Acoustic-Driven Enhancement of Photocarrier Separation in a Reconfigurable WSe ₂ Homojunction

Two-dimensional transition-metal dichalcogenide (TMD) homojunctions are promising for optoelectronic applications but are fundamentally limited by inefficient carrier separation, even under reverse bias. Here, we introduce surface acoustic wave (SAW) technology as an efficient means to enhance photocarrier dissociation via strain-mediated electron-phonon interactions. To experimentally validate this approach, we constructed a hybrid acoustooptic platform by integrating a LiNbO₃ substrate with interdigitated transducers onto a SiO₂/Si chip. A reconfigurable WSe₂ homojunction─fabricated on an hexagonal boron nitride (h-BN) intermediate layer and dynamically tunable via UV-assisted doping to form junctions with tailored built-in potentials─served as the functional device. Under SAW excitation propagating from LiNbO₃ into the device stack, the homojunction exhibits a 30% photocurrent enhancement at 550 nm illumination, outperforming conventional reverse-bias operation at nearly an order-of-magnitude lower voltage, while maintaining a rectification ratio of >10³ and negligible dark-current variation. Mechanistic studies reveal that the SAW induces a type-I band modulation in the nonpiezoelectric heterostructure, creating energy barriers that suppress recombination and substantially improve electron-hole separation. This work demonstrates SAW as an effective strategy for enhancing the optoelectronic performance in homojunctions and provides a scalable platform for acoustooptic applications in nonpiezoelectric low-dimensional systems.