ORGANIC ELECTROLUMINESCENT DEVICE EMITTING VISIBLE LIGHT

Abstract

The invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising a host material H.sup.B, a thermally activated delayed fluorescence (TADF) material E.sup.B, and a depopulation agent S.sup.B.

Claims

1-16. (canceled)

17. An organic electroluminescent device comprising a light-emitting layer B comprising: (i) a host material H.sup.B, which has a lowermost excited singlet state energy level S1.sup.H, a lowermost excited triplet state energy level T1.sup.H, and a highest occupied molecular orbital HOMO(H.sup.B) having an energy E.sup.HOMO(H.sup.B); (ii) a thermally activated delayed fluorescence (TADF) material E.sup.B, which has a lowermost excited singlet state energy level S1.sup.E, a lowermost excited triplet state energy level T1.sup.E, and a highest occupied molecular orbital HOMO(E.sup.B) having an energy E.sup.HOMO(E.sup.B); and (iii) a depopulation agent S.sup.B, which has a lowermost excited singlet state energy level S1.sup.S, optionally a lowermost excited triplet state energy level T1.sup.S, and a highest occupied molecular orbital HOMO(S.sup.B) having an energy E.sup.HOMO(S.sup.B); wherein E.sup.B emits thermally activated delayed fluorescence; and wherein the relations expressed by the following formulas (1) to (3) and either (4a) and (4b), or (5a) and (5b) apply:
S1.sup.H>S1.sup.E (1)
S1.sup.H>S1.sup.S (2)
S1.sup.S>S1.sup.E (3)
E.sup.HOMO(E.sup.B)≤E.sup.HOMO(H.sup.B) (4a)
0.2 eV≤E.sup.HOMO(S.sup.B)−E.sup.HOMO(E.sup.B)≤0.8 eV (4b)
E.sup.HOMO(H.sup.B)≥E.sup.HOMO(E.sup.B) (5a)
0.2 eV≤E.sup.HOMO(S.sup.B)−E.sup.HOMO(H.sup.B)≤0.8 eV (5b).

18. The organic electroluminescent device according to claim 17, wherein the TADF material E.sup.B has a ΔE.sub.ST value, which corresponds to the energy difference between S1.sup.E and T1.sup.E, of less than 0.4 eV.

19. The organic electroluminescent device according to claim 17, wherein the mass ratio of the TADF material E.sup.B to depopulation agent S.sup.B (E.sup.B:S.sup.B) is >1.

20. The organic electroluminescent device according to claim 17, wherein the organic electroluminescent device is selected from the group consisting of an organic light emitting diode, a light emitting electrochemical cell, and a light-emitting transistor.

21. The organic electroluminescent device according to claim 17, wherein the TADF material E.sup.B is an organic TADF emitter or a combination of two or more organic TADF emitters.

22. The organic electroluminescent device according to claim 17, wherein the depopulation agent S.sup.B is an organic TADF emitter or a combination of two or more organic TADF emitters.

23. The organic electroluminescent device according to claim 17, wherein the relation between the lowest unoccupied molecular orbital LUMO(E.sup.B) of the TADF material E.sup.B having an energy E.sub.LUMO(E.sup.B) and the lowest unoccupied molecular orbital LUMO(S.sup.B) of the depopulation agent S.sup.B having an energy E.sup.LUMO(S.sup.B) expressed by formula (7) applies:
E.sup.LUMO(S.sup.B)>E.sup.LUMO(E.sup.B) (7).

24. The organic electroluminescent device according to claim 17, wherein a relation expressed by formula (6a), (6b), or (6c) applies:
E.sup.HOMO(E.sup.B)>E.sup.HOMO(H.sup.B) (6a)
E.sup.HOMO(H.sup.B)>E.sup.HOMO(E.sup.B) (6b)
−0.2 eV≤E.sup.HOMO(H.sup.B)−E.sup.HOMO(E.sup.B)≤0.2 eV (6c).

