Configuration-Selective Photocurrent Enhancement Induced by Static Domain Walls in Two-Dimensional Ferroelectric...

Domain walls (DWs) are ubiquitous topological defects in two-dimensional (2D) ferroelectric materials, yet their static role in optoelectronic transport remains unclear. Here, we address this issue using first-principles quantum-transport calculations on monolayer ferroelectric In₂Se₃ p-i-n junctions. Contrary to the conventional view that defects degrade device performance, only specific static DW configurations-not all-can significantly enhance photocurrent. We examine two thermodynamically stable configurations (the Initial and Final states) and one saddle-point configuration (the Transition state) along the polarization-switching pathway. The Initial state yields a photocurrent density of 10.91 μA·mm^-2, about 1.80 times that of the single-domain device, while the Final state reaches 8.39 μA·mm^-2, corresponding to an increase of ~37%. By comparison, the thermodynamically unstable Transition state gives a lower value of 5.92 μA·mm^-2, indicating strong configuration selectivity. Analysis shows that the observed behavior can be qualitatively rationalized by the combined effects of optical absorption, carrier separation induced by DW-driven electrostatic-potential redistribution, and preserved conduction-channel continuity for carrier extraction. These findings provide a microscopic basis for understanding configuration-selective photocurrent enhancement by static domain walls in short-channel 2D ferroelectric devices.