Negative differential resistance (NDR) in van der Waals heterostructures holds significant potential for high-frequency electronics and logic circuits. This study explores the NDR behavior of n-type MoS2/p-type Sb2Se3 heterostructures. Bulk Sb2Se3 flakes are mechanically exfoliated, exhibiting quasi-1D characteristics due to their anisotropic structure, while MoS2 is synthesized via chemical vapor deposition (CVD) to ensure high crystallinity and uniform layer thickness. The MoS2/Sb2Se3 heterojunction demonstrates a pronounced rectifying behavior alongside two distinct NDR peaks at room temperature. The first NDR peak (NDR-1) originates from band-to-band tunneling (BTBT), whereas the second peak (NDR-2) emerges under laser illumination and is attributed to trap states, intrinsic defects, and carrier recombination dynamics rather than tunneling mechanisms. The application of gate voltage further modulates the NDR characteristics, revealing the intricate interplay between external fields and tunneling mechanisms. Additionally, laser modulation effectively shifts and enhances the NDR peak, highlighting the device’s broad spectral sensitivity from ultraviolet (UV) to near-infrared (NIR) wavelengths. These results demonstrate the viability of MoS2/Sb2Se3
heterostructures for tunable electronic and optoelectronic devices, such as photodetectors and high-speed reconfigurable circuits, where NDR, laser modulation, and gate control play a crucial role in performance optimization.