Enhancement in figure of merit in N-type Bi(R)-Te thermoelectric nanomaterials

In this paper, we reported the cerium (Ce) doped thermoelectric materials with composition Bi2−xRxTe3 (R = Ce, x = 0.0, 0.1, and 0.2), which were prepared by using different wet chemical methods. The selected synthesis methods that were used included a simplified sol-gel method (Without Water and Surfactants-WOWS) and the Composite Mediated Hydrothermal Method (CMHM). The structural analysis of the samples showed rhombohedral and hexagonal structures. In addition, the surface morphology revealed a flower-like structure for the synthesized samples. The thermal stability was determined using differential scanning calorimetry and thermogravimetric analysis. The electrical conductivity of the samples with a doping ratio of x = 0.1 showed maximum conductivity of (19.10 × 103 (S/cm))-WOWS; (9.10 × 103 (S/cm)) – (CMHM) as compared to than that of other samples (x = 0.0 and 0.2). Interestingly, the doping of Ce increased the Seebeck effect, which also increased the power factor. The power factor of the samples x = 0.1 was higher than that of the undoped samples, which had a magnitude of 12.30 μW/cm.K2 (WOWS) and 7.02 μW/cm.K2 (CMHM). Moreover, we measured the thermal conductivity of the samples using the Advantageous Transient Plane Source (ATPS) method. Therefore, we found the higher figure of merit (ZT) value (0.41) at x = 0.1, which was prepared using a simplified sol-gel method, which is among the highest values that was reported for Bi2−xRxTe3 at room temperature. Because of its potential applications this material has great interest as a thermoelectric material and chip cooling sensing.