Electric-field-induced band reconstruction enables polarity-switchable and spatially programmable photoresponse in PdSe2/2H-MoTe2 van der Waals heterojunction

The strategic orchestration of dual-field synergy, integrating an intrinsic built-in electric field with an external gate-induced vertical field, holds immense promise for achieving reconfigurable photoresponses in two-dimensional van der Waals (vdW) heterojunctions. However, a profound understanding of the interfacial electronic structure evolution, layer-resolved band edge state migration, and spatial distribution modulation mechanisms remains a formidable challenge. Here, we demonstrate a reconfigurable PdSe2/2H-MoTe2 vdW heterojunction through a combined experimental and theoretical strategy. Density functional theory calculations reveal an intrinsically narrow bandgap of ∼0.74 eV and a significant interfacial charge redistribution that establishes a robust built-in field. Crucially, the application of an external vertical field further compresses the bandgap, reconfigures the band edges, and dynamically switches the carrier transport polarity. Experimentally, the fabricated PdSe2/2H-MoTe2 photodetector exhibits an exceptional self-powered broadband response spanning from 405 to 1064 nm, delivering a high responsivity of 64.3 mA/W, a specific detectivity of 9.7 × 1010 Jones, and a sub-millisecond response speed of 340 μs. Comprehensive optoelectronic measurements elucidate that the dual-field synergy significantly amplifies the photoresponse intensity, enabling deterministic photocurrent polarity inversion and spatial shifting of the photocurrent center. This work provides a powerful platform for engineering reconfigurable band alignments, switchable transport kinetics, and programmable intelligent photoresponses.