Type-III SnO₂/SnSe₂ metal heterostructure as an intrinsic transparent conductor

Conventional transparent conductors (TCs) commonly rely on parity-forbidden optical transitions to suppress interband absorption and achieve optical transparency. A recently proposed design strategy based on wavefunction-isolated forbidden transitions has shown initial promise. However, its realization has so far been limited to materials with exotic electronic structures, such as electrides. We found that the valence and conduction bands (VBs and CBs) in type-II and type-III heterostructures originate from different constituent materials, which naturally leads to the spatial separation of wavefunctions. This configuration provides an effective framework for implementing the wavefunction-isolated forbidden transition strategy in design of intrinsic TCs. In this work, we constructed a SnO₂/SnSe₂ heterostructure. First-principles calculations reveal that the heterostructure exhibits a metallic band structure with a type-III band alignment, while the spatial separation of wavefunctions between SnO₂ and SnSe₂ layers suppresses interband transitions, resulting in an average transparency of approximately 70% in the visible spectrum for a freestanding 100 nm thick film. Moreover, interfacial charge accumulation significantly enhances the electrical conductivity. These results demonstrate the feasibility of realizing wavefunction-isolated forbidden transition TCs through heterostructure engineering and suggest that heterostructures with suitable band alignment and moderate interfacial coupling provide a promising route for designing intrinsic TCs from conventional materials.