Self-tuning of carrier concentration for high thermoelectric performance
View Patent ↗The inventors demonstrate herein that homogeneous Ag-doped PbTe/Ag 2 Te composites exhibit high thermoelectric performance (˜50% over La-doped composites) associated with an inherent temperature induced gradient in the doping concentration caused by the temperature-dependent solubility of Ag in the PbTe matrix. This method provides a new mechanism to achieve a higher thermoelectric efficiency afforded by a given material system, and is generally applicable to other thermoelectric materials.
1. A composition comprising excess dopant, wherein: (1) the composition comprises PbTe/Ag 2 Te; (2) the excess dopant comprises Ag; and (3) the excess dopant has an increasing solubility limit with increasing temperature (T).
2. The composition of claim 1 , wherein the increasing solubility limit with increasing T is within a temperature range of high thermoelectric performance.
3. The composition of claim 1 , wherein the composition has a dimensionless figure of merit (zT) of no less than 1.4 at 750 K.
4. The composition of claim 1 , wherein the temperature-dependent solubility limit of the dopant in the composition results in an increase in carrier concentration (n) with increasing T.
5. The composition of claim 1 , wherein the composition is represented by a formula: (Ag x PbTe) 0.945 (Ag 2 Te) 0.055 .
6. The composition of claim 5 , wherein 0.005≦x≦0.1.
7. A method of using a composition comprising PbTe/Ag 2 Te in a thermoelectric device, wherein: (1) the composition comprises excess dopant; (2) the excess dopant comprises Ag; and (3) the excess dopant has an increasing solubility limit with increasing temperature (T), within a temperature range of high thermoelectric performance.
8. The method of claim 7 , further comprising: applying a temperature gradient to the thermoelectric device; and collecting electrical energy.
9. The method of claim 7 , wherein the composition has a dimensionless figure of merit (zT) of no less than 1.4 at 750K.
10. The method of claim 7 , wherein the temperature-dependent solubility limit of the dopant in the composition results in an increase in carrier concentration (n) with increasing temperature (T).
11. The method of claim 7 , wherein the composition is represented by a formula: (Ag x PbTe) 0.945 (Ag 2 Te) 0.055 .
12. The method of claim 11 , wherein 0.005≦x≦0.1.