Blue organic electroluminescent device

Abstract

The present invention relates to an organic electroluminescent device comprising an emitting layer B comprising two host materials, namely an n-type (electron transport) and a p-type (hole transport) host material, a thermally activated delayed fluorescence (TADF) material, and an emitter material exhibiting a narrow deep blue emission with a small full width at half maximum (FWHM) and an emission maximum of 440 nm to 475 nm. Furthermore, the present invention relates to a method for generating blue light using the organic electroluminescent device of the present invention.

Description

[0001] The present invention relates to an organic electroluminescent device comprising an emitting layer B comprising two host materials, namely, an n-type (electron transporting) and a p-type (hole transporting) host material, a thermally activated delayed fluorescence (TADF) material, and an emitter material. The emitter material produces a deep blue light with a narrow (i.e., small full width at half maximum (FWHM)) emission maximum of 440 to 475 nm. The present invention also relates to a method for generating blue light using the organic electroluminescent device of the present invention.

[0002] describe

[0003] Organic electroluminescent devices (OLEDs) are gaining increasing importance. These devices contain one or more organically based light-emitting layers, such as organic light-emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), and light-emitting transistors. OLEDs, in particular, are promising devices for use in electronic products such as screens, displays, and lighting. Compared to most electroluminescent devices, which are primarily based on inorganic substances, organic-based OLEDs are generally quite flexible and can be produced in particularly thin layers. OLED-based screens and displays are already available, offering exceptionally bright colors, excellent contrast, and considerable energy efficiency.

[0004] The core element of an organic electroluminescent device for generating light is a light-emitting layer placed between an anode and a cathode. When voltage (and current) is applied to the organic electroluminescent device, holes and electrons are injected into the light-emitting layer from the anode and cathode, respectively. Typically, a hole transport layer is located between the light-emitting layer and the anode, and an electron transport layer is located between the light-emitting layer and the cathode. Each layer is placed in sequence. Then, the recombination of holes and electrons produces high-energy excitons. This excited state (for example, such as an S1 singlet state and / or a T1 triplet state) decays to a ground state (S0), ideally resulting in luminescence.

[0005] To achieve efficient energy transfer and excitation, organic electroluminescent devices (OLEDs) contain one or more host compounds and one or more emitter compounds as dopants. Therefore, the challenges in producing OLEDs are how to improve the device's illuminance (i.e., brightness per unit current), obtain a desired spectrum, and achieve a desired lifetime.

[0006] There is still a need for efficient and stable OLEDs emitting in the deep blue region of the visible spectrum with small CIEy values. Consequently, there remains an unmet technical need for organic electroluminescent devices with long lifetimes and high quantum yields, particularly in the deep blue range.

[0007] Exciton-polariton interactions (triplet-polariton and singlet-polariton interactions) and exciton-exciton interactions (singlet-singlet, triplet-singlet and triplet-triplet interactions) are the main pathways of device aging. Degradation pathways such as triplet-triplet annihilation (TTA) and triplet-polariton quenching (TPQ) are particularly important for deep blue emitting devices because they produce high energy states. In particular, charged emitter molecules tend to produce high-energy excitons and / or polaritons. In order to separate polarons and / or excitons, so-called hybrid-host systems are used, but this approach is limited by the lack of stable n-type host materials with a lowest triplet state whose energy is insufficient to quench the excitons located in the emitter.

[0008] Another interesting parameter is the initiation energy of the emitter's emission, represented by the S1 energy. If the bond dissociation energy (BDE) of the weakest bond is exceeded, high-energy photons, especially when combined with other polarons or excited states, can lead to degradation of the organic material. Therefore, the S1 energy of the emitter (the main component contributing to the emission) should be as low as possible, so for deep-blue emitting OLEDs, emitters with a small full width at half maximum (FWHM) are required. In addition, other materials - such as the host material - should not contribute to the emission, because the S1 energy of the host needs to be higher than that of the emitter to avoid quenching. Therefore, efficient energy transfer from all materials within the light-emitting layer to the emitter material is required.

[0009] When an organic electroluminescent device contains two host materials (TADF material and small FWHM emitter material), effective separation of excitons and polarons can be achieved.

[0010] Surprisingly, the present invention has found that the light-emitting layer of an organic electroluminescent device, which comprises two host materials (i.e., host materials for n-type electron transport and p-type hole transport), a thermally activated delayed fluorescence (TADF) material, and an emitter material (which exhibits a narrow deep blue emission, i.e., a small full width at half maximum FWHM), can provide an organic electroluminescent device with good lifetime and quantum yield and exhibiting deep blue emission. Here, the main emission of the device originates from a small FWHM emitter material, which is particularly a close range charge transfer (NRCT) emitter. Surprisingly, the energy transfer within the device is sufficient to produce a deep blue emission with a small FWHM, and therefore has a low CIEy color coordinate.

[0011] One aspect of the present invention therefore relates to an organic electroluminescent device comprising an emitting layer B comprising:

[0012] (i) Main material H N , which has the lowest excited singlet energy level S1 N , the lowest excited triplet state energy level T1 N , containing energy E HOMO(H N )'s highest occupied molecular orbital HOMO (H N ), and the energy content is E LUMO (H N )'s lowest unoccupied molecular orbital LUMO(H N );

[0013] (ii) Main material H P , which has the lowest excited singlet energy level S1 P and the lowest excited triplet state energy level T1 P , containing energy E HOMO (H P )'s highest occupied molecular orbital HOMO (H P ) and the energy content is E LUMO (H P )'s lowest unoccupied molecular orbital LUMO(H P );

[0014] (iii) Thermally activated delayed fluorescence (TADF) material E B , which has the lowest excited singlet energy level S1 E and the lowest excited triplet state energy level T1 E , with energy E HOMO (E E )'s highest occupied molecular orbital HOMO(E E ), and has energy E LUMO (E E )'s lowest unoccupied molecular orbital LUMO(E E );and

[0015] (iv) Small FWHM emitter S B , which has the lowest excited singlet energy level S1 S and the lowest excited triplet state energy level T1 S , with energy E HOMO (E S )'s highest occupied molecular orbital HOMO(E S ), and has energy E LUMO (E S )'s lowest unoccupied molecular orbital LUMO(E S ), where S B The maximum λmax of the emitted light PMMA (S) value is 440nm to 475nm,

[0016] wherein the relationships represented by the following equations (1) to (3) and the relationship represented by at least one of (4a) or (4b) are satisfied:

[0017] S1 N >S1E (1)

[0018] S1 P >S1 E (2)

[0019] E LUMO (H N )-E HOMO (H P )>S1 E (3)

[0020] E LUMO (H P )-E LUMO (H N )≥0.2eV (4a)

[0021] E HOMO (H P )-E HOMO (H N )≥0.2eV (4b),

[0022] And satisfy the relationships expressed by the following equations (5) to (8):

[0023] S1 N >S1 S (5)

[0024] S1 P >S1 S (6)

[0025] S1 E >S1 S (7)

[0026] S1 S <2.95eV (8).

[0027] According to the present invention, the host material H B The energy of the lowest excited singlet state is higher than that of thermally activated delayed fluorescence (TADF) materials E B The lowest excited singlet state. N The energy of the lowest excited singlet state is higher than that of TADF materials E B The lowest excited singlet state. N The energy difference between the lowest unoccupied molecular orbital (LUMO) of the host material HP and the highest occupied molecular orbital (HOMO) of the host material HP is greater than that of the thermally activated delayed fluorescence (TADF) material E B The energy of the lowest excited singlet state.

[0028] Main material H PThe highest occupied molecular orbital (HOMO) energy of the HN is at least 0.20 eV higher than that of the host material HN. HOMO (H P ) than E HOMO (H N ) is at least 0.20 eV less negative. N LUMO and H P The energy difference between the HOMOs must be greater than that of the H N The HOMO and H P The difference between the HOMO LUMO (H N )-E HOMO (H P )>E HOMO (H P )-E HOMO (H N In a preferred embodiment, the host material H P The HOMO of the host material H N The HOMO energy of the host material is greater than 0.20 eV, preferably greater than 0.25 eV or more preferably greater than 0.30 eV. P The HOMO of the host material H N The energy of the HOMO of is higher by a value less than 4.0 eV, more preferably less than 3.0 eV, even more preferably less than 2.0 eV or even less than 1.0 eV.

