Efficient Zn-based pn-junction thermoelectric device for energy harvesting

• Published in: Journal of materials science. Materials in electronics Vol. 35; no. 4; p. 263
• Main Authors: Banupriya, L., Emerson, R. N., Bala, G. Josemin
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2024; Springer Nature B.V
• Subjects: Adhesive strength; Characterization and Evaluation of Materials; Chemistry and Materials Science; Dehydration; Energy consumption; Energy harvesting; Figure of merit; Glass substrates; Graphs; Materials Science; Maximum power; Optical and Electronic Materials; Power factor; Seebeck effect; Surface roughness; Thermal conductivity; Thermoelectricity; Thin films; Waste heat recovery; Zinc acetate; Zinc oxide
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-024-12014-8

This paper proposes a novel pn-junction thermoelectric device to improve the conversion of thermoelectric energy. The device was created by depositing films of p-type Zn-doped CuI and n-type Al-doped ZnO onto an ITO glass substrate using electrodeposition technique. The resulting films had a smooth surface with nano-sized grains. They also exhibited strong adhesion at − 1.2 V compared to Ag/AgCl when 5 mol% of zinc acetate dehydrate was used. The UV-visible graphs revealed that both films had an average band gap of 3 eV. X-ray graphs showed that the thin films were highly crystalline, with orientations symmetrically arranged in the (1 0 2) and (2 2 0) planes. AFM images showed that both films have highly crystalline surface and their surface roughness favours strong adhesion. These high conductive films exhibited thermoelectric energy, which was calculated using the Seebeck effect. The hot probe method showed that the p-type Zn-CuI and n-type AZO thin films were dense and exhibited a thermoelectric figure of merit (ZT) of 0.40 and 0.50 up to the temperature of 120 °C. The thermal conductivity of the p-type and n-type materials was determined to be 2.23 W m −1 K −1 and 12.65 W m −1 K −1 , respectively. The power factor of the p and n films was found to be 202.74 µW m −1  K −2 and 525.51 µW m −1  K −2 , respectively. This was followed by the fabrication of a Zn-based thermoelectric device using a single pair of p-type Zn-CuI and n-type AZO thin-film legs. The fabricated thermoelectric device generated a maximum power of 117 pW. This Zn-based thermoelectric device is highly effective for waste heat recovery and can efficiently accumulate useful electricity over time, thereby prolonging battery life.