	US 12,484,440 B2
	Electroluminescent devices having sensitizer and fluorescent emitter
Ilona Stengel, Darmstadt (DE); Antonia Horn, Offenbach (DE); Falk May, Mainz (DE); Aaron Lackner, Mannheim (DE); Christof Pflumm, Darmstadt (DE); Amel Mekic, Darmstadt (DE); and Nils Haase, Darmstadt (DE)
Assigned to Merck Patent GmbH, Darmstadt (DE)
Appl. No. 17/276,060
Filed by Merck Patent GmbH, Darmstadt (DE)
PCT Filed Sep. 12, 2019, PCT No. PCT/EP2019/074290 § 371(c)(1), (2) Date Mar. 12, 2021, PCT Pub. No. WO2020/053314, PCT Pub. Date Mar. 19, 2020.
Claims priority of application No. 18194110 (EP), filed on Sep. 12, 2018.
Prior Publication US 2022/0045276 A1, Feb. 10, 2022
Int. Cl. H10K 85/60 (2023.01); H10K 85/30 (2023.01); H10K 50/11 (2023.01); H10K 50/12 (2023.01); H10K 101/10 (2023.01); H10K 101/30 (2023.01); H10K 101/40 (2023.01)

CPC H10K 85/623 (2023.02) [H10K 85/342 (2023.02); H10K 85/346 (2023.02); H10K 85/371 (2023.02); H10K 50/11 (2023.02); H10K 50/121 (2023.02); H10K 2101/10 (2023.02); H10K 2101/30 (2023.02); H10K 2101/40 (2023.02)]

21 Claims

1. A fluorescent electronic device comprising at least one layer, a sensitizer and a fluorescent emitter, wherein both the sensitizer and the fluorescent emitter are deposited by co-evaporation in the same one of at least one layer as a mixture, and wherein the sensitizer is a phosphorescent compound and wherein at least one of the two following conditions (I) or (II) must be satisfied:

S₁^K(FE)−S₁^K(S)≥X (I)

S₁^max(FE)−S₁^max(S)≤Y (II)

where the parameters used are as follows:

X, Y are each −0.5 eV or are each −0.4 eV,

S₁^K(FE) is an energy of a first excited singlet state of the fluorescent emitter which is ascertained from an edge of a first maximum on a short-wavelength side of a normalized photoluminescence spectrum of the fluorescent emitter;

S₁^K(S) is an energy of a first excited state of the sensitizer which is ascertained from an edge of a first maximum on a short-wavelength side of a normalized photoluminescence spectrum of the sensitizer;

S₁^max(FE) is the energy of the first excited singlet state of the fluorescent emitter which is ascertained from a location of the first maximum at short wavelengths of a photoluminescence spectrum of the fluorescent emitter;

S₁^max(S) is the energy of the first excited state of the sensitizer which is ascertained from a location of the first maximum at short wavelengths of a photoluminescence spectrum of the sensitizer;

wherein the photoluminescence spectra of the sensitizer and of the fluorescent emitter are determined from solution at a concentration of 1 mg in 100 ml of toluene at room temperature,

wherein the fluorescent emitter is a sterically shielded compound having a shielding factor (SF) of not less than 0.5;

wherein the photoluminescence emission spectrum of the sensitizer overlaps with an absorption spectrum of the fluorescent emitter; and

wherein the Forster radius is not more than 3 nm.