Bismuth telluride-based thermoelectric generators: advances in synthesis, performance enhancement, and device applications

Thermoelectric (TE) devices are increasingly recognised for their ability to convert waste heat into electricity, offering a sustainable solution for low-power energy harvesting. Among TE materials, bismuth telluride (Bi₂Te₃)-based compounds demonstrate outstanding performance at room temperature (RT), making them ideal candidates for thermoelectric generators (TEGs). Recent research has focused on enhancing the TE properties of Bi₂Te₃-based materials, particularly through doping strategies, although the mechanisms underlying these improvements remain underexplored. Additionally, the mechanical performance of Bi₂Te₃-based materials, which is vital for practical applications, has only recently received attention. This review summarises the developments in Bi₂Te₃-based TE materials over the past decade, including general synthesis techniques for bulk and thin-film materials, as well as doping and other methods to enhance the TE performance. It also assesses the mechanical and TE performance of Bi₂Te₃-based devices, highlighting their novel designs, durability, flexibility and efficiency in various application ranging from the energy harvesting, thermal management and sensing applications. Strategies such as material doping and thermal annealing have been discussed for their potential to optimise TE properties. The TE conversion efficiencies of Bi₂Te₃-based TEGs generally range from 6 % to 7 %. Future research should focus on refining these methods, exploring combined strategies and optimisation of each preparation steps, and improving design parameters to boost performance while ensuring device sustainability and long-term flexibility under thermal and mechanical cycles.