Enhanced power factor and high-pressure effects in (Bi,Sb)_2(Te,Se)_3 thermoelectrics

摘要

We investigated the effects of applied high pressure on thermoelectric, electric, structural, and optical properties of single-crystalline thermoelectrics, Bi_2Te_3, Bi_xSb_(2_x)Te_3 (x = 0.4, 0.5, 0.6), and Bi_2Te_(2.73)Se_(0.27) with the high thermoelectric performance. We established that moderate pressure of about 2-4 GPa can greatly enhance the thermoelectric power factor of all of them. X-ray diffraction and Raman studies on Bi_2Te_3 and Bi_(0.5)Sb_(1.5)Te_3 found anomalies at similar pressures, indicating a link between crystal structure deformation and physical properties. We speculate about possible mechanisms of the power factor enhancement and suppose that pressure/stress tuning can be an effective tool for the optimization of the thermoelectric performance.'