A Bi₂Te₃ topological insulator/carbon nanotubes hybrid composites as a new counter electrode material for DSSC and...

Two-dimensional layered bismuth telluride (Bi₂Te₃), a prominent topological insulator, has garnered global scientific attention for its unique properties and potential applications in optoelectronics and electrochemical devices. Notably, there is a growing emphasis on improving photon-to-electron conversion efficiency in dye-sensitized solar cells (DSSCs), prompting the exploration of alternatives to noble metal catalysts like platinum (Pt). This study presents the synthesis of Bi₂Te₃ and its hybrid nanostructure with single-wall carbon nanotubes (SWCNT) via a straightforward hydrothermal process. The research unveils a novel application for the Bi₂Te₃-SWCNT hybrid structure, serving as a counter electrode in platinum-free DSSCs, facilitating the conversion of triiodide (I₃^-) to iodide (I^-) and functioning as an active electrode material in a photodetector (n-Bi₂Te₃-SWCNT/p-Si). The resulting DSSC employing the Bi₂Te₃-SWCNT hybrid counter electrode achieves a power conversion efficiency (PCE) of 4.2 %, a photocurrent density of 10.5 mA/cm², a fill factor (FF) of 62 %, and superior charge transfer kinetics compared to pristine Bi₂Te₃ based counter electrode (PCE 2.1 %, FF 34 %). Additionally, a spin coating technique enhances the performance of the n-Bi₂Te₃-SWCNT/p-Si photodetector, yielding a responsivity of 2.2 AW^-1, detectivity of 1.2 × 10^-3 and enhanced external quantum efficiency. These findings demonstrate that the newly developed Bi₂Te₃-SWCNT heterostructure enhances interfacial charge transport, electrocatalytic performance in DSSCs, and overall photodetector performance.