A Bi 2 Te 3 topological insulator/carbon nanotubes hybrid composites as a new counter electrode material for DSSC and NIR photodetector application.

Two-dimensional layered bismuth telluride (Bi ₂ Te ₃ ), 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 ₂ Te ₃ and its hybrid nanostructure with single-wall carbon nanotubes (SWCNT) via a straightforward hydrothermal process. The research unveils a novel application for the Bi ₂ Te ₃ -SWCNT hybrid structure, serving as a counter electrode in platinum-free DSSCs, facilitating the conversion of triiodide (I ₃ ^- ) to iodide (I ^- ) and functioning as an active electrode material in a photodetector (n-Bi ₂ Te ₃ -SWCNT/p-Si). The resulting DSSC employing the Bi ₂ Te ₃ -SWCNT hybrid counter electrode achieves a power conversion efficiency (PCE) of 4.2 %, a photocurrent density of 10.5 mA/cm ² , a fill factor (FF) of 62 %, and superior charge transfer kinetics compared to pristine Bi ₂ Te ₃ based counter electrode (PCE 2.1 %, FF 34 %). Additionally, a spin coating technique enhances the performance of the n-Bi ₂ Te ₃ -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 ₂ Te ₃ -SWCNT heterostructure enhances interfacial charge transport, electrocatalytic performance in DSSCs, and overall photodetector performance.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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