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 (Bi₂Te₃) 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 Bi₂Te₃ 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.