25. The organic electroluminescent device according to claim 17, wherein the light-emitting layer B comprises: (i) 39.8-98% by weight of the host compound H.sup.B; (ii) 0.1-50% by weight of the TADF material E.sup.B; and (iii) 0.1-50% by weight of depopulation agent S.sup.B; and optionally (iv) 0-60% by weight of one or more further host compounds H.sup.B2 differing from H.sup.B; and optionally (v) 0-60% by weight of one or more solvents; and optionally (vi) 0-30% by weight of at least one further emitter molecule F.

26. The organic electroluminescent device according to claim 17, wherein the light-emitting layer B comprises 1-8% by weight of the depopulation agent S.sup.B.

27. The organic electroluminescent device according to claim 17, wherein the depopulation agent S.sup.B has a ΔE.sub.ST value, which corresponds to the energy difference between S1.sup.S and T1.sup.S, of less than 0.4 eV.

28. The organic electroluminescent device according to claim 17, wherein the TADF emitter E.sup.B and/or the depopulation agent S.sup.B comprises or consists of a structure according to Formula I-TADF ##STR00115## wherein: is at each occurrence independently from another 1 or 2; p is at each occurrence independently from another 1 or 2; X is at each occurrence independently from another selected from the group consisting of Ar.sup.EWGH, CN, and CF.sub.3; Z is at each occurrence independently from another selected from the group consisting of a direct bond, CR.sup.3R.sup.4, C═CR.sup.3R.sup.4, C═O, C═NR.sup.3, NR.sup.3, O, SiR.sup.3R.sup.4, S, S(O), and S(O).sub.2; Ar.sup.EWG is at each occurrence independently from another a structure according to one of Formulas IIa to IIk ##STR00116## ##STR00117## wherein # represents the binding site of the single bond linking Ar.sup.EWG to the substituted central phenyl ring of Formula I-TADF; R.sup.1 is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, C.sub.1-C.sub.5-alkyl, wherein one or more hydrogen atoms are optionally substituted by deuterium, and C.sub.6-C.sub.18-aryl, which is optionally substituted with one or more substituents R.sup.6; R.sup.2 is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, C.sub.1-C.sub.5-alkyl, wherein one or more hydrogen atoms are optionally substituted by deuterium, and C.sub.6-C.sub.18-aryl, which is optionally substituted with one or more substituents R.sup.6; R.sup.a, R.sup.3, and R.sup.4 are at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, N(R.sup.5).sub.2, OR.sup.5, SR.sub.5, Si(R.sup.5).sub.3, CF.sub.3, CN, F, C.sub.1-C.sub.40-alkyl, which is optionally substituted with one or more substituents R.sup.5 and wherein one or more non-adjacent CH.sub.2-groups are optionally substituted by R.sup.5C═CR.sup.5, C≡C, Si(R.sup.5).sub.2, Ge(R.sup.5).sub.2, Sn(R.sup.5).sub.2, C═O, C═S, C═Se, C═NR.sup.5, P(═O)(R.sup.5), SO, SO.sub.2, NR.sup.5, O, S, or CONR.sup.5; C.sub.1-C.sub.40-thioalkoxy, which is optionally substituted with one or more substituents R.sup.5 and wherein one or more non-adjacent CH.sub.2-groups are optionally substituted by R.sup.5C═CR.sup.5, C≡C, Si(R.sup.5).sub.2, Ge(R.sup.5).sub.2, Sn(R.sup.5).sub.2, C═O, C═S, C═Se, C═NR.sup.5, P(═O)(R.sup.5), SO, SO.sub.2, NR.sup.5, O, S, or CONR.sup.5; C.sub.6-C.sub.60-aryl, which