[0029] Alternatively, the lowest unoccupied molecular orbital (LUMO) energy of the host material HP is at least 0.20 eV higher than the LUMO energy of the host material HN, that is, E LUMO (H P ) than E LUMO (H N ) is at least 0.20 eV less negative. N LUMO and H P The energy difference between the HOMOs must be greater than that of the H N The difference between the LUMO of and the LUMO of HP (i.e., E LUMO (H N )-E HOMO (H P )>E LUMO (H P )-E LUMO (H N In a preferred embodiment, the LUMO of the host material HP is higher than the LUMO of the host material HN by more than 0.20 eV, more preferably by more than 0.25 eV or even more preferably by more than 0.30 eV. Typically, the LUMO of the host material HP is higher than the LUMO of the host material HN by more than 0.20 eV, more preferably by more than 0.25 eV or even more preferably by more than 0.30 eV. NThe LUMO of the active agent is higher by an energy of less than 4.0 eV, more preferably less than 3.0 eV, even more preferably less than 2.0 eV or even less than 1.0 eV.

[0030] Main material H B The energy of the lowest excited singlet state of H is higher than that of the emitter SB with small FWHM. N The energy of the lowest excited singlet state is higher than that of S B The lowest excited singlet state of TADF material E B The energy of the lowest excited singlet state is higher than that of S B The lowest excited singlet state. S B The lowest excited singlet state, S B The onset of the emission spectrum is less than 2.95 eV, preferably less than 2.90 eV, more preferably less than 2.85 eV, even more preferably less than 2.80 eV or even less than 2.75 eV.

[0031] Surprisingly, it was found that the main contribution to the emission band of the optoelectronic device of the present invention comes from S B The emission from E B to S B And from the main material H P and H N to E B and / or S B The energy transfer is sufficient.

[0032] In one embodiment, the host material H P The highest occupied molecular orbital (HOMO) energy is higher than that of the host material H N The HOMO of the host material HP is at least 0.20 eV higher, and the energy of the lowest unoccupied molecular orbital (LUMO) of the host material HP is higher than that of the host material H N In a preferred embodiment, the host material H P The HOMO energy of the host material H N The HOMO value of the host material H is higher by more than 0.20 eV, more preferably by more than 0.25 eV or even more preferably by more than 0.30 eV, and P LUMO than the host material H N The LUMO of is higher by a value greater than 0.20 eV, more preferably greater than 0.25 eV or even more preferably greater than 0.30 eV.

[0033] In one embodiment, H P and H N Forming an exciplex. A person skilled in the art knows how to select a pair of H P and HN to form an exciplex, and knowing the selection criteria - in addition to the above-mentioned requirements for the HOMO and / or LUMO energy levels - such as H P and H N Low steric shielding.

[0034] In one embodiment, HN is selected from the group consisting of:

[0035]

[0036] In one embodiment, H P Selected from the following group or a mixture of two or more selected from the following group:

[0037]

[0038]

[0039] In one embodiment, H P and H N Formation of excited complex; H P and S B No exciplex is formed; H N and S B No exciplex is formed, E B and S B No exciplex is formed.

[0040] In one embodiment, H P and H N Formation of excited complex; H P and E B No exciplex is formed; H N and E B No exciplex is formed; H P and S B No exciplex is formed; H N and S B No exciplex is formed, E B and S B No exciplex is formed.

[0041] H P and E B ;H N and E B ;H P and S B ;H N and S B ; or E B and S B Exciplex formation

[0042] In one embodiment, H N Does not contain any phosphine oxide groups, especially H N It is not bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO).

[0043] As used herein, the terms "TADF material" and "TADF emitter" are used interchangeably.

[0044] According to the present invention, the TADF material is characterized in that it exhibits a ΔE ST A value, which corresponds to the energy difference between the lowest excited singlet state (S1) and the lowest excited triplet state (T1), is less than 0.4 eV, preferably less than 0.3 eV, more preferably less than 0.2 eV, even more preferably less than 0.1 eV or even less than 0.05 eV. Preferred methods for determining T1 and S1 are described herein.

[0045] As used herein, the terms organic electroluminescent device and optoelectronic light-emitting device may be understood in the broadest sense as any device comprising an emitting layer B comprising two host materials H and P and H N ,TADF material E B , and small FWHM emitter S B .

[0046] An organic electroluminescent device can be understood in the broadest sense as any device based on organic materials, which is suitable for emitting light in the visible or near ultraviolet (UV) range, i.e. a wavelength in the range of 380-800 nm. More preferably, the organic electroluminescent device can emit light in the visible range, i.e. 400 to 800 nm.

[0047] Select small FWHM transmitter S B The full width at half maximum (FWHM) emission energy in polymethyl methacrylate (PMMA) is less than 0.35 eV, preferably less than 0.30 eV, more preferably less than 0.25 eV, even more preferably less than 0.20 or even less than 0.15 eV. PMMA , which is the value measured in PMMA containing 10% by weight of emitter (the emitter here refers to the small FWHM emitter S B , where the weight % is relative to the total content of PMMA and emitter).

[0048] In a preferred embodiment, the organic electroluminescent device is an organic light emitting diode (OLED), a light emitting electrochemical cell (LEC) or a light emitting transistor.

[0049] Particularly preferably, the organic electroluminescent device is an organic light emitting diode (OLED). Optionally, the organic electroluminescent device as a whole may be opaque, semi-transparent or substantially transparent.

[0050] The term "layer" as used in the context of the present invention is preferably a body having a geometrically planar shape.

[0051] The thickness of the light-emitting layer B is preferably not more than 1 mm, more preferably not more than 0.1 mm, even more preferably not more than 10 μm, even more preferably not more than 1 μm, and particularly not more than 0.1 μm.

[0052] In a preferred embodiment, the thermally activated delayed fluorescence (TADF) material EB is an organic TADF material. According to the present invention, an organic light emitter or organic material refers to a light emitter or material primarily composed of hydrogen (H), carbon (C), nitrogen (N), boron (B), silicon (Si), and optionally fluorine (F), optionally bromine (Br), and optionally oxygen (O). Particularly preferably, it does not contain any transition metals.

[0053] In a preferred embodiment, the TADF material E B is an organic TADF material. In a preferred embodiment, the small FWHM emitter S B is an organic emitter. In a more preferred embodiment, the TADF material E B and small FWHM emitter S B All are organic materials.

[0054] In a particularly preferred embodiment, at least one TADF material E B It is a blue TADF material, preferably a dark blue TADF material.

[0055] Compound H P and H N and luminous body E B and S B The organic electroluminescent device may be contained in any amount and in any ratio.

[0056] In a preferred embodiment, in the organic electroluminescent device of the present invention, the compound H in the light-emitting layer B is, based on weight, P The amount is greater than that of the luminous body E B amount.

[0057] In a preferred embodiment, in the organic electroluminescent device of the present invention, the compound H in the light-emitting layer B is, based on weight, N The amount is greater than that of the luminous body E B amount.

[0058] In a preferred embodiment, in the organic electroluminescent device of the present invention, the TADF material E in the light-emitting layer B is B The amount is greater than that of the emitter S B amount.

[0059] In a preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises:

[0060] (i) 10-84% by weight of host compound H P ;

[0061] (ii) 10-84% by weight of host compound H N ;

[0062] (iii) 5-50% by weight of TADF material E B ;and

[0063] (iv) 1-10% by weight of phosphor S B ; and optionally

[0064] (v) 0-74% by weight of one or more solvents.

[0065] In another preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises:

[0066] (i) 10-30% by weight of host compound H P ;

[0067] (ii) 40-74% by weight of host compound H N ;

[0068] (iii) 15-30% by weight of TADF material E B ;and

[0069] (iv) 1-5% by weight of phosphor S B ; and optionally

[0070] (v) 0-34% by weight of one or more solvents.

[0071] In a preferred embodiment, the TADF material EB exhibits an emission maximum (i.e., λmax) measured in polymethyl methacrylate (PMMA). PMMA (E B )) is in the range of 440-470nm. In a preferred embodiment, the TADF material E B The emission maximum λmax is in the range of 445 to 465 nm. PMMA (E B ).

