Heavy Doping and Band Engineering by Potassium to Improve the Thermoelectric Figure of Merit in p-Type PbTe, PbSe, and PbTe1鈥?i>ySey

详细信息    查看全文

• 作者：Qian Zhang ; Feng Cao ; Weishu Liu ; Kevin Lukas ; Bo Yu ; Shuo Chen ; Cyril Opeil ; David Broido ; Gang Chen ; Zhifeng Ren
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：June 20, 2012
• 年：2012
• 卷：134
• 期：24
• 页码：10031-10038
• 全文大小：539K
• 年卷期：v.134,no.24(June 20, 2012)
• ISSN：1520-5126

文摘

We present detailed studies of potassium doping in PbTe_1鈥?i>ySe_y (y = 0, 0.15, 0.25, 0.75, 0.85, 0.95, and 1). It was found that Se increases the doping concentration of K in PbTe as a result of the balance of electronegativity and also lowers the lattice thermal conductivity because of the increased number of point defects. Tuning the composition and carrier concentration to increase the density of states around the Fermi level results in higher Seebeck coefficients for the two valence bands of PbTe_1鈥?i>ySe_y. Peak thermoelectric figure of merit (ZT) values of 1.6 and 1.7 were obtained for Te-rich K_0.02Pb_0.98Te_0.75Se_0.25 at 773 K and Se-rich K_0.02Pb_0.98Te_0.15Se_0.85 at 873 K, respectively. However, the average ZT was higher in Te-rich compositions than in Se-rich compositions, with the best found in K_0.02Pb_0.98Te_0.75Se_0.25. Such a result is due to the improved electron transport afforded by heavy K doping with the assistance of Se.