is optionally substituted with one or more substituents R.sup.5; and C.sub.3-C.sub.57-heteroaryl, which is optionally substituted with one or more substituents R.sup.5; R.sup.5 is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, N(R.sup.6).sub.2, OR.sup.6, SR.sup.6, Si(R.sup.6).sub.3, CF.sub.3, CN, F, C.sub.1-C.sub.40-alkyl, which is optionally substituted with one or more substituents R.sup.6 and wherein one or more non-adjacent CH.sub.2-groups are optionally substituted by R.sup.6C═CR.sup.6, C≡C, Si(R.sup.6).sub.2, Ge(R.sup.6).sub.2, Sn(R.sup.6).sub.2, C═O, C═S, C═Se, C═NR.sup.6, P(═O)(R.sup.6), SO, SO.sub.2, NR.sup.6, O, S, or CONR.sup.6; C.sub.6-C.sub.60-aryl, which is optionally substituted with one or more substituents R.sup.6; and C.sub.3-C.sub.57-heteroaryl, which is optionally substituted with one or more substituents R.sup.6; R.sup.6 is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, OPh, CF.sub.3, CN, F, C.sub.1-C.sub.5-alkyl, wherein one or more hydrogen atoms are optionally, independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-alkoxy, wherein one or more hydrogen atoms are optionally, independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-thioalkoxy, wherein one or more hydrogen atoms are optionally, independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.6-C.sub.18-aryl, which is optionally substituted with one or more C.sub.1-C.sub.5-alkyl substituents; C.sub.3-C.sub.17-heteroaryl, which is optionally substituted with one or more C.sub.6-C.sub.18-aryl substituents and/or one or more C.sub.1-C.sub.5-alkyl substituents; N(C.sub.6-C.sub.18-aryl).sub.2; N(C.sub.3-C.sub.17-heteroaryl).sub.2; and N(C.sub.3-C.sub.17-heteroaryl)(C.sub.6-C.sub.18-aryl); R.sup.d is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, N(R.sup.5).sub.2, OR.sup.5, SR.sup.5, Si(R.sup.5).sub.3, CF.sub.3, CN, F, C.sub.1-C.sub.40-alkyl, which is optionally substituted with one or more substituents R.sup.5 and wherein one or more non-adjacent CH.sub.2-groups are optionally substituted by R.sup.5C═CR.sup.5, C≡C, Si(R.sup.5).sub.2, Ge(R.sup.5).sub.2, Sn(R.sup.5).sub.2, C═O, C═S, C═Se, C═NR.sup.5, P(═O)(R.sup.5), SO, SO.sub.2, NR.sup.5, O, S, or CONR.sup.5; C.sub.1-C.sub.40-thioalkoxy, which is optionally substituted with one or more substituents R.sup.5 and wherein one or more non-adjacent CH.sub.2-groups are optionally substituted by R.sup.5C═CR.sup.5, C≡C, Si(R.sup.5).sub.2, Ge(R.sup.5).sub.2, Sn(R.sup.5).sub.2, C═O, C═S, C═Se, C═NR.sup.5, P(═O)(R.sup.5), SO, SO.sub.2, NR.sup.5, O, S, or CONR.sup.5; C.sub.6-C.sub.60-aryl, which is optionally substituted with one or more substituents R.sup.5; and C.sub.3-C.sub.57-heteroaryl which is optionally substituted with one or more substituents R.sup.5; wherein the substituents R.sup.a, R.sup.3, R.sup.4, or R.sup.5 independently from each other may optionally form a mono- or polycyclic, aliphatic, aromatic, and/or benzo-fused ring system with one or more other substituents R.sup.a, R.sup.3, R.sup.4, or R.sup.5; and wherein the one or more substituents R.sup.d independently from each other may optionally form a mono- or polycyclic, aliphatic, aromatic, and/or benzo-fused ring system with one or more other substituents R.sup.d.

