Fabrication of a unipolar Peltier device using a pair of N-type thermoelectric materials

• Our device can operate as a Peltier device with unipolar thermoelectric materials.
• The new Peltier device can be fabricated with addition of a central electric line.
• Unipolar Peltier devices lead to use of many kinds of thermoelectric materials.
• The new Peltier device can give rise to temperature gradient on itself.
• Temperature gradient on the new Peltier device can be changed through currents.

We proposed and fabricated an NN-type Peltier device composed of two small N-type Bi2Se0.37Te2.36 thermoelectric bulk materials. This structure includes an additional electric wire between the two N-type bulks. We introduce an application of the NN-type Peltier device as a stage on which a temperature difference can be induced by altering the current, targeting a rapid amplification system for deoxyribonucleic acid (a thermal cycler for the polymerase chain reaction). The currents in the two circuits differ from each other. The current dependence of the stage temperature of the NN-type Peltier device was investigated and the temperature difference on the stage was 21.4 °C at a current of 24 A. To analyze the device performance, the heat balance for the Peltier device composed of two N-type bulks was obtained by considering the effects of the electric resistance and thermal conductance of the central electric wire between the two N-type materials. The Seebeck coefficient, total resistance, total thermal conductance, and heat absorption were obtained by fitting to be −4.24 × 10−4 V/K, 2.55 × 10−4 Ω, 0.159 W/K, and 1.13 W, respectively, which were in good agreement with those estimated using literature values. Moreover, we fabricated an NN-type thermoelectric power device with a temperature difference of 70 K, an open voltage of 16 V, and a maximum power of 8 mW at a current of 0.9 A.

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