Intrinsic photovoltaic characteristics of WS2 photodiode via a transparent and pinning-free van der Waals 2D metal

Transition metal dichalcogenides offer promising opportunities for optoelectronic devices owing to tunable bandgaps and strong light-matter interactions; however, device performance is often hindered by Fermi-level pinning at metal–semiconductor interfaces. Two-dimensional (2D) metals have emerged as an effective strategy to mitigate this issue; however, a systematic comparison of their optoelectronic performance under a unified device architecture has remained incompletely explored. Here, we demonstrate that 2D metals form nearly defect-free and pinning-free contacts with WS 2 , as evidenced by photoluminescence characterization and Schottky barrier height extraction, enabling near-ideal Schottky barrier alignment. Through a statistical analysis of multiple 2D metals, we elucidate how their work functions govern the resulting optoelectronic properties. By employing Cl–SnSe 2 as a transparent 2D metal contact, we achieve exceptional optoelectronic performance with a linear dynamic range of 135 dB and a power conversion efficiency of 13.6%. Furthermore, we implement in-sensor image processing, revealing the distinct performance of 2D metal contacts over conventional bulk metals. These results highlight the critical role of contact engineering in 2D semiconductor devices and provide a viable pathway toward high-performance optoelectronic systems.