Abstract
High ZT of 1.34 at 766 K and a record high average ZT above 1 in the temperature range of 300-864 K are attained in n-type PbTe by engineering the temperature-dependent carrier concentration and weakening electron-phonon coupling upon Ga doping. The experimental studies and first principles band structure calculations show that doping with Ga introduces a shallow level impurity contributing extrinsic carriers and imparts a deeper impurity level that ionizes at higher temperatures. This adjusts the carrier concentration closer to the temperature-dependent optimum and thus maximizes the power factor in a wide temperature range. The maximum power factor of 35 μW cm-1 K-2 is achieved for the Pb0.98Ga0.02Te compound, and is maintained over 20 μWcm-1 K-2 from 300 to 767 K. Band structure calculations and X-ray photoelectron spectroscopy corroborate the amphoteric role of Ga in PbTe as the origin of shallow and deep levels. Additionally, Ga doping weakens the electron-phonon coupling, leading to high carrier mobilities in excess of 1200 cm2 V-1 s-1. Enhanced point defect phonon scattering yields a reduced lattice thermal conductivity. This work provides a new avenue, beyond the conventional shallow level doping, for further improving the average ZT in thermoelectric materials.
| Original language | English |
|---|---|
| Journal | Advanced Energy Materials |
| DOIs | |
| Publication status | Accepted/In press - Jan 1 2018 |
Fingerprint
Keywords
- Deep level impurities
- Ga doping
- PbTe
- Thermoelectric properties
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
Cite this
Weak Electron Phonon Coupling and Deep Level Impurity for High Thermoelectric Performance Pb1-xGaxTe. / Su, Xianli; Hao, Shiqiang; Bailey, Trevor P.; Wang, Si; Hadar, Ido; Tan, Gangjian; Song, Tze Bin; Zhang, Qingjie; Uher, Ctirad; Wolverton, Chris; Tang, Xinfeng; Kanatzidis, Mercouri G.
In: Advanced Energy Materials, 01.01.2018.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Weak Electron Phonon Coupling and Deep Level Impurity for High Thermoelectric Performance Pb1-xGaxTe
AU - Su, Xianli
AU - Hao, Shiqiang
AU - Bailey, Trevor P.
AU - Wang, Si
AU - Hadar, Ido
AU - Tan, Gangjian
AU - Song, Tze Bin
AU - Zhang, Qingjie
AU - Uher, Ctirad
AU - Wolverton, Chris
AU - Tang, Xinfeng
AU - Kanatzidis, Mercouri G
PY - 2018/1/1
Y1 - 2018/1/1
N2 - High ZT of 1.34 at 766 K and a record high average ZT above 1 in the temperature range of 300-864 K are attained in n-type PbTe by engineering the temperature-dependent carrier concentration and weakening electron-phonon coupling upon Ga doping. The experimental studies and first principles band structure calculations show that doping with Ga introduces a shallow level impurity contributing extrinsic carriers and imparts a deeper impurity level that ionizes at higher temperatures. This adjusts the carrier concentration closer to the temperature-dependent optimum and thus maximizes the power factor in a wide temperature range. The maximum power factor of 35 μW cm-1 K-2 is achieved for the Pb0.98Ga0.02Te compound, and is maintained over 20 μWcm-1 K-2 from 300 to 767 K. Band structure calculations and X-ray photoelectron spectroscopy corroborate the amphoteric role of Ga in PbTe as the origin of shallow and deep levels. Additionally, Ga doping weakens the electron-phonon coupling, leading to high carrier mobilities in excess of 1200 cm2 V-1 s-1. Enhanced point defect phonon scattering yields a reduced lattice thermal conductivity. This work provides a new avenue, beyond the conventional shallow level doping, for further improving the average ZT in thermoelectric materials.
AB - High ZT of 1.34 at 766 K and a record high average ZT above 1 in the temperature range of 300-864 K are attained in n-type PbTe by engineering the temperature-dependent carrier concentration and weakening electron-phonon coupling upon Ga doping. The experimental studies and first principles band structure calculations show that doping with Ga introduces a shallow level impurity contributing extrinsic carriers and imparts a deeper impurity level that ionizes at higher temperatures. This adjusts the carrier concentration closer to the temperature-dependent optimum and thus maximizes the power factor in a wide temperature range. The maximum power factor of 35 μW cm-1 K-2 is achieved for the Pb0.98Ga0.02Te compound, and is maintained over 20 μWcm-1 K-2 from 300 to 767 K. Band structure calculations and X-ray photoelectron spectroscopy corroborate the amphoteric role of Ga in PbTe as the origin of shallow and deep levels. Additionally, Ga doping weakens the electron-phonon coupling, leading to high carrier mobilities in excess of 1200 cm2 V-1 s-1. Enhanced point defect phonon scattering yields a reduced lattice thermal conductivity. This work provides a new avenue, beyond the conventional shallow level doping, for further improving the average ZT in thermoelectric materials.
KW - Deep level impurities
KW - Ga doping
KW - PbTe
KW - Thermoelectric properties
UR - http://www.scopus.com/inward/record.url?scp=85047542088&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85047542088&partnerID=8YFLogxK
U2 - 10.1002/aenm.201800659
DO - 10.1002/aenm.201800659
M3 - Article
AN - SCOPUS:85047542088
JO - Advanced Energy Materials
JF - Advanced Energy Materials
SN - 1614-6832
ER -