Tuning the Electronic and Optical Properties of Two-Dimensional Graphene-like $$\hbox {C}_2\hbox {N}$$ C 2 N Nanosheet by Strain Engineering

Using density functional theory, we have studied the structural, electronic and optical properties of two-dimensional graphene-like $$\hbox {C}_2\hbox {N}$$ nanosheet under in-plane strains. Our results indicate that the $$\hbox {C}_2\hbox {N}$$ nanosheet is a semiconductor with a direct band gap of 1.70 eV at the equilibrium state opening between the highest valence band and lowest conduction band located at the $$\varGamma $$ point. The band gap of the $$\hbox {C}_2\hbox {N}$$ nanosheet decreases with the increasing of both uniaxial/biaxial strains. In the presence of the strain, we found band shift and band splitting of the occupied and unoccupied energy states of the valence and conduction bands, resulting in a decrease of the band gap. Furthermore, the absorption and reflectance spectra for the $$\hbox {C}_2\hbox {N}$$ nanosheet have a broad peak around 2.6 eV, where a maximum absorption value is up to $$3.2 \times 10^{-5}\,\hbox {cm}^{-1}$$ and reflectance is about 0.27%. Moreover, our calculations also show that the optical properties of the $$\hbox {C}_2\hbox {N}$$ nanosheets can be controlled by applying the biaxial and uniaxial strains. The obtained results might provide potential applications for the $$\hbox {C}_2\hbox {N}$$ nanosheets in nanoelectronics and optoelectronics.