Potential ultraviolet luminescence in 2D Bi2SeO5: First-principles insights into its luminescent mechanism

Abstract

Nitride ultraviolet (UV) LEDs suffer from low efficiency due to high defect densities, p-type doping challenges, and poor carrier mobility. Overcoming these limitations requires defect passivation and interface optimization, which remain major technical hurdles. Consequently, identifying new wide-bandgap material for efficient UV-emitting devices is essential. In this paper, first-principles calculations have been performed to investigate the potential UV luminescence of 2D wide-bandgap Bi2SeO5. The results indicate that BiSe, SeBi, and VO with low formation energies can act as the possible luminescent defects. Charge state analysis reveals BiSe−, VO2+, and SeBi+ are the most stable charge states, serving as the ground state luminescence centers. The transition levels of BiSe (0/−), SeBi (0/+), VO (+/2+), and VBi (2−/3−) within the bandgap function as potential hole or electron capture centers. Notably, BiSe1− and SeBi2+ alternately dominate the defect landscape at the highest concentration, thereby significantly enhancing luminescence intensity and efficiency. Under excitation near 3.7 eV, both BiSe1− and SeBi2+ give rise to a UV photoluminescence peak at 3.48 eV. These insights demonstrate that Bi2SeO5 possesses strong potential as an UV luminescent material and establish a theoretical foundation for its applications in UV-emitting devices.