[0072] Small FWHM emitter S B Device for organic blue fluorescent emitter

[0073] In one embodiment of the present invention, the small FWHM emitter S B It is an organic blue fluorescent emitter.

[0074] In one embodiment, the small FWHM emitter S B is an organic blue fluorescent emitter selected from the group consisting of:

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] In certain embodiments, the small FWHM emitter S B is an organic blue fluorescent emitter selected from the group consisting of:

[0085]

[0086]

[0087] Small FWHM emitter S B Device for triplet-triplet annihilation (TTA) fluorescent emitter

[0088] In one embodiment of the present invention, the small FWHM transmitter S B is a blue organic triplet-triplet annihilation (TTA) emitter. In one embodiment, the small FWHM emitter S B is a blue organic TTA emitter selected from the group consisting of:

[0089]

[0090] Small FWHM Emitter S B A device that is a short-range charge transfer (NRCT) transmitter

[0091] In one embodiment of the present invention, the small FWHM transmitter S B is a short-range charge transfer (NRCT) emitter. As described by Hatakeyama et al. in Advanced Materials, NRCT emitters exhibit a delayed component in time-resolved photoluminescence spectra and short-range HOMO-LUMO separation (Advanced Materials, 2016, 28(14): 2777-2781, DOI: 10.1002 / adma.201505491). In some embodiments, the NRCT emitter is a TADF material. In one embodiment, the small FWHM emitter SB is a blue boron-containing NRCT emitter.

[0092] In a preferred embodiment, the small FWHM luminophore S B Contains or consists of polycyclic aromatic compounds.

[0093] In a preferred embodiment, the small FWHM luminophore S B The invention comprises (or consists of) a polycyclic aromatic compound according to formula (1) or (2) or a specific example described in US 2015 / 236274 A. US 2015 / 236274 A also describes examples of synthesizing these compounds.

[0094] In one embodiment, the small FWHM emitter S B comprising (or consisting of) a structure according to formula 1 or:

[0095]

[0096] in,

[0097] n is 0 or 1.

[0098] m=1-n.

[0099] X 1 Is N or B.

[0100] X 2 Is N or B.

[0101] X 3 Is N or B.

[0102] W is selected from Si(R 3 )2,C(R 3 )2 and BR 3 .

[0103] R 1 , R 2 and R 3 Each independently selected from:

[0104] C1-C5-alkyl, which is optionally substituted by one or more substituents R 6 replace;

[0105] C6-C 60 - aryl, which is optionally substituted by one or more substituents R 6 Replacement; and

[0106] C3-C 57 - heteroaryl, which is optionally substituted by one or more substituents R 6 replace;

[0107] R I , R II , R III , R IV , R V , R VI , R VII , R VIII , R IX , R X and R XI are each independently selected from the group consisting of hydrogen, deuterium, N(R 5 )2,OR 5 ,Si(R 5 )3,B(OR 5 )2,OSO2R 5 ,CF3,CN,halogen,C1-C 40 -alkyl (which is optionally substituted by one or more R 5 and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 ,C≡C,Si(R 5 )2,Ge(R 5 )2,Sn(R 5 )2, C=O, C=S, C=Se, C=NR 5 ,P(=O)(R 5 ),SO,SO2,NR 5 ,O,S or CONR 5 replace);

[0108] C1-C 40 -alkoxy (which is optionally substituted by one or more R 5 and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 ,C≡C,Si(R5)2,Ge(R 5 )2,Sn(R 5 )2, C=O, C=S, C=Se, C=NR 5,P(=O)(R 5 ),SO,SO2,NR 5 ,O,S or CONR 5 replace;

[0109] C1-C 40 -thioalkoxy (which is optionally substituted by one or more substituents R5, and wherein one or more non-adjacent CH2- groups are each optionally substituted by R 5 C=CR 5 ,C≡C,Si(R 5 )2,Ge(R 5 )2,Sn(R 5 )2, C=O, C=S, C=Se, C=NR 5 ,P(=O)(R 5 ),SO,SO2,NR 5 ,O,S or CONR 5 replace;

[0110] C2-C 40 -alkenyl (which is optionally substituted with one or more substituents R5, and wherein one or more non-adjacent CH2- groups are each optionally replaced with R 5 C=CR 5 ,C≡C,Si(R 5 )2,Ge(R 5 )2,Sn(R 5 )2, C=O, C=S, C=Se, C=NR 5 ,P(=O)(R 5 ),SO,SO2,NR 5 ,O,S or CONR 5 replace.

[0111] C2-C 40 -alkynyl (which is optionally substituted with one or more substituents R5, and wherein one or more non-adjacent CH2- groups are each optionally replaced with R 5 C=CR 5 ,C≡C,Si(R 5 )2,Ge(R 5 )2,Sn(R 5 )2, C=O, C=S, C=Se, C=NR 5 ,P(=O)(R 5 ),SO,SO2,NR 5 ,O,S or CONR 5 replace;

[0112] C6-C 60 - aryl (which is optionally substituted by one or more substituents R5 substituted); and C3-C 57 -heteroaryl (which is optionally substituted by one or more R 5 replace).

[0113] R 5 is independently selected at each occurrence from the group consisting of hydrogen, deuterium, OPh, CF3, CN, F, C1-C5-alkyl (wherein one or more hydrogen atoms are optionally replaced, independently of one another, by deuterium, CN, CF3 or F); C1-C5-alkoxy (wherein one or more hydrogen atoms are optionally replaced, independently of one another, by deuterium, CN, CF3 or F);

[0114] C1-C5-thioalkoxy (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0115] C2-C5 alkenyl (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0116] C2-C5-alkynyl (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0117] C6-C 18 - aryl (which is optionally substituted by one or more C1-C5-alkyl substituents);

[0118] C3-C 17 - heteroaryl (which is optionally substituted by one or more C1-C5-alkyl substituents);

[0119] N(C6-C 18 Aryl)2,

[0120] N(C3-C 17 heteroaryl)2; and

[0121] N(C3-C 17 Heteroaryl)(C6-C 18 aryl).

[0122] R 6 is independently selected at each occurrence from hydrogen, deuterium, OPh, CF3, CN, F, C1-C5-alkyl (wherein one or more hydrogen atoms are optionally replaced independently of each other by deuterium, CN, CF3 or F);

[0123] C1-C5-alkoxy (in which one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0124] C1-C5-thioalkoxy (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0125] C2-C5 alkenyl (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0126] C2-C5-alkynyl (wherein one or more hydrogen atoms are optionally replaced independently of one another by deuterium, CN, CF3 or F);

[0127] C6-C 18 - aryl, which is optionally substituted by one or more C1-C5-alkyl substituents;

[0128] C3-C 17 - heteroaryl, which is optionally substituted by one or more C1-C5-alkyl substituents;

[0129] N(C6-C 18 Aryl)2,

[0130] N(C3-C 17 heteroaryl)2; and

[0131] N(C3-C 17 Heteroaryl)(C6-C 18 aryl).

[0132] According to a preferred embodiment, two or more selected from

[0133] R I , R II , R III ,RIV,R V , R VI , R VII , R VIII , R IX , R X and R XI The substituents are adjacent to each other and together form a monocyclic or polycyclic ring system, which is an aliphatic, aromatic and / or benzo-fused ring system.

[0134] According to a preferred embodiment, X 1 , X 2 and X 3 At least one of them is B, and X 1 , X 2 and X 3 At least one of them is N.

[0135] According to a preferred embodiment of the present invention, at least one selected from

[0136] R I , R II , R III , R IV , RV , R VI , R VII , R VIII , R IX , R X and R XI The substituents optionally form an aliphatic, aromatic and / or benzo-fused monocyclic or polycyclic ring system with one or more adjacent substituents selected from the same group,

[0137] According to a preferred embodiment of the present invention, X 1 , X 2 and X 3 At least one of them is B, and X 1 , X 2 and X 3 At least one of them is N.

