Two-dimensional layered bismuth telluride (Bi<inf>2</inf>Te<inf>3</inf>), 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 Bi<inf>2</inf>Te<inf>3</inf> and its hybrid nanostructure with single-wall carbon nanotubes (SWCNT) via a straightforward hydrothermal process. The research unveils a novel application for the Bi<inf>2</inf>Te<inf>3</inf>-SWCNT hybrid structure, serving as a counter electrode in platinum-free DSSCs, facilitating the conversion of triiodide (I<inf>3</inf>−) to iodide (I−) and functioning as an active electrode material in a photodetector (n-Bi<inf>2</inf>Te<inf>3</inf>-SWCNT/p-Si). The resulting DSSC employing the Bi<inf>2</inf>Te<inf>3</inf>-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 Bi<inf>2</inf>Te<inf>3</inf> based counter electrode (PCE 2.1 %, FF 34 %). Additionally, a spin coating technique enhances the performance of the n-Bi<inf>2</inf>Te<inf>3</inf>-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 Bi<inf>2</inf>Te<inf>3</inf>-SWCNT heterostructure enhances interfacial charge transport, electrocatalytic performance in DSSCs, and overall photodetector performance. © 2024 Elsevier B.V., All rights reserved.