Grape juice: an effective liquid additive for significant enhancement of thermoelectric performance of Cu 2 Se

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 33; pp. 16913 - 16919
• Main Authors: Nazrul Islam, Sheik Md Kazi, Cortie, Michael B., Wang, Xiaolin
• Format: Journal Article
• Language: English
• Published: 25.08.2020
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D0TA03545A

The reduction of thermal conductivity and enhancement of electrical properties is the ultimate goal for achieving high-performance thermoelectric materials. In this paper, a high thermoelectric performance is demonstrated when grape juice is used as an additive to Cu 2 Se. High temperature processing of the mixture pyrolyzes the sugars in the grape juice and provides a fine-scale and well-mixed dispersion of elemental carbon in the Cu 2 Se matrix. These materials show a significant enhancement of electrical conductivity due to a high hole concentration with little change of the Seebeck coefficient, leading to an ultra-high power factor of 1.3 mW m −1 K −2 at 984 K. Microstructural studies reveal that the carbon phase is embedded on the Cu 2 Se grain boundaries and that Cu 2 O nanoparticles are located at the interface between carbon and Cu 2 Se. This results in phonon scattering at the interface which leads to a reduction of thermal conductivity of up to ∼38%. It is proposed that the formation of Cu 2 O also induces Cu deficiencies in Cu 2 Se resulting in greater enhancement of electrical conductivity. As a result, the zT is significantly enhanced up to ∼2.5 at 984 K. This study opens up a new avenue for enhancing the properties of thermoelectric materials.