Two-Dimensional Ferroelectric C₂N/In₂Se₃ Heterobilayer with Tunable Electronic Property and Photovoltaic Effect

Two-dimensional ferroelectric monolayer materials with reversible spontaneous polarization provide more regulatory dimensions for their relevant van der Waals heterostructures. Using first-principles calculations, we construct the C₂N/In₂Se₃ bilayer heterostructure and study its physical properties as well as the effects of E-field and strain. The results indicate that the intrinsic polarization of the component In₂Se₃ monoalyer can significantly adjust the electronic properties of the C₂N/In₂Se₃ heterobilayer. When the polarization of the In₂Se₃ monolayer points to the interface (up-In₂Se₃), the C₂N/In₂Se₃ bilayer behaves as the type-I indirect band gap heterostructure, while it transforms to the type-II direct band gap heterostructure after reversing the polarization of the In₂Se₃ monolayer (dp-In₂Se₃). Furthermore, the two C₂N/In₂Se₃ heterostructures both have enhanced optical absorption in the visible region than the isolated In₂Se₃ and C₂N monolayers. More importantly, the external electric field and strain can easily regulate the electronic properties of the C₂N/In₂Se₃ heterostructures. The power conversion efficiency (PCE) of the type-II C₂N/dp-In₂Se₃ heterostructure is 8.16%, and the electric field of 0.1 V/Å and the strain of -2% can transform the C₂N/up-In₂Se₃ heterostructure into type-II one, conducive to the high PCE up to 24.03 and 24%, respectively. Our proposed C₂N/In₂Se₃ heterostructure is promising in future luminescent and photovoltaic fields, and our findings also provide a strategy for functionalizing 2D monolayer materials by the intrinsic polarization property of ferroelectric materials.