  We model bilayer graphene-like materials with Si$_2$C$_{14}$ and BC$_{14}$N
stoichiometry, where the interlayer interactions play important roles shaping
the physical properties of the systems. We find the interlayer interaction in
Si$_2$C$_{14}$ to be repulsive due to the interaction of Si-Si atoms, and in
BC$_{14}$N it is attractive due to B and N atoms for both the AA- and the
AB-stacking. The repulsive interlayer interaction opens up a bandgap in
Si$_2$C$_{14}$ while the attractive interlayer interaction in BC$_{14}$N
induces a small indirect bandgap or overlaping of the valence conduction bands.
Furthermore, the repulsive interaction decreases the Young modulus while the
attractive interaction does not influence the Young modulus much. The
stress-strain curves of both the AA- and the AB-stackings are suppressed
compared to pure graphine bilayers. The optical response of Si$_2$C$_{14}$ is
very sensitive to an applied electric field and an enrichment in the optical
spectra is found at low energy. The enrichment is attributed to the bandgap
opening and increased energy spacing between the $\pi{\text -}\pi^*$ bands. In
BC$_{14}$N, the optical spectra are reduced due to the indirect bandgap or the
overlapping of the $\pi{\text -}\pi^* $ bands. Last, a high Seebeck coefficient
is observed due to the presence of a direct bandgap in Si$_2$C$_{14}$, while it
is not much enhanced in BC$_{14}$N.