29. The organic electroluminescent device according to claim 17, wherein depopulation agent S.sup.B comprises or consists of a structure according to Formula I-NRCT: ##STR00118## wherein: o is 0 or 1; m=1−o; X.sup.1 is N or B; X.sup.2 is N or B; X.sup.3 is N or B; W is selected from the group consisting of Si(R.sup.3S).sub.2, C(R.sup.3S).sub.2, and BR.sup.3S; each of R.sup.1S, R.sup.2S, and R.sup.3S is independently from each other selected from the group consisting of: C.sub.1-C.sub.5-alkyl, which is optionally substituted with one or more substituents R.sup.6S; C.sub.6-C.sub.60-aryl, which is optionally substituted with one or more substituents R.sup.6S; and C.sub.3-C.sub.57-heteroaryl, which is optionally substituted with one or more substituents R.sup.6S; each of R.sup.I, R.sup.II, R.sup.III, R.sup.IV, R.sup.V, R.sup.VI, R.sup.VII, R.sup.VIII, R.sup.IX, R.sup.X, and R.sup.XI is independently from another selected from the group consisting of: hydrogen, deuterium, N(R.sup.5S).sub.2, OR.sup.5S, Si(R.sup.5S).sub.3, B(OR.sup.5S).sub.2, OSO.sub.2R.sup.5S, CF.sub.3, CN, halogen, C.sub.1-C.sub.40-alkyl, which is optionally substituted with one or more substituents R.sup.5S, and wherein one or more non-adjacent CH.sub.2-groups are each optionally substituted by R.sup.55C═CR.sup.5S, C≡C, Si(R.sup.5S).sub.2, Ge(R.sup.5S).sub.2, Sn(R.sup.5S).sub.2, C═O, C═S, C═Se, C═NR.sup.5S, P(═O)(R.sup.5S), SO, SO.sub.2, NR.sup.5S, O, S, or CONR.sup.5S; C.sub.1-C.sub.40-alkoxy, which is optionally substituted with one or more substituents R.sup.5S, and wherein one or more non-adjacent CH.sub.2-groups are each optionally substituted by R.sup.5SC═CR.sup.5S, C≡C, Si(R.sup.5S).sub.2, Ge(R.sup.5S).sub.2, Sn(R.sup.5S).sub.2, C═O, C═S, C═Se, C═NR.sup.5S, P(═O)(R.sup.5S), SO, SO.sub.2, NR.sup.5S, O, S, or CONR.sup.5S; C.sub.1-C.sub.40-thioalkoxy, which is optionally substituted with one or more substituents R.sup.5S, and wherein one or more non-adjacent CH.sub.2-groups are each optionally substituted by R.sup.5SC═CR.sup.5S, C≡C, Si(R.sup.5S).sub.2, Ge(R.sup.5S).sub.2, Sn(R.sup.5S).sub.2, C═O, C═S, C═Se, C═NR.sup.5S, P(═O)(R.sup.5S), SO, SO.sub.2, NR.sup.5S, O, S, or CONR.sup.5S; C.sub.2-C.sub.40-alkenyl, which is optionally substituted with one or more substituents R.sup.5S, and wherein one or more non-adjacent CH.sub.2-groups are each optionally substituted by R.sup.5SC═CR.sup.5S, C≡C, Si(R.sup.5S).sub.2, Ge(R.sup.5S).sub.2, Sn(R.sup.5S).sub.2, C═O, C═S, C═Se, C═NR.sup.5S, P(═O)(R.sup.5S), SO, SO.sub.2, NR.sup.5S, O, S, or CONR.sup.5S; C.sub.2-C.sub.40-alkynyl, which is optionally substituted with one or more substituents R.sup.5S, and wherein one or more non-adjacent CH.sub.2-groups are each optionally substituted by R.sup.5SC═CR.sup.5S, C≡C, Si(R.sup.5S).sub.2, Ge(R.sup.5S).sub.2, Sn(R.sup.5S).sub.2, C═O, C═S, C═Se, C═NR.sup.5S, P(═O)(R.sup.5S), SO, SO.sub.2, NR.sup.5S, O, S, or CONR.sup.5S; C.sub.6-C.sub.60-aryl, which is optionally substituted with one or more substituents R.sup.5S; and C.sub.3-C.sub.57-heteroaryl, which is optionally substituted with one or more substituents RSS; R.sup.5S is at each occurrence independently from another selected from the group consisting of: hydrogen, deuterium, OPh, CF.sub.3, CN, F, C.sub.1-C.sub.5-alkyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-alkoxy, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-thioalkoxy, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.2-C.sub.5-alkenyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.2-C.sub.5-alkynyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.6-C.sub.18-aryl, which is optionally substituted with one or more C.sub.1-C.sub.5-alkyl substituents; C.sub.3-C.sub.17-heteroaryl, which is optionally substituted with one or more C.sub.1-C.sub.5-alkyl substituents; N(C.sub.6-C.sub.18-aryl).sub.2; N(C.sub.3-C.sub.17-heteroaryl).sub.2; and N(C.sub.3-C.sub.17-heteroaryl)(C.sub.6-C.sub.18-aryl); R.sup.6S is at each occurrence independently from another selected from the group consisting of hydrogen, deuterium, OPh, CF.sub.3, CN, F, C.sub.1-C.sub.5-alkyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-alkoxy, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.1-C.sub.5-thioalkoxy, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.2-C.sub.5-alkenyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.2-C.sub.5-alkynyl, wherein optionally one or more hydrogen atoms are independently from each other substituted by deuterium, CN, CF.sub.3, or F; C.sub.6-C.sub.18-aryl, which is optionally substituted with one or more C.sub.1-C.sub.5-alkyl substituents; C.sub.3-C.sub.17-heteroaryl, which is optionally substituted with one or more C.sub.1-C.sub.5-alkyl substituents; N(C.sub.6-C.sub.15-aryl).sub.2; N(C.sub.3-C.sub.17-heteroaryl).sub.2; and N(C.sub.3-C.sub.17-heteroaryl)(C.sub.6-C.sub.15-aryl); wherein two or more of the substituents selected from the group consisting of R.sup.I, R.sup.II, R.sup.III, R.sup.IV, R.sup.V, R.sup.VI, R.sup.VII, R.sup.VIII, R.sup.IX, R.sup.X, and R.sup.XI that are positioned adjacent to another may optionally each form a mono- or polycyclic, aliphatic, aromatic, and/or benzo-fused ring system with another; and wherein at least one of X.sup.1, X.sup.2, and X.sup.3 is B and at least one of X.sup.1, X.sup.2, and X.sup.3 is N.