[0138] In one embodiment, the small FWHM emitter S B comprising (or consisting of) a structure according to Formula 1, and X 1 and X 3 Both are N, and X 2 For B:

[0139]

[0140] In one embodiment, the small FWHM emitter S B comprising (or consisting of) a structure according to Formula 1, and X 1 and X 3 Both are B, and X 2 For N:

[0141]

[0142] In one embodiment, the small FWHM emitter S B A structure comprising (or consisting of) a structure according to Formula 1, wherein n=0.

[0143] In one embodiment, R 1 and R 2 Each independently selected from the following group:

[0144] C1-C5-alkyl, which is optionally substituted by one or more substituents R 6 replace;

[0145] C6-C 30 - aryl, which is optionally substituted by one or more substituents R 6 Replacement; and

[0146] C3-C 30 - heteroaryl, which is optionally substituted by one or more substituents R 6 replace.

[0147] In one embodiment, R 1 and R 2 Each independently selected from Me, iPr, tBu, CN, CF3,

[0148] Ph (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0149] pyridyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0150] pyrimidinyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph); and

[0151] triazine group (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph).

[0152] In one embodiment, RI, RII, RIII, RIV, RV, RVI, RVII, RVIII, RIX, RX and RXI are independently selected from the group consisting of hydrogen, deuterium, halogen, Me, iPr, tBu, CN, CF3,

[0153] Ph (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0154] pyridyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0155] pyrimidinyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0156] Carbazolyl (optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0157] triazine (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph); and

[0158] N(Ph)2.

[0159] In one embodiment, R I , R II , R III , R IV, R V , R VI , R VII , R VIII , R IX , R X and R XI are independently selected from the group consisting of hydrogen, deuterium, halogen, Me, iPr, tBu, CN, CF3,

[0160] Ph (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0161] pyridyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0162] pyrimidinyl (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0163] Carbazolyl (optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph);

[0164] triazine (which is optionally substituted by one or more substituents independently selected from Me, iPr, tBu, CN, CF3 and Ph); and

[0165] N(Ph)2;

[0166] And R 1 and R 2 Each independently selected from the following group:

[0167] C1-C5-alkyl, which is optionally substituted by one or more substituents R 6 replace;

[0168] C6-C 30 - aryl, which is optionally substituted by one or more substituents R 6 Replacement; and

[0169] C3-C 30 - heteroaryl, which is optionally substituted by one or more substituents R 6 replace.

[0170] In one embodiment, the small FWHM emitter S B is a blue boron-containing NRCT emitter selected from the group consisting of:

[0171]

[0172] Those skilled in the art will note that the organic electroluminescent device of the present invention generally contains an emitting layer B. Preferably, such an organic electroluminescent device comprises at least the following layers: at least one emitting layer B, at least one anode layer A and at least one cathode layer C.

[0173] Preferably, the anode layer A contains a component selected from the group consisting of indium tin oxide, indium zinc oxide, PbO, SnO, graphite, doped silicon, doped germanium, doped GaAs, doped polyaniline, doped polypyrrole, doped polythiophene, and a mixture of two or more of the above components.

[0174] Preferably, the cathode layer C contains components selected from the group consisting of:

[0175] Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, In, W, Pd, LiF, Ca, Ba, Mg, and mixtures and / or alloys of two or more thereof.

[0176] Preferably, the light-emitting layer B is located between the anode layer A and the cathode layer C. Thus, a general arrangement is preferably ABC. This does not, of course, exclude the presence of one or more optional additional layers. Additional layers may be present on each side of A, B and / or C.

[0177] In a preferred embodiment, the organic electroluminescent device comprises at least the following layers:

[0178] A) an anode layer A comprising a member selected from the group consisting of indium tin oxide, indium zinc oxide, PbO, SnO, graphite, doped silicon, doped germanium, doped GaAs, doped polyaniline, doped polypyrrole, doped polythiophene, and a mixture of two or more of the foregoing members;

[0179] B) light-emitting layer B; and

[0180] C) a cathode layer C, which contains a component selected from the group consisting of:

[0181] Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, In, W, Pd, LiF, Ca, Ba, Mg, and mixtures and / or alloys of two or more of the foregoing,

[0182] The light-emitting layer B is located between the anode layer A and the cathode layer C.

[0183] In one embodiment, when the organic electroluminescent device is an OLED, it may optionally comprise the following layer structure:

[0184] A) an anode layer A, exemplarily comprising indium tin oxide (ITO);

[0185] HTL) hole transport layer HTL;

[0186] B) a light-emitting layer B according to the invention as described herein;

[0187] ETL) electron transport layer ETL; and

[0188] C) Cathode layer, exemplarily comprising Al, Ca and / or Mg.

[0189] Preferably, the order of the layers here is A-HTL-B-ETL-C.

[0190] Additionally, the organic electroluminescent device may optionally include one or more protective layers to protect the device from harmful substances in the environment, including, for example, moisture, vapor and / or gas.

[0191] Preferably, the anode layer A is located on the surface of the substrate. The substrate can be formed from any material or material combination. Most commonly, a glass sheet is used as the substrate. Alternatively, a thin metal layer (e.g., copper, gold, silver or aluminum film) or a plastic film or sheet can be used. This allows for greater flexibility. The anode layer A mainly consists of the material of the (substantially) transparent film. Since at least one of the two electrodes should be (substantially) transparent to allow light emission from the OLED, one of the anode layer A and the cathode layer C is transparent. Preferably, the anode layer A contains a large content of or consists entirely of a transparent conductive oxide (TCO).

[0192] Such an anode layer A may illustratively include indium tin oxide, aluminum zinc oxide, fluorinated tin oxide, indium zinc oxide, PbO, SnO, zirconium oxide, molybdenum oxide, vanadium oxide, tungsten oxide, graphite, doped Si, doped Ge, doped GaAs, doped polyaniline, doped polypyrrole and / or doped polythiophene.

[0193] Particularly preferably, the anode layer A consists (essentially) of indium tin oxide (ITO) (e.g., (InO3)0.9(SnO2)0.1). The roughness of the anode layer A caused by the transparent conductive oxide (TCO) can be compensated by using a hole injection layer (HIL). In addition, the HIL can promote the injection of quasi-charge carriers (i.e., holes) (because the transport of quasi-charge carriers from the TCO to the hole transport layer (HTL) is promoted). The hole injection layer (HIL) may include poly-3,4-ethylenedioxythiophene (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC or CuI, in particular a mixture of PEDOT and PSS. The hole injection layer (HIL) can also prevent the diffusion of metals from the anode layer A into the hole transport layer (HTL). The HIL may illustratively comprise PEDOT:PSS (poly-3,4-ethylenedioxythiophene:polystyrenesulfonate), PEDOT (poly-3,4-ethylenedioxythiophene), mMTDATA (4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine), spiro-TAD (2,2',7,7'-tetrakis(n,n-diphenylamino)-9,9'-spirobifluorene), DNTPD (N1,N1'-(biphenyl-4,4'-diyl)bis(N1-phenyl-N4,N4-di-m-tolyl-1,4-diamine), NPB (N,N'-tris[phenyl(m-tolyl)amino]triphenylamine), -nis-(1-naphthyl)-N,N'-bis-phenyl-(1,1'-biphenyl)-4,4'-diamine), NPNPB (N,N'-diphenyl-N,N'-bis-[4-(N,N-diphenyl-amino)phenyl]benzidine), MeO-TPD (N,N,N',N'-tetrakis(4-methoxyphenyl)-benzoic acid), HAT-CN (1,4,5,8,9,11-hexaazatriphenylene hexahexanenitrile) and / or spiro-NSD (N,N'-diphenyl-N,N'-bis-(1-naphthyl)-9,9'-spirobifluorene-2,7-diamine).

