Charge transfer from Eu²⁺ to trivalent lanthanide co-dopants: Systematic behavior across the series

Electron transfer processes between lanthanide activators are crucial for the functional behavior and performance of luminescent materials. Here, a multiconfigurational ab initio study reveals how direct metal-to-metal charge (MMCT) Eu2+ luminescence activator Ln3+ co-dopant (Ln3+ = Ce3+, Pr3+, Nd3+, Pm3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) systematically dictates optical properties CaF2. The combination structures energies electronic manifolds, vibrational force constants, structural donor acceptor in host determines predictions five different behaviors CaF2:Eu2+, co-doped materials after MMCT absorption: formation stable traps, emission, emission quenching, emission.