Mechanical behaviors and electronic characteristics on two-dimensional C2N3 and C2N3H: First principles calculations

Opening its band gap has become an important task since the discovery of graphene in 2004. Recently, two-dimensional (2D) carbon nitride with a composition near C2N3 was successfully synthesized. C2N3 has attracted much attention because of its semiconductor behavior. In this study, mechanical behaviors and electronic characteristics of C2N3 and C2N3H are investigated by first principles calculations. The results reveal that C2N3 and C2N3H are very soft 2D materials. C2N3 exhibits a heavily doped p-type semiconductor characteristic, while C2N3H shows an intrinsic semiconductor behavior with the HSE06 band gap changing from 4.62 eV to 3.92 eV. Molecular dynamics simulation shows that monolayer C2N3 and C2N3H at 300 K can sustain the biaxial strain levels of ɛ = 9% and ɛ = 13%. The C2N3 breaks first from C3N3 rings as the strain is further increased, while the C2N3H breaks first from the − NH− linking. It is found that interlayer voids in C2N3H occupied by O, Na, Mg, S, Si, K, Ca, Cl, Br, or I atoms can increase the interface cohesive energy and enhance structural stability. These interstitial atoms introduce transition levels and fixed charges into the band gap, thus affecting the transport properties of C2N3H.