30. A method for generating visible light comprising the steps of: (i) providing an organic electroluminescent device according to claim 17; and (ii) applying an electrical current to the organic electroluminescent device.

31. A thermally activated delayed fluorescence (TADF) material E.sup.B in combination with at least one host material H.sup.B and at least one depopulation agent S.sup.B in a light-emitting layer for increasing the lifetime of the organic electroluminescent device.

32. The TADF material E.sup.B in combination with at least one host material H.sup.B and at least one depopulation agent S.sup.B in a light-emitting layer of claim 31, wherein: (i) the host material H.sup.B has a lowermost excited singlet state energy level S1.sup.H, a lowermost excited triplet state energy level T1.sup.H, and a highest occupied molecular orbital HOMO(H.sup.B) having an energy E.sup.HOMO(H.sup.B); (ii) the TADF material E.sup.B has a lowermost excited singlet state energy level S1.sup.E, a lowermost excited triplet state energy level T1.sup.E, and a highest occupied molecular orbital HOMO(E.sup.B) having an energy E.sup.HOMO(E.sup.B); and (iii) the depopulation agent S.sup.B has a lowermost excited singlet state energy level S1.sup.S, optionally a lowermost excited triplet state energy level T1.sup.S, and a highest occupied molecular orbital HOMO(S.sup.B) having an energy E.sup.HOMO(S.sup.B); wherein E.sup.B emits thermally activated delayed fluorescence; and wherein the relations expressed by the following formulas (1) to (3) and either (4a) and (4b), or (5a) and (5b) apply:
S1.sup.H>S1.sup.E (1)
S1.sup.H>S1.sup.S (2)
S1.sup.S>S1.sup.E (3)
E.sup.HOMO(E.sup.B)≤E.sup.HOMO(H.sup.B) (4a)
0.2 eV≤E.sup.HOMO(S.sup.B)−E.sup.HOMO(E.sup.B)≤0.8 eV (4b)
E.sup.HOMO(H.sup.B)≥E.sup.HOMO(E.sup.B) (5a)
0.2 eV≤E.sup.HOMO(S.sup.B)−E.sup.HOMO(H.sup.B)≤0.8 eV (5b).

