Photogalvanic Effect in Partially Inverted Janus MoSSe Homostructures with Spontaneous Wrinkles

Two-dimensional (2D) Janus transition-metal dichalcogenides (TMDs) harbor intrinsic strain originating from their asymmetric chalcogen layers, which drives the spontaneous curling, folding, and wrinkling. Such a unique structural property provides an additional degree of freedom for modulating the optoelectronic properties and designing flexible devices. Based on density functional theory (DFT) combined with nonequilibrium Green’s function (NEGF) method, this work systematically constructs and optimizes a series of partially inverted Janus MoSSe nanoribbon homostructures, demonstrating the formation of spontaneous wrinkles, which reduces the formation energy and breaks the spatial symmetry of the initial flat configuration. The strain and its gradient in the wrinkled structure effectively tailor the electronic band structure, leading to an overall upward energy shift and band dispersion modification. The quantum transport simulations reveal that these corrugated structures obviously enhance the photocurrent based on the photogalvanic effect (PGE) compared to the flat structures. The enhancement is not only attributed to the reduction of their symmetry but also to a spatially graded band alignment in the irradiated central region, which improves the separation of photogenerated electron–hole pairs and their subsequent carrier transport toward the electrode. These findings indicate that the partial inversion of chalcogen layers in Janus TMDs extends the design paradigm for property regulation and possesses application potential in advanced self-powered photodetectors.