<p>With the aid of defect engineering, binary nitrides such as GaN and Mg₃N₂ have achieved significant advancements in the field of luminescence. However, studies on ternary nitrides, which offer more degrees of freedom for defect regulation, remain limited. The ternary compound Li₃AlN₂, derived from Mg₃N₂, has garnered some attention; however, its luminescence mechanism has not been thoroughly investigated. In this study, first-principles calculations based on the HSE06 hybrid functional were employed to explore the electronic structure, defect characteristics and defect-related optical transitions in Li₃AlN₂. Nitrogen vacancies, the primary intrinsic deep-level defects in the band gap, are identified as the main radiative centers, with the emission peaks obtained from the configuration coordinate diagram being in close agreement with the experimentally observed PL peaks. Among commonly used dopants in nitrides—including elements from Groups II, IV and VI—most are found to introduce very shallow defect levels. In contrast, carbon doping as well as rare-earth dopants Eu and Tb can introduce deep levels in the band gap, which are identified as potential contributors to luminescence. Our simulation results are consistent with experimental observations reported in the literature.</p> Graphical abstract <p>A systematic investigation into the defect-induced luminescence mechanism in the ternary nitride Li3AlN2 was conducted via fi rst-principles calculations. This investigation covered intrinsic defects, doping defects of elements from Groups II, IV, and VI, as well as common rare earth element doping.</p> <p> </p>