Electronic structure and optical properties of Y-doped, Yb-doped, and Y–Yb Co-doped AlN: a first-principles studyShiping Wang, Haixia Li and Jiacheng LiuEur. Phys. J. B, 99 6 (2026) 84DOI: https://doi.org/10.1140/epjb/s10051-026-01203-5