Description

EXAMPLES

Cyclic Voltammetry

[0290] Cyclic voltammograms of solutions having concentration of 10-3 mol/l of the organic molecules in dichloromethane or a suitable solvent and a suitable supporting electrolyte (e.g. 0.1 mol/l of tetrabutylammonium hexafluorophosphate) are measured. The measurements are conducted at room temperature and under nitrogen atmosphere with a three-electrode assembly (Working and counter electrodes: Pt wire, reference electrode: Pt wire) and calibrated using FeCp.sub.2/FeCp.sub.2.sup.+ as internal standard. HOMO data was corrected using ferrocene as internal standard against SCE.

Density Functional Theory Calculation

[0291] Molecular structures are optimized employing the BP86 functional and the resolution of identity approach (RI). Excitation energies are calculated using the (BP86) optimized structures employing Time-Dependent DFT (TD-DFT) methods. Orbital and excited state energies are calculated with the B3LYP functional. Def2-SVP basis sets (and a m4-grid for numerical integration were used. The Turbomole program package was used for all calculations.

Photophysical Measurements

[0292] Sample Preparation of host material and organic TADF emitters:

Stock solution 1: 10 mg of sample (organic TADF material or host material) is dissolved in 1 ml of solvent.
Stock solution 2: 10 mg of PMMA is dissolved in 1 ml solvent.

[0293] The solvent is typically selected from toluene, chlorobenzene, dichloromethane and chloroform.

[0294] An Eppendorf pipette is used to add 1 ml of stock solution 1 to 9 ml of stock solution 2 to achieve a 10% by weight of sample in PMMA.

[0295] Alternatively, the photophysical properties of host material can be characterized in neat films of host material.

[0296] Sample Preparation of fluorescence emitters and NRCT emitters:

Stock solution 1: 10 mg of sample (fluorescence emitters and NRCT emitters) is dissolved in 1 ml of solvent.
Stock solution 1a: 9 ml of solvent is added to 1 ml of stock solution 1.
Stock solution 2: 10 mg of PMMA is dissolved in 1 ml solvent.

[0297] The solvent is typically selected from toluene, chlorobenzene, dichloromethane and chloroform.

[0298] An Eppendorf pipette is used to add 1 ml of stock solution 1 to 9.9 ml of stock solution 2 to achieve a 1% by weight of sample in PMMA.

[0299] Alternatively, the photophysical properties of fluorescence emitters can be characterized in solution, wherein a concentration of 0.001 mg/ml of fluorescence emitter in solution is used.

Sample Pretreatment: Spin-Coating

[0300] Apparatus: Spin150, SPS euro.
Program: 1) 3 s at 400 U/min; 20 s at 1000 U/min at 1000 Upm/s. 3) 10 s at 4000 U/min at 1000 Upm/s. After coating, the films are dried at 70° C. for 1 min.

Photoluminescence Spectroscopy and TCSPC (Time-Correlated Single-Photon Counting)

[0301] Steady-state emission spectroscopy is recorded using a Horiba Scientific, Modell FluoroMax-4 equipped with a 150 W Xenon-Arc lamp, excitation- and emissions monochromators and a Hamamatsu R928 photomultiplier and a time-correlated single-photon counting option. Emissions and excitation spectra are corrected using standard correction fits.

[0302] Excited state lifetimes are determined employing the same system using the TCSPC method with FM-2013 equipment and a Horiba Yvon TCSPC hub.

Excitation Sources:

[0303] NanoLED 370 (wavelength: 371 nm, puls duration: 1.1 ns)
NanoLED 290 (wavelength: 294 nm, puls duration: <1 ns)
SpectraLED 310 (wavelength: 314 nm)
SpectraLED 355 (wavelength: 355 nm).

[0304] Data analysis (exponential fit) was done using the software suite DataStation and DAS6 analysis software. The fit is specified using the chi-squared-test.

Photoluminescence Quantum Yield Measurements

[0305] For photoluminescence quantum yield (PLQY) measurements an Absolute PL Quantum Yield Measurement C9920-03G system (Hamamatsu Photonics) is used. Quantum yields and CIE coordinates were determined using the software U6039-05 version 3.6.0.

[0306] Emission maxima are given in nm, quantum yields CD in % and CIE coordinates as x,y values.

