Design principles for achieving red emission in Eu²⁺/Eu³⁺ doped inorganic solids

Rare earth (RE) ions activated inorganic phosphors with multi-color emissions have received considerable attention because of their emerging applications in solid-state lighting, backlight displays, lasers, biomedical imaging, and so on. This tutorial review concerns the design principles for Eu2+ Eu3+ red-emitting solids highlights influencing factors on luminescence performance. Based recent advances structural RE phosphors, we proposed several achieving red emission Eu2+/Eu3+ doped materials. On one hand, realization from ion, used strategies include following: (1) designed synthesis new Eu2+-doped nitride or sulfide (2) anionic substitution achieves large centroid shift, (3) occupies polyhedrons small coordination numbers to obtain ?cfs, (4) doping concentration controls distribution ions, (5) mixed ligands induce ?S, (6) nitrides UCr4C4-type structure achieve narrow-band emission. other originating a are listed as follows: (i) Eu3+-doped CT energy, (ii) low excitation energy by sensitizer (iii) enhancement charge compensation, (iv) occupation unsymmetrical sites maintain high color purity Eu3+. Finally, discuss look at future opportunities phosphors.