  Recently, a new type of two-dimensional layered material, i.e. C3N, has been
fabricated by polymerization of 2,3-diaminophenazine and used to fabricate a
field-effect transistor device with an on/off current ratio reaching 5.5E10
(Adv. Mater. 2017, 1605625). Here we have performed a comprehensive
first-principles study mechanical and electronic properties of C3N and related
derivatives. Ab inito molecular dynamics simulation shows that C3N monolayer
can withstand high temperature up to 2000K. Besides high stability, C3N is
predicted to be a superior stiff material with high Young's modulus (1090.0
GPa), which is comparable or even higher than that of graphene (1057.7 GPa). By
roll-up C3N nanosheet into the corresponding nanotube, an out-of-plane bending
deformation is also investigated. The calculation indicates C3N nanosheet
possesses a fascinating bending Poisson's effect, namely, bending induced
lateral contraction. Further investigation shows that most of the corresponding
nanotubes also present high Young's modulus and semiconducting properties. In
addition, the electronic properties of few-layer C3N nanosheet is also
investigated. It is predicated that C3N monolayer is an indirect semiconductor
(1.09 eV) with strongly polar covalent bonds, while the multi-layered C3N
possesses metallic properties with AD-stacking. Due to high stability, suitable
band gap and superior mechanical strength, the C3N nanosheet will be an ideal
candidate in high-strength nano-electronic device applications.
