Screening thermoelectric materials for high output performance in wearable electronics

Thermoelectric (TE) technology provides a promising self-powered solution to the wearable electronics and Internet of Things (IoT), but the output voltage density and power density of current TE devices are still far below the target values for practical use. In this work, instead of the commonly used TE figure-of-merit (zT = S2σ/κT, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature), we propose that |S|/κ and S2σ/κ2are more effective indicators to screen the TE materials for the development of powerful TE devices used in the exacting working conditions (e.g. windless indoor environment and extremely limited space) for wearable electronics and IoT. As a case study, both the simulation and experiment well prove that the TE device consisting of n-type Ag1.995Au0.005Te0.7S0.3 and p-type Ag0.9Sb1.1Te2.1 with high |S|/κ and S2σ/κ2 can achieve higher output performance than the Bi2Te3-based TE device. When the Ag1.995Au0.005Te0.7S0.3/Ag0.9Sb1.1Te2.1 TE device is worn on human wrist, record-high voltage density and power density are achieved. This work brings a new insight to the development of advanced TE devices used for the wearable electronics and IoT.