Achieving High Thermoelectric Performance in Bi₂(Te, Se)₃ Thin Film with (00 l)-Oriented by Incorporating Tellurization and Selenization Processes

Flexible thermoelectric (TE) generators have received great attention as a sustainable and reliable option to convert heat from the human body and other ambient sources into electricity. This study provides a synthesis route that involves thermally induced diffusion to introduce Te and Se into Bi, fabricating an n-type Bi-Te-Se flexible thin film on a flexible substrate. This specific synthesis alters the crystal orientation (00l) of the thin film, improving in-plane electrical transportation and optimizing carrier concentration. Consequently, Bi_xTe_ySe_0.42 enhanced both the Seebeck coefficient and electrical conductivity, achieving a power factor of 17.1 μW cm^-1 K^-2 at room temperature. The TE device assembled with p-type Sb₂Te₃ exhibited exceptional flexibility with only a 26.2% change in resistance after 1000 times of bending at a radius of about 6 mm. The resistance change was further reduced to 7.5% after the application of a vinyl laurate coating. The fabricated TE device generated an ultrahigh output power of 792 nW with a temperature difference of 30 K.