Giant Photoresponse in 2D Layered Semiconductors Enabled by Long-Range Exciton-Polaritons

Abstract Photodetection constitutes a fundamental building block underpinning modern optical communication, imaging, and sensing systems. Atomically thin transition metal dichalcogenides have emerged as promising candidates for next-generation photodetection devices due to their exceptional excitonic resonance and unparalleled compatibility with on-chip integration. However, their photodetection performance remains severely limited by low optical absorption and short carrier diffusion distances. Here, we demonstrate an enhanced photodetection exceeding 60 folds in a broad frequency region for the bilayer WS2 integrated on a truncated one-dimensional photonic crystal. The formation of Bloch surface wave polaritons enables a high-speed and long-range propagation, accelerating efficient photoelectric conversion. By systematically investigating the photocurrent response of WS2 under different photonic environments, the distinct contributions from excitation enhancement and polaritonic effects are clearly revealed. Notably, correlating the spatially resolved photocurrent and the polariton transport directly confirms the enhancement contributions from the long-range polaritons and the modified Schottky barrier. These results not only offer a novel strategy for chip-scale efficient photon detection based on 2D materials but also provide a versatile platform to explore polaritonic optoelectronics.