Single-photon sources (SPS) based on solid-state point defects are significant for advancing quantum technologies. Two-dimensional (2D) semiconductor materials with open structure offer advantages such as high photon extraction efficiency and the ability to integrate with photonic circuits. Recently, two-dimensional silicon carbide (2D-SiC) has emerged as a potential host material for SPS. In this study, first-principles calculations predict and identify two kinds of intrinsic point defects ${\mathrm{V}}_{\mathrm{Si}}{\mathrm{V}}_{\mathrm{C}}$ and ${\mathrm{V}}_{\mathrm{Si}}\mathrm{S}{\mathrm{i}}_{\mathrm{C}}$ in 2D-SiC, which stabilities were confirmed through defect formation energies and binding energies. Among the 18 identified transition pathways, two pathways $a_1\to b_1^{\left(1\right)}$ and $a_1\to b_1^{\left(2\right)}$ in the ${\mathrm{V}}_{\mathrm{Si}}{\mathrm{V}}_{\mathrm{C}}^{-}$ defect were selected based on their transition dipole moment and $\mathrm{\Delta }Q$ values, as they represent allowed optical transitions with superior optical properties. The results indicate that the pathway $a_1\to b_1^{\left(2\right)}$ exhibits the smaller Huang-Rhys factor of 1.474 and the larger Debye-Waller factor of 22.90%, and a short radiative lifetime of 3.4 ns. Additionally, the hyperfine tensor of the ${\mathrm{V}}_{\mathrm{Si}}{\mathrm{V}}_{\mathrm{C}}^{-}$ defect was calculated to facilitate the identification of defect centers. Our findings indicate that the ${\mathrm{V}}_{\mathrm{Si}}{\mathrm{V}}_{\mathrm{C}}^{-}$ defect in 2D-SiC is a potential candidate for SPS.

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• Defects
• Electrical properties
• First-principles calculations
• Luminescence