Shardul Rai, Abhishek Tewari, Ankit Gupta
The direct conversion of heat into electricity using thermoelectric materials/devices is a promising area of research, offering potential solutions for sustainable energy generation. However, the widespread commercialization remains limited due to the low conversion efficiency. Extensive efforts have been directed towards exploring novel techniques for the development of advanced high-performance thermoelectric materials. One of the most promising outcomes of such efforts is the functional gradation technique. Recent studies on functionally graded thermoelectric materials/devices have been focused on optimizing the figure-of-merit, conversion efficiency, power output and the operating temperature range. The present review summarizes the research conducted in this field over the past decade. It encompasses advanced fabrication methods, performance enhancement and evaluation techniques, theoretical and numerical modelling, and the emerging data-driven approach for fast performance analysis. The concluding remarks outline the key challenges which remain and highlight the future direction to bring functionally graded thermoelectric systems closer to real world application.