In the present study, we investigate the structural, electronic, and optical properties of pure and doped boron-nitride (BN) nano-systems using density functional theory (DFT) simulations. Metal dopant C, Ni and Cu were introduced. Structural properties, such as bond length and formation energy, were observed, and the bond lengths were found to agree with experimental results previously reported in the literature. The metal atoms in the metal-doped BN nanosystem were shown to have a direct effect on the nature of the surface. The calculated formation energies show that the stability of the BN nanosystem is enhanced upon metallic doping, as clearly shown in the case of Ni-doped boron nitride (NiBN). The metal dopant is found to reduce the energy gap and enhance overall electrical conductivity. UV-Visible spectrum calculations show that the metal atom causes a red-shift in the spectrum towards the red wavelengths. Open-circuit voltage (VOC) calculation shows that Ni-doping of BN enhances the VOC by 420 meV with respect to pristine BN, thereby confirming the positive impact of the dopant Ni on the twodimensional h-BN surface and consequent possible usefulness in optoelectronics.