Thickness‐Engineered 2D NbSe ₂ /SnS ₂ Nanosheet Heterostructures for Enhanced Self‐Powered Broadband Photodetection

ABSTRACT Low‐dimensional materials have garnered significant interest for their unique structural attributes and exceptional intrinsic properties, making them highly promising candidates for a wide range of electronic and optoelectronic applications. Their high surface‐to‐volume ratio and distinctive geometries are particularly advantageous in energy‐related technologies, including supercapacitors, lithium‐ion batteries, and advanced photodetectors. These characteristics have propelled their use in developing next‐generation broadband photodetectors with enhanced performance. In this work, we present self‐powered broadband photodetectors based on thickness‐modulated NbSe ₂ /SnS ₂ heterostructures synthesized via a hydrothermal method. Among the fabricated devices, the heterostructure incorporating trilayer NbSe ₂ /SnS ₂ exhibited superior photodetection performance. Specifically, the device achieved exceptional responsivities of 11.75, 45.37, 25.92, 10.27, and 10.01 AW ⁻¹ at illumination wavelengths of 365, 456, 532, 632, and 850 nm, respectively, under zero bias. Correspondingly, high detectivity values of 1.97 × 10 ¹¹ , 3.40 × 10 ¹¹ , 1.37 × 10 ¹¹ , 0.45 × 10 ¹¹ , and 0.38× 10 ¹¹ Jones were recorded, respectively. The trilayer NbSe ₂ /SnS ₂ device exhibited fast photoresponse with a 42 ms rise and 83 ms fall time, attributed to the high conductivity and potential superconductivity of the NbSe ₂ layer. These findings highlight the significant potential of engineered low‐dimensional heterostructures in the development of next‐generation, self‐powered optoelectronic systems and environmentally sustainable photodetection technologies.