The electronic and optical features of some potential single-photon sources in cubic boron nitride (c-BN) and two-dimensional silicon carbide monolayers (2D-SiC) are studied via ab-initio calculation. 9 defects in 2D-SiC and more than 30 defects in c-BN are considered. By applying performance criteria, Stone-Wales defects without and with combination of antisite defects in 2D-SiC and V B C B C N and V B SiV B in c-BN are studied in details. The formation energy calculations reveal that for Stone-Wales defects in 2D-SiC and V B C B C N defect in c-BN, positive and neutral charge states and for V B SiV B defect in c-BN, negative and neutral charge states are stabe. We compute the zero-phonon-line (ZPL) energy, the Huang-Rhys (HR) factor and the photoluminescence spectrum for the available transitions in the thier stable charge states. The calculated HR values and the related Debye-Waller factors guarantee that the Stone-Wales defects have a high potential of performing as a promising single-photon emitter. Also the obtained ZPL energy, HR factor and some other properties of V B C B C N and V B SiV B defects show that these defects can be related to the observed M1 and M2 centers in c-BN
