Visible-Light-Absorption in Graphitic C3N4 Bilayer: Enhanced by Interlayer Coupling

Although graphitic C3N4 (g-C3N4) has been demonstrated to be a potential candidate for solar cell absorber and photovoltaic materials, the application has been limited by the low photoconversion efficiency in the visible range. Here, we explored that a g-C3N4 bilayer has much better visible-light adsorption than a single layer via first-principles calculations, and the calculated optical adsorption threshold of bilayer significantly shifts downward by 0.8 eV, which is induced by the interlayer coupling. Additionally, we also found that the optical energy gap of bilayer can be engineered by the external electric field. The insights obtained in this study are general and will be helpful for future studies of two-dimensional solar cell absorber and photovoltaic materials.