Screening thermoelectric materials for high-output performance in wearable electronics†

Abstract

Thermoelectric (TE) technology provides a promising self-powered solution for wearable electronics and the Internet of Things (IoT), but the output voltage density and power density of current TE devices remain far below the target values required 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 proposed that |S|/κ and S²σ/κ² were more effective indicators for screening TE materials for the development of high-performance TE devices for use in the exacting working conditions (e.g., windless indoor environments and extremely limited space) of wearable electronics and the IoT. As a case study, both simulations and experiments were performed and clearly demonstrated that the TE device consisting of n-type Ag_1.995Au_0.005Te_0.7S_0.3 and p-type Ag_0.9Sb_1.1Te_2.1 with high |S|/κ and S²σ/κ² values achieved higher output performance than the Bi₂Te₃-based TE device. When the Ag_1.995Au_0.005Te_0.7S_0.3/Ag_0.9Sb_1.1Te_2.1 TE device was worn on the human wrist, a record-high voltage density and power density were achieved. This work provides new insight into the development of advanced TE devices for wearable electronics and the IoT.