[0307] PLQY was determined using the following protocol: [0308] 1) Quality assurance: Anthracene in ethanol (known concentration) is used as reference [0309] 2) Excitation wavelength: the absorption maximum of the organic molecule is determined and the molecule is excited using this wavelength [0310] 3) Measurement [0311] Quantum yields are measured for sample of solutions or films under nitrogen atmosphere. The yield is calculated using the equation:

[00001] $Φ_{P L} = \frac{n_{photon}, emited}{n_{photon}, absorbed} = \frac{\int \frac{λ}{h c} [{Int}_{emitted}^{sample} (λ) - {Int}_{absorbed}^{sample} (λ)] d λ}{\int \frac{λ}{h c} [{Int}_{emitted}^{reference} (λ) - {Int}_{absorbed}^{reference} (λ)] d λ}$ [0312] wherein n.sub.photon denotes the photon count and Int. is the intensity.

Production and Characterization of Organic Electroluminescence Devices

[0313] Via vacuum-deposition methods OLED devices comprising organic molecules according to the invention can be produced. If a layer contains more than one compound, the weight-percentage of one or more compounds is given in %. The total weight-percentage values amount to 100%, thus if a value is not given, the fraction of this compound equals to the difference between the given values and 100%.

[0314] The not fully optimized OLEDs are characterized using standard methods and measuring electroluminescence spectra, the external quantum efficiency (in %) in dependency on the intensity, calculated using the light detected by the photodiode, and the current. The OLED device lifetime is extracted from the change of the luminance during operation at constant current density, which is given in mA/cm.sup.2. The LT50 value corresponds to the time, where the measured luminance decreased to 50% of the initial luminance, analogously LT80 corresponds to the time point, at which the measured luminance decreased to 80% of the initial luminance, LT97 to the time point, at which the measured luminance decreased to 97% of the initial luminance etc.

[0315] Accelerated lifetime measurements are performed (e.g. applying increased current densities). Exemplarily LT95 values at 1200 cd/m.sup.2 are determined using the following equation:

[00002] $L T 95 (1200 \frac{cd}{m^{2}}) = L T 9 5 (L_{0}) {(\frac{L_{0}}{1200 \frac{cd}{m^{2}}})}^{1.6}$

wherein L.sub.0 denotes the initial luminance at the applied current density.

[0316] The values correspond to the average of several pixels (typically two to eight), the standard deviation between these pixels is given. The results show the data series for one OLED pixel.

Comparative Examples C1 and Examples E1 to E7

[0317] ##STR00111## ##STR00112## ##STR00113## ##STR00114##

Depopulation Agent 7

[0318]

TABLE-US-00001 TABLE 1 Physicochemical properties of the materials Material E.sup.HOMO [eV] E.sup.LUMO [eV] S1 [eV] T1 [eV] mCBP (H.sup.B) −6.02 −2.42 3.60 2.82 TADF1 (E.sup.B) −5.99 −3.35 2.64 2.65 Depopulation Agent 1 −5.48 −2.73 2.75 2.59 (S.sup.B) Depopulation Agent 2 −5.54 −2.20 3.34 2.9 (S.sup.B) Depopulation Agent 3 −5.55 −2.69 2.86 (S.sup.B) Depopulation Agent 4 −5.72 −2.95 2.77 2.60 (S.sup.B) Depopulation Agent 5 −5.66 −2.35 3.31 2.71 (S.sup.B) Depopulation Agent 6 −5.66 −2.70 2.96 (S.sup.B) Depopulation Agent 7 −5.86 −2.88 2.98 2.62 (S.sup.B)

TABLE-US-00002 TABLE 2 Examples of setups of devices D1 to D7 Comparative Layer Thickness Examples (Ex.) Example C1 10 100 nm Al Al 9 2 nm Liq Liq 8 20 nm NBPhen NBPhen 7 10 nm HBL1 HBL1 6 50 nm Depopulation Agent selected from TADF1 (20%): light- Depopulation Agents 1 to 7 (each mCBP (80%) emitting 1% by weight or 5% by weight): layer B TADF1 (20% by weight): add up to a total of 100% by weight, based on the light-emitting layer B of mCBP (i.e., 79% by weight or 75% by weight, respectively) 5 10 nm mCBP mCBP 4 10 nm TCTA TCTA 3 50 nm NPB NPB 2 5 nm HAT-CN HAT-CN 1 50 nm ITO ITO substrate glass glass