[0194] A hole transport layer (HTL) is typically provided adjacent to the anode layer A or hole injection layer (HIL). Any hole transport compound can be used. For example, electron-rich heteroaromatic compounds such as triarylamines and / or carbazoles can be used as hole transport compounds. The HTL can lower the energy barrier between the anode layer A and the light-emitting layer B (serving as the light-emitting layer (EML)). The hole transport layer (HTL) can also be an electron blocking layer (EBL). Preferably, the hole transport compound has a relatively high energy level of its triplet state T1. For example, the hole transport layer (HTL) may include a star-shaped heterocycle, such as 3-(4-carbazolyl-9-ylphenyl)amine (TCTA), poly-TPD (poly(4-butylphenyl-diphenylamine)), α-NPD (poly(4-butylphenyl-diphenylamine)), TAPC (4,4′-cyclohexyl-bis[N,N-bis(4-methylphenyl)aniline]), 2-TNATA (4,4′,4″-tris[2-naphthyl(phenyl)-amino]triphenylamine), spiro TAD, DNTPD, NPB, NPNPB, MeO-TPD, H AT-CN and / or TrisPcz (9,9'-diphenyl-6-(9-phenyl-9H-carbazol-3-yl)-9H,9'H-3,3'-carbazol). In addition, the HTL may include a p-doped layer, which may be composed of an inorganic or organic dopant in an organic hole-transporting matrix. Transition metal oxides such as vanadium oxide, molybdenum oxide, or tungsten oxide may be exemplarily used as inorganic dopants. Tetrafluorotetracyanoquinodimethane (F4-TCNQ), copper pentafluorobenzoate (Cu(I)pFBz), or transition metal complexes may be exemplarily used as organic dopants.

[0195] The EBL may illustratively comprise mCP (1,3-bis(carbazol-9-yl)benzene), TCTA, 2-TNATA, mCBP (3,3-bis(9H-carbazol-9-yl)biphenyl), 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophen-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[ 3,5-bis(2-dibenzothiophenyl)phenyl]-9H-carbazole, tris-Pcz, CzSi(9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), 3',5'-di-(N-carbazolyl)-[1,1'-biphenyl]-2-carbonitrile (DCPBN; CAS 1918991-70-4), 3-(N-carbazolyl)-N-phenylcarbazole (NCNPC) and / or DCB (N,N'-dicarbazolyl-1,4-dimethylbenzene).

[0196] Orbital and excited state energies can be determined experimentally by methods known to those skilled in the art. Experimentally, the energy of the highest occupied molecular orbital (EHOMO) can be determined by cyclic voltammetry measurements known to those skilled in the art with an accuracy of 0.1 eV. The energy of the lowest unoccupied molecular orbital (ELUMO) is calculated as EHOMO + Egap, where Egap is determined as follows:

[0197] For host compounds, unless otherwise stated, the onset of emission from a film (10% by weight of the host) in polymethyl methacrylate (PMMA) was used as Egap, which corresponds to the energy of the first excited singlet state S1. For emitter compounds, unless otherwise stated, Egap and the energy of the first excited singlet state S1 were determined in the same manner as described above. For host compounds, the energy of the first excited triplet state T1 was determined from the onset of the time-gated emission spectrum at 77 K, typically with a delay time of 1 millisecond and an integration time of 1 millisecond. Unless otherwise stated, the above determination was performed in a polymethyl methacrylate (PMMA) film (10% by weight of the host). For TADF emitter compounds, the energy of the first excited triplet state T1 was determined from the onset of the time-gated emission spectrum at 77 K, typically with a delay time of 1 millisecond and an integration time of 1 millisecond.

[0198] In the electron transport layer (ETL), any electron transporter can be used. For example, electron-poor compounds such as benzimidazole, pyridine, triazole, oxadiazole (e.g., 1,3,4-oxadiazole), phosphine oxide, and sulfone can be used. For example, the electron transporter ETM can also be a star-shaped heterocycle, such as 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi). The ETM may be exemplarily NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (aluminum-tris(8-hydroxyquinoline)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphine oxide), BPyTP2 (2,7-bis(2,2′-bipyridin-5-yl)triphenyl), Sif87 (dibenzo[b,d]thiophen-2-yltriphenylsilane), Sif88 (dibenzo[b,d]thiophen-2-yl)diphenylsilane), BmPyPhB (1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene) and / or BTB (4,4′-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1′-biphenyl). Optionally, the electron transport layer may contain a dopant material such as Liq (8-hydroxyquinoline lithium). Optionally, a second electron transport layer may be located between the electron transport layer and the cathode layer C. The electron transport layer (ETL) itself may block holes, or a hole blocking layer (HBL) may be employed.

[0199] HBL may exemplarily include BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline=Bathocuproine), BAlq (bis(8-hydroxy-2-methylquinolinol)-(4-phenylphenoxy)aluminum), NBphen (2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (aluminum-tris(8-hydroxyquinolinol)), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphine oxide), T2T (2,4,6-tris(biphenyl-3-yl)-1,3, 5-triazine), T3T (2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine), TST (2,4,6-tris(9,9'-spirobifluoren-2-yl)-1,3,5-triazine), DTST (2,4-diphenyl-6-(3'-triphenylsilylphenyl)-1,3,5-triazine), DTDBF (2,8-bis(4,6-diphenyl-1,3,5-triazinyl)dibenzofuran) and / or TCB / TCP (1,3,5-tris(N-carbazolyl)benzene / 1,3,5-tris(carbazolyl)benzene).

[0200] A cathode layer C may be provided adjacent to the electron transport layer (ETL). For example, the cathode layer C may include (or consist of) a metal (e.g., Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, LiF, Ca, Ba, Mg, In, W, or Pd) or a metal alloy. For practical reasons, the cathode layer C may also consist of (substantially) opaque metals such as Mg, Ca, or Al. Alternatively or in addition, the cathode layer C may also include graphite and / or carbon nanotubes (CNTs). Alternatively, the cathode layer C may also consist of nanoscale silver wires.

[0201] Optionally, the OLED may further include a protective layer between the electron transport layer (ETL) D and the cathode layer C (which may be designated as the electron injection layer (EIL)). This layer may include lithium fluoride, cesium fluoride, silver, Liq (8-hydroxyquinoline lithium), Li2O, BaF2, MgO and / or NaF.

[0202] As used herein, if not more specifically defined in a particular context, the color of emitted and / or absorbed light is designated as follows:

[0203] Purple: wavelength range >380-420nm;

[0204] Dark blue: wavelength range >420-475nm;

[0205] Sky blue: wavelength range >475-500nm;

[0206] Green: wavelength range >500-560nm;

[0207] Yellow: wavelength range >560-580nm;

[0208] Orange: wavelength range >580-620nm;

[0209] Red: wavelength range >620-800nm.

[0210] With respect to emitter compounds, this color refers to the emission maximum λmaxPMMA of a polymethyl methacrylate (PMMA) film having 10% by weight of emitter. Thus, by way of example, the emission maximum λmaxPMMA of a deep-blue emitter lies in the range of 420 to 475 nm, the emission maximum λmaxPMMA of a sky-blue emitter lies in the range of 475 to 500 nm, the emission maximum λmaxPMMA of a green emitter lies in the range of 500 to 560 nm, and the emission maximum λmaxPMMA of a red emitter lies in the range of 620 to 800 nm.

[0211] The emission maximum λmax PMMA of the deep blue emitter is preferably no greater than 475 nm, more preferably less than 470 nm, even more preferably less than 465 nm or even less than 460 nm. It is typically greater than 420 nm, preferably greater than 430 nm, and more preferably at least 440 nm. In preferred embodiments, the device exhibits an emission maximum λmax (D) of 420 to 475 nm, 430 to 470 nm, 440 to 465 nm, or 450 to 460 nm. In preferred embodiments, the device exhibits an emission maximum λmax (D) of 440 to 475 nm. In preferred embodiments, the device has an emission maximum λmax (D) of 450 to 470 nm.

[0212] Another embodiment of the present invention relates to an OLED having an external quantum efficiency at 1000 cd / m of more than 10%, more preferably more than 13%, more preferably more than 15%, even more preferably more than 18% or even more than 20%, and / or showing an emission maximum between 420 nm and 500 nm, preferably between 430 nm and 490 nm, more preferably between 440 nm and 480 nm, even more preferably between 450 nm and 470 nm, and / or exhibiting an LT80 value at 500 cd / m of more than 100 hours, preferably more than 200 hours, more preferably more than 400 hours, even more preferably more than 750 hours or even more than 1000 hours.

[0213] Another embodiment of the present invention relates to an OLED that emits light at a specific color point. According to the present invention, the OLED has a narrow emission band, i.e., a low full width at half maximum (FWHM). In a preferred embodiment, the OLED according to the present invention emits light with a main emission peak with a FWHM below 0.30 eV, more preferably below 0.25 eV, even more preferably below 0.20 eV, or even below 0.18 eV.

