First-Principles calculations are carried out to explore two newly designed selenates \([SrSe{O}_{4}]:{Eu}^{2+}\) and \([SrSe{O}_{4}]:{Tb}^{2+}\) in terms of their structural, magnetic, optical, and electronic properties mainly based on density functional theory (DFT). The investigated materials are found to have direct band gap values of 1.53 and 3.02 eV, respectively for spin up configuration whereas 1.54 and 3.04 eV for spin down configurations. The density of states plots in spin up and spin down configurations show substantial differences that indicate the reasonable magnetic moments. Further, the optical parameters show that there are strong absorption peaks in ultraviolet (UV) region and the reflectivity peaks reveals the applications like anti-reflective coatings. Therefore, the studied compounds \([SrSe{O}_{4}]:{Eu}^{2+}\) , and \([SrSe{O}_{4}]:{Tb}^{2+}\) are very promising for optoelectronic applications in UV region.
