  Searching the novel 2D semiconductor is crucial to develop the
next-generation low-dimensional electronic device. Using first-principles
calculations, we propose a class of unexplored binary V-V compound
semiconductor (PN, AsN, SbN, AsP, SbP and SbAs) with monolayer black
phosphorene ($\alpha$) and blue phosphorene ($\beta$) structure. Our phonon
spectra and room-temperature molecular dynamics (MD) calculations indicate that
all compounds are very stable. Moreover, most of compounds are found to present
a moderate energy gap in the visible frequency range, which can be tuned
gradually by in-plane strain. Especially, $\alpha$-phase V-V compounds have a
direct gap while $\beta$-SbN, AsN, SbP, and SbAs may be promising candidates of
2D solar cell materials due to a wide gap separating acoustic and optical
phonon modes. Furthermore, vertical heterostructures can be also built using
lattice matched $\alpha$($\beta$)-SbN and phosphorene, and both vdW
heterostructures are found to have intriguing direct band gap. The present
investigation not only broads the scope of layered group V semiconductors but
also provides an unprecedented route for the potential applications of 2D V-V
families in optoelectronic and nanoelectronic semiconductor devices.