TABLE-US-00003 TABLE 3 Photophysical properties of layers Concen- Relative tration of Relative LT95 at Device No. depopulation E.sup.HOMO(S.sup.B)- EQE at 1200 Δλ Ex. (depopulation agent [% E.sup.HOMO(H.sup.B) 1000 cd/m.sup.2 max No. agent) by weight] [eV] cd/m.sup.2 [h] [nm] C1 C1 0 0 1 1 0 (No Depopulation Agent) E1a D1 1 0.54 1.15 3.39 3 E1b (Depopulation 5 0.54 1.01 1.41 12 Agent 1) E2a D2 1 0.48 1.08 2.64 2 E2b (Depopulation 5 0.48 1.12 2.35 2 Agent 2) E3a D3 1 0.47 0.99 4.04 2 E3b (Depopulation 5 0.47 0.98 2.11 2 Agent 3) E4a D4 1 0.3 1.01 1.99 2 E4b (Depopulation 5 0.3 1.03 1.83 2 Agent 4) E5a D5 1 0.36 1.04 2.5 2 E5b (Depopulation 5 0.36 1.06 4.2 2 Agent 5) E6a D6 1 0.36 1 1.45 2 E6b (Depopulation 5 0.36 1.02 1.33 2 Agent 6) E7a D7 1 0.16 1.01 1.04 0 E7b (Depopulation 5 0.16 1.02 1.04 0 Agent 7) Δλ max (nm) denotes the difference in the emission maximum λ .sub.max (nm) of the comparative device C1 (λ .sub.max (nm).sup.comp) and the example (λ .sub.max (nm).sup.exp): Δλ .sub.max (nm) = λ .sub.max (nm).sup.comp − λ .sub.max (nM).sup.exp.

[0319] The emitting layer of Comparative device C1 only contains TADF1 and mCBP The external quantum efficiency (FOE) at 1000 cd/m.sup.2 is 16% and the lifetime LT95 at 1200 cd/m.sup.2 value was determined to be 490 h. The emission maximum is at 520 nm at 10 mA/cm.sup.2. The corresponding CIFx value is 0.306 and CIFy is 0.604.

Device D1 comprises the same layer arrangement as device D1, except that the emitting layer contains TADF1, mCBP and Depopulation Agent 1 with either 1% by weight or 5% by weight. The concentration by weight of TADF1 is always set to 20% by weight, wherein the concentration of mCBP is either 79% by weight, in case the Depopulation Agent is used with 1% by weight or 75% by weight, in case the Depopulation Agent is used with 5% by weight.
Device D2 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 2.
Device D3 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 3.
Device D4 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 4.
Device D5 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 5.
Device D6 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 6.
Device D7 is prepared in the same manner as device D1, unless changing the Depopulation Agent 1 to Depopulation Agent 7.

[0320] It was surprisingly found that the presence of a depopulation agent may lead to an increasing lifetime in a device according to the present invention, while the EQE is at least similar, often increased. The emitted color/emission maximum wavelength typically remains in an at least similar range. For all devices with a Depopulation Agent, which shows a E.sup.HOMO(S.sup.B)−E.sup.HOMO(H.sup.B)>0.2 eV a significant enhanced LT95 at 1200 cd/m.sup.2 can be observed compared to the comparative example C1 without a Depopulation Agent and compared to example D7, as the relative lifetime LT95 at 1200 cd/m.sup.2 is enhanced by at least 30% and up to more than 300%.

ORGANIC ELECTROLUMINESCENT DEVICE EMITTING VISIBLE LIGHT

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H10K2101/30

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H10K50/11

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H10K85/322

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C09K2211/1014

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H10K50/135

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C09K11/06

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C09K2211/1018

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H10K2101/10

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H10K85/6572

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H10K50/30

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H10K85/654

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H10K2101/20

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H10K50/121

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C09K2211/1022

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H10K2102/351

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H01L51/00

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C09K11/06

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Abstract

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