[0214] Another aspect of the present invention relates to an OLED whose light emission has CIEx and CIEy color coordinates close to CIEx (=0.131) and CIEy (=0.046), i.e., the CIEx and CIEy color coordinates of the primary blue color defined in ITU-R BT.2020 Recommendation (Recommendation 2020) (CIEx=0.131 and CIEy=0.046), and is therefore suitable for ultra-high-definition (UHD) displays, such as UHD TVs. In commercial applications, top-emitting (top electrode is transparent) devices are generally used, while the test device used in this application is a typical bottom-emitting device (bottom electrode and substrate are transparent). When changing from a bottom-emitting device to a top-emitting device, the CIEy color coordinates of the blue device can be reduced by up to two times, while the CIEx remains almost unchanged (Okinaka et al., Abstracts of Technical Papers of the International Symposium of the Society for Information Display, 2015, 46(1): 312-313, DOI: 10.1002 / sdtp.10480). Therefore, another aspect of the invention relates to an OLED having an emission CIEx color coordinate of between 0.02 and 0.30, preferably between 0.03 and 0.25, more preferably between 0.05 and 0.20, or even more preferably between 0.08 and 0.18 or even between 0.10 and 0.15, and / or a CIEy color coordinate of between 0.00 and 0.45, preferably between 0.01 and 0.30, more preferably between 0.02 and 0.20, or even more preferably between 0.03 and 0.15 or even between 0.04 and 0.10.

[0215] In this application, the terms "aryl" and "aromatic" are understood in the broadest sense to mean any monocyclic, bicyclic, or polycyclic aromatic moiety. Unless otherwise specified, an aryl group may optionally be substituted with one or more substituents, as further exemplified herein. Thus, the term "arylene" refers to a divalent residue that has two binding sites for another molecular structure and thus serves as a linking structure. In this application, the terms "heteroaryl" and "heteroaromatic" are understood in the broadest sense to mean any monocyclic, bicyclic, or polycyclic heteroaromatic moiety containing at least one heteroatom, particularly with 1-3 heteroatoms per aromatic ring. Exemplary heteroaromatic compounds include pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, and pyrimidine. Unless otherwise specified, a heteroaryl group may optionally be substituted with one or more substituents, as further exemplified herein. Thus, the term "heteroarylene" refers to a divalent residue that has two binding sites for another molecular structure and thus serves as a linking structure.

[0216] In this application, the term "alkyl" is understood in the broadest sense to mean a straight-chain or branched alkyl residue. Preferred alkyl residues contain 1 to 15 carbon atoms. Illustrative examples of alkyl residues include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and the like. Unless otherwise indicated, an alkyl group may optionally be substituted with one or more substituents, which are further exemplified herein. Thus, the term "alkylene" refers to a divalent residue that has two binding sites for other molecular structures, thereby serving as a linking structure.

[0217] As used herein, the term "substituted" is to be understood in its broadest sense, unless otherwise indicated, particularly in the context of aryl, arylene, heteroaryl, alkyl, and the like. Preferably, such substitution refers to residues selected from the group consisting of C1-C20-alkyl, C7-C19-alkaryl, and C6-C18-aryl. Thus, preferably, no charged moieties, and more preferably no functional groups, are present in such substitutions.

[0218] It should be noted that hydrogen may be replaced by deuterium at each occurrence.

[0219] Unless otherwise indicated, any layer of the various embodiments can be applied by any suitable method. The layers of the present invention, including the light-emitting layer B, can optionally be prepared by liquid processing (also known as "film processing," "fluid processing," "solution processing," or "solvent processing"). This means that the components of each layer are applied to the surface of the portion of the device that is in a liquid state. Preferably, the layers of the present invention, including the light-emitting layer B, can be prepared by spin coating. This method, which is well known to those skilled in the art, can produce thin, substantially uniform layers.

[0220] Alternatively, the layers of the present invention, including the light-emitting layer B, can be prepared by other methods based on liquid processing, such as casting (e.g., drop casting) and rolling methods, and printing methods (e.g., inkjet printing, gravure printing, doctor blade coating). These methods can optionally be carried out in an inert atmosphere (e.g., in a nitrogen atmosphere).

[0221] In another preferred embodiment, the layer of the present invention can be prepared by any other method known in the art, including but not limited to vacuum processing methods well known to those skilled in the art, such as thermal (co)evaporation, organic vapor phase deposition (OVPD) and organic vapor jet printing (OVJP).

[0222] When the layer is prepared by liquid processing, the solution containing the layer components (for the light-emitting layer B of the present invention, the layer components include at least one host compound HB, typically at least one first TADF material EB, at least one second TADF material SB and optionally one or more other host compounds HB2) may further contain a volatile organic solvent. This volatile organic solvent may optionally be selected from tetrahydrofuran, dioxane, chlorobenzene, diethylene glycol diethyl ether, 2-(2-ethoxyethoxy)ethanol, γ-butyrolactone, N-methylpyrrolidone, ethoxyethanol, xylene, toluene, anisole, phenylethyl alcohol, acetonitrile, tetrahydrothiophene, benzonitrile, pyridine, trihydrofuran, triarylamine, cyclohexanone, acetone, propylene carbonate, ethyl acetate, benzene and PGMEA (propylene glycol monoethyl ether acetate). Combinations of two or more solvents may also be used. After application in a liquid state, the layer can then be dried and / or hardened by any method in the art (which may be under ambient conditions, at elevated temperature (e.g., about 50°C or about 60°C) or under reduced pressure).

[0223] Optionally, the organic electroluminescent device (e.g., OLED) can be illustratively a substantially white organic electroluminescent device or a blue organic electroluminescent device. Exemplarily, such a white organic electroluminescent device can include at least one (deep) blue emitter compound (e.g., TADF material EB) and one or more emitter compounds that emit green and / or red light. Then, optionally, there can be energy transmittance between the two or more compounds.

[0224] As a whole, the organic electroluminescent device can form a thin layer having a thickness not greater than 5 mm, but greater than 2 mm, greater than 1 mm, greater than 0.5 mm, greater than 0.25 mm, greater than 100 μm, or greater than 10 μm.

[0225] Organic electroluminescent devices (e.g., OLEDs) can be small-sized (e.g., having a surface of not more than 5 mm2, or even a surface of not more than 1 mm2), medium-sized (e.g., having a surface in the range of 0.5 to 20 cm2), or large-sized (e.g., having a surface greater than 20 cm2). The organic electroluminescent devices (e.g., OLEDs) according to the present invention can optionally be used to produce screens, as large-area lighting devices, luminous wallpaper, luminous window frames or window panes, luminous labels, luminous devices or flexible screens or displays. In addition to common uses, organic electroluminescent devices (e.g., OLEDs) can be used, for example, as luminous films, "smart packaging" labels, or innovative design elements. In addition, they can be used for cell detection and inspection (e.g., as biomarkers).

[0226] One of the main purposes of an organic electroluminescent device is to generate light. Therefore, the present invention also relates to a method for generating light in a desired wavelength range, comprising the steps of producing any of the organic electroluminescent devices of the present invention.

[0227] Therefore, another aspect of the present invention relates to a method for generating light of a desired wavelength range, comprising the steps of:

[0228] (i) producing the organic electroluminescent device of the present invention; and

[0229] (ii) applying a current to the organic electroluminescent device.

[0230] Another aspect of the present invention relates to a method for producing an organic electroluminescent device by assembling the above-mentioned elements. The present invention also relates to a method for generating blue, green, yellow, orange, red or white light, in particular blue or white light, by using the organic electroluminescent device.

[0231] The following examples and claims further illustrate the invention.

[0232] example

[0233] Cyclic voltammetry

[0234] The measured concentration was 10 -3 Cyclic voltammograms of solutions of mol / l organic molecules in dichloromethane (or a suitable solvent) and a suitable supporting electrolyte (e.g. 0.1 mol / l tetrabutylammonium hexafluorophosphate). The measurements were performed at room temperature and in a nitrogen atmosphere with a three-electrode assembly (working and counter electrodes: Pt wire, reference electrode: Pt wire) and using FeCp2 / FeCp2 + The HOMO data were corrected against SCE using ferrocene as an internal standard.

