Recent advances in two-dimensional transition metal oxides and di-chalcogenides as efficient thermoelectric materials

Abstract Designing of efficient thermoelectric material is the need of hour to avoid the adverse effect on environment. Two-dimensional (2D) transition metal oxides (TMOs) and transition metal dichalogenides (TMDCs) are receiving attention of researchers due to their wide range of electronic properties, high temperature and air stability, tunable electron transport properties for high thermoelectric efficiency (ZT). Two- dimensionalization in these materials lead to the increase in their thermoelectric efficiency as compared to their bulk counterpart due to the quantum confinement effect. These materials possess high thermoelectric efficiency even at high temperature (500–800 K) but their application still lagging behind commercially due to low ZT value. Various approaches such as strain engineering, defect engineering etc. Were adopted to further enhance the ZT value of these materials. Controlling chalcogen atomic defect provides an alternative avenue for engineering a wide range of physical and chemical properties of 2D TMOs/TMDCs. In this review we will systematically present the progress made in the study of electronic, phononic, transport properties and Seebeck coefficient of 2D TMOs/TMDCs such as XO 2 (X=Cr, Mo, Zr) and MX 2 (M= Cr, Mo, Zr; X= S, Se, Te) by using first principle approach. Methodologies such as strain engineering and doping to enhance the ZT values has also been discussed. In the last section we have discussed the experimental results of thermoelectric parameters of TMDCs and compare them with the existing theoretical results. It is concluded from this study that there are plenty of rooms which can be explored both theoretically and experimentally to design efficient thermoelectric materials for energy harvesting.