Organic-Inorganic Hybrid Thermocouple Intended for Thermoelectric Generators Using Low-Cost Nontoxic Materials

Thermoelectricity, which converts heat energy directly into electricity, can be utilized as a waste heat recovery mechanism as well as an alternative energy resource. The thermoelectric generators (TEGs) consist of an array of p-n junctions made of two different thermoelectric materials (TEMs). TEGs can create a potential difference as a result of a temperature difference applied across the junction. Widely used and the best-known TEMs such as Bi2Te3 and Sb2Te3 are hazardous in nature. Therefore, there is an emerging need to search for new non-toxic TEMs. This study investigates the thermal, electrical, and thermoelectric properties of organic polyaniline (PANI) and the inorganic ceramic zinc oxide (ZnO). Further, it is extended to fabricate an organic/inorganic p-n junction suitable for hybrid TEGs using PANI and ZnO. Electrical conductivity and thermal conductivity of PANI, ZnO, and Al-doped ZnO (Al-ZnO) and the Seebeck coefficient, figures of merit and power factors of respective thermocouples were investigated. Fourier transform infrared spectroscopy and x-ray diffraction spectra confirmed the successful synthesis of PANI, ZnO, and Al-ZnO. The temperature-dependent electrical conductivity of all the compounds exhibits a semiconductor behavior. The temperature-dependent Seebeck coefficient of PANI and Al-ZnO are consistent with the values reported in the literature. However, ZnO showed a deviation. The PANI-ZnO thermocouple generated a potential difference of 21.16 mV at a temperature difference of 77 K and these materials indicate promising prospects of nontoxic and low-temperature TEMs. [GRAPHICS] .