Abstract: | Eu3+–β‐diketonate complexes are used, for example, in solid‐state lighting (SSL) or light‐converting molecular devices. However, their low emission quantum efficiency due to water molecules coordinated to Eu3+ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu3+ tetrakis complexes based on Q]Eu(tfaa)4] and Q]Eu(dbm)4] (Q1 = C26H56N+, Q2 = C19H42N+, and Q3 = C17H38N+), replacing the water molecules in the tris stoichiometry. The tetrakis β‐diketonates showed desirable thermal stability for SSL and, under excitation at 390 nm, they displayed the characteristic Eu3+ emission in the red spectral region. The quantum efficiencies of the dbm complexes achieved values as high as 51%, while the tfaa complexes exhibited lower quantum efficiencies (28–33%), but which were superior to those reported for the tris complexes. The structures were evaluated using the Sparkle/PM7 model and comparing the theoretical and the experimental Judd–Ofelt parameters. Q1]Eu(dbm)4] was used to coat a near‐UV light‐emitting diode (LED), producing a red‐emitting LED prototype that featured the characteristic emission spectrum of Q1]Eu(dbm)4]. The emission intensity of this prototype decreased only 7% after 30 h, confirming its high photostability, which is a notable result considering Eu3+ complexes, making it a potential candidate for SSL. |