Topological Metasurfaces for Ultra‐Broadband Self‐Powered Photodetection With Extremely Strong Light‐Harvesting Capacity

Topological insulator (TI) materials currently attract broad attention for realizing next‐generation electronic and optoelectronic devices due to their fantastic topologically‐protected, semiconducting, and thermoelectric characteristics. However, achieving ultra‐broadband, high‐efficiency, and self‐powered TI photodetectors remains a crucial challenge facing us. Herein, we demonstrated a novel type of topological metasurfaces and realized ultra‐broadband self‐powered photodetection with extremely strong light‐harvesting capacity. The topological metasurfaces are fabricated on the bismuth telluride (Bi 2 Te 3 ) single‐crystal film using focused ion beam lithography, which can present the average light absorption of ∼95.5% covering 300–1700 nm wavelengths with the highest (lowest) absorption efficiency of 99.1% (89.4%). The experiment results agree well with numerical simulations. The ultra‐broad‐spectrum light harvesting is attributed to the excitation of multiple TI‐based optical resonances in the visible and near‐infrared regions. This behavior of the topological metasurface with the intrinsic photothermoelectric effect contributes to the generation of high‐performance self‐powered photocurrent in an ultra‐broad wavelength range. The measurements reveal that the photocurrent of the topological metasurface can approach 5.62 µA at a telecommunication wavelength, which exhibits a 2.9‐fold enhancement compared to that of the Bi 2 Te 3 film. This work will open a new door for exploring cutting‐edge light techniques based on topological materials and their applications in high‐performance optoelectronic devices, especially photodetectors.