Strain‐Induced Piezo‐Optoelectronic Coupling in Monolayer MoS₂

Piezo-optoelectronic coupling, the direct modulation of photoresponse by strain-induced piezoelectric polarization, is a theoretically promising route to adaptive, programmable optoelectronics, yet it remains experimentally elusive in scalable two-dimensional systems. Here, we present large-area monolayer MoS₂ as a robust platform for probing and controlling this coupling at the atomic limit, and a single device made on it demonstrates integrated functionality for energy generation, strain sensing, and photodetection within a unified configuration. Using dual AC resonance tracking piezoresponse force microscopy, we quantify an out-of-plane piezoelectric coefficient (dᵉᶠᶠ₃₃ = 0.64 pm/V) and demonstrate a pronounced, strain-tunable internal piezoelectric polarization that enables exciton dissociation under low bias and illumination, distinct from conventional photodetection approaches. While absolute responsivity is modest, the observed strain-induced enhancement of photocurrent and the clear correlation with measured piezoresponse reveal that mechanical deformation can be leveraged as a precise control knob for charge separation and light–matter interaction in ultrathin semiconductors. These findings provide direct experimental insight into piezo-optoelectronic coupling, establishing monolayer MoS₂ as a multifunctional and scalable platform for future studies of coupled electromechanical photonic phenomena and for the development of programmable optoelectronics, hybrid sensors, and next-generation flexible devices.