A BiTe topological insulator/carbon nanotubes hybrid composites as a new counter electrode material for DSSC and NIR photodetector application.

Two-dimensional layered bismuth telluride (BiTe), 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 BiTe and its hybrid nanostructure with single-wall carbon nanotubes (SWCNT) via a straightforward hydrothermal process. The research unveils a novel application for the BiTe-SWCNT hybrid structure, serving as a counter electrode in platinum-free DSSCs, facilitating the conversion of triiodide (I) to iodide (I) and functioning as an active electrode material in a photodetector (n-BiTe-SWCNT/p-Si). The resulting DSSC employing the BiTe-SWCNT hybrid counter electrode achieves a power conversion efficiency (PCE) of 4.2 %, a photocurrent density of 10.5 mA/cm, a fill factor (FF) of 62 %, and superior charge transfer kinetics compared to pristine BiTe based counter electrode (PCE 2.1 %, FF 34 %). Additionally, a spin coating technique enhances the performance of the n-BiTe-SWCNT/p-Si photodetector, yielding a responsivity of 2.2 AW, detectivity of 1.2 × 10 and enhanced external quantum efficiency. These findings demonstrate that the newly developed BiTe-SWCNT heterostructure enhances interfacial charge transport, electrocatalytic performance in DSSCs, and overall photodetector performance.