eliminate some of the transverse phonon vibrations. Combining with the extraordinarily low sound speeds, an overall ultralow thermal conductivity is achieved in Cu
2−ySe
0.5S
0.5 with the values similar to that in Cu
2S. Furthermore, the electrical transport performance of Cu
2−ySe
0.5S
0.5 is significantly improved through tuning its native Cu vacancies. High electrical power factors similar to or even superior to Cu
2−ySe are observed due to the high weighted mobility. All these favorable factors lead to much enhanced quality factor and thus remarkably high thermoelectric performance in Cu
2−ySe
0.5S
0.5, which reaches a ZT of 2.3 at 1000 K, among the highest values in bulk materials.
AB - Liquid-like thermoelectric materials have recently received heightened attentions due to their exceptional thermal and electrical transport properties. As a typical example, Cu
2−ySe has good electrical transport properties while Cu
2−yS has extremely low lattice thermal conductivity. Combining these stirring characters into one material is expected to result in excellent thermoelectric performance. In this study, we found that Cu
2−ySe and Cu
2−yS can form a solid solution in the composition range down to half Se and half S. XRD, SEM and TEM reveal that Cu
2−ySe
0.5S
0.5 possesses a unique hierarchical microstructure composed of mesoscale polymorphs, nanoscale domains and modulations. Besides, the liquid-like copper ions at high temperature not only strongly scatter lattice phonons but also eliminate some of the transverse phonon vibrations. Combining with the extraordinarily low sound speeds, an overall ultralow thermal conductivity is achieved in Cu
2−ySe
0.5S
0.5 with the values similar to that in Cu
2S. Furthermore, the electrical transport performance of Cu
2−ySe
0.5S
0.5 is significantly improved through tuning its native Cu vacancies. High electrical power factors similar to or even superior to Cu
2−ySe are observed due to the high weighted mobility. All these favorable factors lead to much enhanced quality factor and thus remarkably high thermoelectric performance in Cu
2−ySe
0.5S
0.5, which reaches a ZT of 2.3 at 1000 K, among the highest values in bulk materials.
KW - Electrical conductivity
KW - Liquid-like
KW - Quality factor
KW - Thermal conductivity
KW - Thermoelectric
UR - http://www.scopus.com/inward/record.url?scp=85027346267&partnerID=8YFLogxK
U2 - 10.1016/j.mtphys.2017.04.003
DO - 10.1016/j.mtphys.2017.04.003
M3 - Journal article
SN - 2542-5293
VL - 1
SP - 14
EP - 23
JO - Materials Today Physics
JF - Materials Today Physics
ER -