Theoretical exploration of the structural, electronic and optical properties of g-C 3 N 4 /C 3 N heterostructures.

Integration of graphene-like carbon nitride materials is essential for nanoelectronic applications. Using density-functional theory (DFT), we systematically investigate the structural, electronic and optical properties of a s -triazine-based g-C 3 N 4 /C 3 N heterostructure under different modified conditions. The g-C 3 N 4 /C 3 N van der Waals heterostructure (vdWH) formed has an indirect bandgap with type-II band alignment and the band structures can be tuned from type-II band alignment to type-I band alignment by applying biaxial strains and external electric fields ( E field ). Compared to single transition metal (TM) atoms at g-C 3 N 4 /C 3 N surfaces, the TM atoms anchored in the interlayer region exhibit more stability, and the corresponding bandgaps are changed from 0.19 eV to 0.61 eV. In addition, the g-C 3 N 4 /C 3 N heterostructure has a strong absorption coefficient in the ultraviolet-visible light region along the x direction. It is found that compressive strain has a large influence on the absorption coefficient of the g-C 3 N 4 /C 3 N system. With the increased compressive strain, the absorption spectra in the visible light region disappeared. Tensile strain has a slight effect on the absorption range, but causes a red shift of the absorption spectrum. In comparison, the light absorption coefficient of the g-C 3 N 4 /C 3 N system remains almost unchanged under the E field conditions. In summary, the formation of a s -triazine-based g-C 3 N 4 /C 3 N heterostructure has shown potential for applications in nanoelectronic and optoelectronic devices.