[0235] Density functional theory calculations

[0236] The molecular structure was optimized using the BP86 functional method and the identity resolution (RI) method. The excitation energies of the BP86-optimized structure were calculated using the time-dependent DFT (TD-DFT) method. Orbital and excited-state energies were calculated using the B3LYP functional method. Numerical integration was performed using the Def2-SVP basis set and an m4 grid. The Turbomole package was used for all calculations.

[0237] Photophysical measurements

[0238] Sample pretreatment: Spin-coating

[0239] Instrument: Spin150, SPS euro.

[0240] The sample concentration was 10 mg / ml and was dissolved in a suitable solvent.

[0241] Program: 1) 3 seconds, 400 U / min; 2) 20 seconds, 1000 U / min, 1000 U / s; 3) 10 seconds, 4000 U / min, 1000 U / s. After coating, the film was dried at 70°C for 1 minute.

[0242] Photoluminescence spectroscopy and TCSPC (time-correlated single photon counting)

[0243] Steady-state emission spectra were recorded using a Horiba Scientific, Model 1 FluoroMax-4 equipped with a 150W xenon arc lamp, excitation and emission monochromators, and a Hamamatsu R928 photomultiplier tube with a time-correlated single-photon counting option. Emission and excitation spectra were corrected using standard calibration fits.

[0244] The excited state lifetime was determined using the TCSPC method using the same test system (equipped with FM-2013 and Horiba Yvon TCSPC hub).

[0245] Excitation source:

[0246] NanoLED 370 (wavelength: 371nm, pulse duration: 1,1ns)

[0247] NanoLED2 90 (wavelength: 294nm, pulse duration: <1ns)

[0248] SpectraLED 310 (wavelength: 314nm)

[0249] SpectraLED 355 (wavelength: 355nm).

[0250] Data analysis (exponential fitting) was performed using the DataStation software suite and DAS6 analysis software. Chi-squared-test was used for fitting.

[0251] Photoluminescence quantum yield measurement

[0252] Photoluminescence quantum yield (PLQY) measurements were performed using the Absolute PL Quantum Yield Measurement C9920-03G system (Hamamatsu Photonics). Quantum yield and CIE coordinates were determined using software U6039-05 (version 3.6.0). The emission maximum is expressed in nm, the quantum yield Φ is expressed in %, and the CIE coordinates are expressed as x and y values.

[0253] PLQY was determined using the following scheme:

[0254] 1) Quality assurance: Anthracene in ethanol (known concentration) is used as a reference

[0255] 2) Excitation wavelength: Determine the maximum absorption wavelength of the organic molecule and use this wavelength to excite the molecule

[0256] 3) Measurement: The quantum yield of the solution or film sample was measured under a nitrogen atmosphere. The yield was calculated using the following equation:

[0257]

[0258] Among them, n photon represents the photon count and Int. represents the intensity.

[0259] Production and characterization of organic electroluminescent devices

[0260] OLED devices containing the organic molecules of the present invention can be produced by vacuum deposition. If a layer contains more than one compound, the weight percentage of the compound or compounds is given in %. The total weight percentage value is 100%, so if the content of a compound is not given, the percentage of that compound is equal to the difference between the given percentage of the other compounds and 100%.

[0261] OLEDs that are not fully optimized are characterized using standard methods and the following measurements: electroluminescence spectrum, external quantum efficiency (expressed in %, which depends on the intensity of the light detected by the photodiode), and current measurement. The lifetime of the OLED device is inferred from the change in brightness during operation at a constant current density. The LT50 value corresponds to the time it takes for the brightness to drop to 50% of the initial brightness. Similarly, the LT80 value corresponds to the time it takes for the brightness to drop to 80% of the initial brightness, and the LT97 value can be deduced similarly.

[0262] An accelerated lifetime measurement method (e.g., applying an increasing current density) is employed. Exemplarily, the LT80 value at 500 cd / m2 is determined using the following equation:

[0263]

[0264] Where L0 represents the initial brightness at the applied current density.

[0265] These values ​​correspond to the average of several pixels (usually 2 to 8 pixels) and give the standard deviation between these pixels. The data series for an OLED pixel is shown below.

[0266] Example D1 and Comparative Examples C1 and C2

[0267]

[0268] Table 1. Material properties

[0269]

[0270] *Measured in 2-Me-THF solution

[0271] Table 2. Example of an organic electroluminescent device (OLED) configuration (percentages are by weight)

[0272]

[0273]

[0274] Device D1 produces an external quantum efficiency (EQE) of 16.8±0.3% at 1000 cd / m². An LT80 value of 23 hours at 500 cd / m² was determined from accelerated lifetime measurements. The emission maximum is 469 nm, with a full width at half maximum (FWHM) of 31 nm at 5 W. The corresponding CIEy values ​​are 0.160 and CIEx values ​​are 0.127.

[0275] Comparative devices C1 and C2 comprise the same layer arrangement as device D1, except that the light-emitting layer only contains emitter TADF1 (C1) or DABNA2 (C2).

[0276] For device C1, the EQE at 1000 cd / m2 is significantly reduced to 7.7±0.1% and the lifetime is shorter (LT80 is 8 hours at 500 cd / m2). The emission maximum is 461 nm, but due to the larger FWHM of 58 nm at 5 V, the corresponding CIEy is 0.150, only slightly lower than that of D1. Furthermore, the corresponding CIEx is 0.145, which is poor compared to D1.

[0277] For device C2, the EQE at 1000 cd / m2 is 12.6 ± 0.4% lower than that of D1 and the lifetime is significantly shorter (LT80 is 6 h at 500 cd / m2). The emission maximum is 469 nm, but due to the smaller FWHM of 28 nm at 5 V, the corresponding CIEy is 0.121 and CIEx is 0.124.

Claims

1. An organic electroluminescent device, comprising a light-emitting layer B, wherein the light-emitting layer B comprises: (i) Main material H N , which has the lowest excited singlet energy level S1 N , the lowest excited triplet state energy level T1 N , energy is E HOMO (H N )'s highest occupied molecular orbital HOMO (H N ) and energy E LUMO (H N )'s lowest unoccupied molecular orbital LUMO(H N ); (ii) Main material H P , which has the lowest excited singlet energy level S1 P , the lowest excited triplet state energy level T1 P , energy is E HOMO (H P )'s highest occupied molecular orbital HOMO (H P ) and energy E LUMO (H P )'s lowest unoccupied molecular orbital LUMO(H P ); (iii) Thermally activated delayed fluorescence (TADF) materials with an energy difference of less than 0.4 eV between the lowest excited singlet state (S1) and the lowest excited triplet state (T1) B , which has the lowest excited singlet energy level S1 E , the lowest excited triplet state energy level T1 E , energy is E HOMO (E E )'s highest occupied molecular orbital HOMO(E E ) and energy E LUMO (E E )'s lowest unoccupied molecular orbital LUMO(E E );and (iv) Emitter S exhibiting an emission energy lower than 0.35 eV in PMMA B , which has the lowest excited singlet energy level S1 S , the lowest excited triplet state energy level T1 S , energy is E HOMO (E S )'s highest occupied molecular orbital HOMO(E S ), energy is E LUMO (E S )'s lowest unoccupied molecular orbital LUMO(E S ), where S B Emission has an emission maximum λ of 440nm to 475nm max PMMA (S) light, wherein the relationships represented by the following equations (1) to (3) and the relationship represented by at least one of (4a) or (4b) are satisfied: S1 N > S1 E (1) S1 P > S1 E (2) E LUMO (H N ) - E HOMO (H P ) > S1 E (3) E LUMO (H P )-E LUMO (H N )≥0.2eV(4a), HAVE BEEN HOMO (H P )-HAVE BEEN HOMO (H N )≥0.2eV(4b), And the relationships expressed by the following equations (5) to (8) are satisfied: S1 N > S1 S (5) S1 P > S1 S (6) S1 E > S1 S (7) S1 S < 2.95 eV (8). 2 . The organic electroluminescent device according to claim 1 , wherein the organic electroluminescent device is a device selected from the group consisting of an organic light emitting diode, a light emitting electrochemical cell, and a light emitting transistor.

