Independent determination of Peltier coefficient in thermoelectric devices

Abstract

Thermoelectric (TE) generators and coolers are one possible solution to energy autonomy for internet-of-things and biomedical electronics and to locally cool high-performance integrated circuits. The development of TE technology requires not only research into TE materials but also advancing TE device physics, which involves determining properties such as the thermopower (α) and Peltier (Π) coefficients at the device rather than material level. Although Π governs TE cooler operation, it is rarely measured because of difficulties isolating Π from larger non-Peltier heat effects such as Joule heating and Fourier thermal conduction. Instead, Π is almost always inferred from α via a theoretical Kelvin relation Π = αT, where T is the absolute temperature. Here, we demonstrate a method for independently measuring Π on any TE device via the difference in heat flows between the thermopile held open-circuit vs short-circuit. This method determines Π solely from conventionally measured device performance parameters, corrects for non-Peltier heat effects, does not require separate knowledge of material property values, and does not assume the Kelvin relation. A measurement of Π is demonstrated on a commercial Bi2Te3 TE generator. By measuring α and Π independently on the same device, the ratio (Π/α) is free of parasitic thermal impedances, allowing the Kelvin relation to be empirically verified to reasonable accuracy.