Eu 3+ ‐tetrakis β‐diketonate complexes for solid‐state lighting application

Eu 3+ –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 Eu 3+ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu 3+ tetrakis complexes based on [Q][Eu(tfaa) 4 ] and [Q][Eu(dbm) 4 ] (Q1 = C 26 H 56 N + , Q2 = C 19 H 42 N + , and Q3 = C 17 H 38 N + ), 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 Eu 3+ 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 Eu 3+ complexes, making it a potential candidate for SSL.