3. The organic electroluminescent device according to any one of claims 1 or 2, wherein the TADF material E B It is an organic TADF material. 4 . The organic electroluminescent device according to claim 1 , wherein formulae (4a) and (4b) are satisfied.

5. The organic electroluminescent device according to any one of claims 1 or 2, wherein the device exhibits an emission maximum λ of 440 nm to 475 nm. max (D).

6. The organic electroluminescent device according to claim 5, wherein the device exhibits an emission maximum λ of 450 nm to 470 nm. max (D).

7. The organic electroluminescent device according to any one of claims 1 or 2, wherein the light-emitting layer B comprises: (i) 10% to 84% by weight of the host material H P ; (ii) 10% to 84% by weight of the host material H N ; (iii) 5 to 50% by weight of the TADF material E B ;and (iv) 1 to 10% by weight of said emitter S B .

8. The organic electroluminescent device according to any one of claims 1 or 2, wherein the light-emitting layer B comprises: (i) 10% to 30% by weight of the host material H P ; (ii) 40% to 74% by weight of the host material H N ; (iii) 15% to 30% by weight of the TADF material E B ;and (iv) 1 to 5% by weight of said emitter S B .

9. The organic electroluminescent device according to any one of claims 1 or 2, wherein the TADF material E B Exhibits emission maximum λ in the range of 440nm to 470nm max PMMA (E B ).

10. The organic electroluminescent device according to any one of claims 1 or 2, wherein the FWHM emitter S B It is an organic short-range charge transfer (NRCT) emitter.

11. The organic electroluminescent device according to any one of claims 1 or 2, wherein the FWHM emitter S B Comprising or consisting of a structure according to Formula 1: in n is 0 or 1; m = 1 - n; X 1 N or B; X 2 N or B; X 3 N or B; W is selected from Si(R 3 )2、C(R 3 )2 and BR 3 the group formed; R 1 、R 2 and R 3 Independently selected from the group consisting of: C1-C5 alkyl, which may be optionally substituted by one or more substituents R 6 replace; C6-C 60 Aryl, which may be optionally substituted by one or more substituents R 6 Replacement; and C3-C 57 Heteroaryl, which may be optionally substituted by one or more substituents R 6 replace; R I 、R II 、R III 、R IV 、R V 、R VI 、R VII 、R VIII 、R IX 、R X and R XI Independently selected from the group consisting of: Hydrogen, deuterium, N(R 5 )2、OR 5 、Si(R 5 )3、B(OR 5 2. OSO2R 5 , CF3, CN, halogen, C1-C 40 Alkyl, which may be optionally substituted by one or more substituents R 5 substituted and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 、C≡C、Si(R 5 )2、Ge(R 5 )2、Sn(R 5 )2. C=O, C=S, C=Se, C=NR 5 、P(=O)(R 5 )、SO、SO2、NR 5 , O, S, or CONR 5 replace; C1-C 40 Alkoxy, which may be optionally substituted by one or more substituents R 5 substituted and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 、C≡C、Si(R 5 )2、Ge(R 5 )2、Sn(R 5 )2. C=O, C=S, C=Se, C=NR 5 、P(=O)(R 5 )、SO、SO2、NR 5 , O, S, or CONR 5 replace; C1-C 40 Thioalkoxy, which may be optionally substituted by one or more substituents R 5 substituted and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 、C≡C、Si(R 5 )2、Ge(R 5 )2、Sn(R 5 )2. C=O, C=S, C=Se, C=NR 5 、P(=O)(R 5 )、SO、SO2、NR 5 , O, S, or CONR 5 replace; C2-C 40 Alkenyl, which may be optionally substituted by one or more substituents R 5 substituted and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 、C≡C、Si(R 5 )2、Ge(R 5 )2、Sn(R 5 )2. C=O, C=S, C=Se, C=NR 5 、P(=O)(R 5 )、SO、SO2、NR 5 , O, S, or CONR 5 replace; C2-C 40 Alkynyl, which may be optionally substituted by one or more substituents R 5 substituted and wherein one or more non-adjacent CH2- groups are each optionally replaced by R 5 C=CR 5 、C≡C、Si(R 5 )2、Ge(R 5 )2、Sn(R 5 )2. C=O, C=S, C=Se, C=NR 5 、P(=O)(R 5 )、SO、SO2、NR 5 , O, S, or CONR 5 replace; C6-C 60 Aryl, which may be optionally substituted by one or more substituents R 5 Replacement; and C3-C 57 Heteroaryl, which may be optionally substituted by one or more substituents R 5 replace; R 5 is independently selected at each occurrence from the group consisting of hydrogen, deuterium, OPh, CF3, CN, F, C1-C5 alkyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C1-C5 alkoxy, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C1-C5 thioalkoxy, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C2-C5 alkenyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C2-C5 alkynyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C6-C 18 aryl, optionally substituted with one or more C1-C5 alkyl substituents; C3-C 17 heteroaryl, optionally substituted with one or more C1-C5 alkyl substituents; N(C6-C 18 Aryl)2, N(C3-C 17 heteroaryl)2; and N(C3-C 17 Heteroaryl)(C6-C 18 aryl); R 6 is independently selected at each occurrence from the group consisting of hydrogen, deuterium, OPh, CF3, CN, F, C1-C5 alkyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C1-C5 alkoxy, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C1-C5 thioalkoxy, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C2-C5 alkenyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C2-C5 alkynyl, wherein optionally one or more hydrogen atoms are independently replaced by deuterium, CN, CF3 or F; C6-C 18 aryl, optionally substituted with one or more C1-C5 alkyl substituents; C3-C 17 heteroaryl, optionally substituted with one or more C1-C5 alkyl substituents; N(C6-C 18 Aryl)2, N(C3-C 17 heteroaryl)2; and N(C3-C 17 Heteroaryl)(C6-C 18 aryl); Two or more of which are selected from R I 、R II 、R III 、R IV 、R V 、R VI 、R VII 、R VIII 、R IX 、R X and R XI The substituents in the group are adjacent to each other and form a monocyclic or polycyclic aliphatic, aromatic and / or benzo-fused ring system; and where X 1 、X 2 and X 3 At least one of them is B, and X 1 、X 2 and X 3 At least one of and is N.

12. The organic electroluminescent device according to claim 11, wherein X 1 and X 3 Each is N, and X 2 For B.

13. The organic electroluminescent device according to claim 11, wherein X 1 and X 3 Each is B, and X 2 is N. The organic electroluminescent device according to claim 11 , wherein n=0.

15. The organic electroluminescent device according to claim 11, wherein R I 、R II 、R III 、R IV 、R V 、R VI 、R VII 、R VIII 、R IX 、R X and R XI Independently selected from the group consisting of: Hydrogen, deuterium, halogen, Me, i Pr, t Bu, CN, CF3, Ph, which may optionally be replaced by one or more independently selected from Me, i Pr, t Substitution by a substituent in the group consisting of Bu, CN, CF3 and Ph, Pyridyl, which may be optionally replaced by one or more independently selected from Me, i Pr, t Substitution by a substituent in the group consisting of Bu, CN, CF3 and Ph, pyrimidinyl, which may be optionally replaced by one or more independently selected from Me, i Pr, t Substitution by a substituent in the group consisting of Bu, CN, CF3 and Ph, Carbazolyl, which may be optionally replaced by one or more independently selected from Me, i Pr, t Substitution by a substituent in the group consisting of Bu, CN, CF3 and Ph, triazine group, which may be optionally replaced by one or more independently selected from Me, i Pr, t Substitution by a substituent in the group consisting of Bu, CN, CF3 and Ph, and N(Ph)2; and R 1 and R 2 Each independently of one another is selected from the group consisting of: C1-C5 alkyl, which may be optionally substituted by one or more substituents R 6 replace; C6-C 30 Aryl, which may be optionally substituted by one or more substituents R 6 Replacement; and C3-C 30 Heteroaryl, which may be optionally substituted by one or more substituents R 6 replace.

16. A method for generating blue light having a wavelength of 440 nm to 475 nm, comprising the steps of: (i) providing an organic electroluminescent device according to any one of claims 1 or 2; and (ii) applying a current to the organic electroluminescent device.

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