CN111987228A - Blue light organic electroluminescent device - Google Patents

Abstract

The present invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising two host materials, n-type (electron transport) and p-type (hole transport) host materials, thermally activated delayed fluorescence (TADF) material and emitter material (which exhibits narrow deep blue emission of small FWHM with emission maxima from 440 nm to 475 nm). Furthermore, the invention also relates to a method for generating blue light by means of the organic electroluminescent device of the invention.

Description

blue organic electroluminescence

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

describe

Organic electroluminescent devices are of increasing importance, which contain one or more organic-based light-emitting layers, such as organic light-emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), and light-emitting transistors. In particular, OLEDs are promising devices for electronic products such as screens, displays and lighting. Organic electroluminescent devices based on organics are generally quite flexible and can be produced in particularly thin layers compared to most electroluminescent devices which are essentially based on inorganics. There are currently OLED-based screens and display devices, which exhibit particularly good vivid colors, contrast, and are also quite efficient in terms of energy consumption.

The core element of an organic electroluminescent device for light generation is the light-emitting layer placed between the anode and the cathode. When a voltage (and current) is applied to an organic electroluminescent device, holes and electrons are injected into the light-emitting layer from the anode and cathode, respectively. Typically, the hole transport layer is located between the light emitting layer and the anode, and the electron transport layer is located between the light emitting layer and the cathode. The layers are placed one after the other. Then, the recombination of holes and electrons generates high-energy excitons. The decay of such excited states (eg, such as the S1 singlet state and/or the T1 triplet state) to the ground state (S0) ideally results in light emission.

To achieve efficient energy transfer and excitation, organic electroluminescent devices contain one or more host compounds and one or more emitter compounds as dopants. Therefore, the challenge in producing organic electroluminescent devices is how to improve the device's illuminance (ie, brightness per current), obtain a desired spectrum, and achieve a desired lifetime.

There is still a need for efficient and stable OLEDs emitting in the deep blue region of the visible spectrum with small CIEy values. Therefore, there is still an unmet technical need for organic electroluminescent devices with long lifetime and high quantum yield, especially in the deep blue range.

Exciton-polaron interactions (triplet-polaron and singlet-polaron interactions) and exciton-exciton interactions (singlet-singlet, triplet-singlet and Triplet-triplet interaction) is the main pathway for device aging. Degradation pathways such as triplet-triplet annihilation (TTA) and triplet-polaron quenching (TPQ) are particularly important for deep blue emitting devices because they generate high-energy states. In particular, charged emitter molecules tend to generate high-energy excitons and/or polarons. To separate polarons and/or excitons, so-called mixed-host systems are employed, but this approach is limited due to the lack of a stable n-type host material, which has the lowest triplet state, which is not energetic enough to quench at the emitter excitons.

Another interesting parameter is the launch energy emitted by the transmitter, 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 the degradation of organic materials. 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, an emitter with a smaller FWHM is required. Furthermore, 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 is required from all materials in the light-emitting layer to the emitter material.

Efficient separation of excitons and polarons can be achieved when organic electroluminescent devices contain two host materials (TADF material and small FWHM emitter material).

Surprisingly, the present inventors discovered that the light-emitting layer of an organic electroluminescent device comprises two host materials (i.e. n-type electron transport and p-type hole transport host materials), a thermally activated delayed fluorescence (TADF) material and Emitter materials, which exhibit narrow deep blue emission, ie, small full width at half maximum FWHM, can provide organic electroluminescent devices with good lifetime and quantum yield and exhibit deep blue emission. Here, the main emission of the device originates from small FWHM emitter materials, which are especially close-range charge transfer (NRCT) emitters. Surprisingly, the energy transfer within the device is sufficient to produce a deep blue emission with a small FWHM, and thus a low CIEy color coordinate.

Accordingly, one aspect of the present invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising:

(i) the host material HN, which has the lowest excited singlet energy level ^S1N , the lowest excited triplet energy level ^T1N , and contains the highest occupied molecular orbital HOMO(HN ⁾ with energy ^{E HOMO} (HN ⁾ , and contains the lowest unoccupied molecular orbital LUMO(H ^N ) with energy E ^LUMO (H ^N );

(ii) The host material HP, which has the lowest excited singlet energy level ^S1P and the lowest excited triplet energy level ^T1P , contains the highest occupied molecular ^{orbital HOMO} (HP ⁾ with energy E ^HOMO (HP) and contains the lowest unoccupied molecular orbital LUMO(H ^P ) with energy E ^LUMO (H ^P );

(iii) Thermally activated delayed fluorescence (TADF) material EB with the lowest excited singlet energy level S1 ^E and the lowest excited triplet energy level T1 ^E with the highest occupied molecular orbital HOMO with energy ^{E HOMO} (E ^E ) (E ^E ), and the lowest unoccupied molecular orbital LUMO (E ^E ) with energy E ^LUMO (E ^E ); and

(iv) Small FWHM emitter ^SB with the lowest excited singlet energy level ^S1S and the lowest excited triplet energy level ^T1S with the highest occupied molecular orbital ^HOMO ( ^ES ) with energy EHOMO( ^ES ) , and the lowest unoccupied molecular orbital LUMO(E ^S ) with energy E ^LUMO (E ^S ), where S ^B emits light with a maximum λmax ^PMMA (S) value of 440 nm to 475 nm,

wherein the relationship represented by the following formulae (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)

E ^HOMO (H ^P )-E ^HOMO (H ^N )≥0.2eV (4b),

and satisfy the relationships represented by the following equations (5) to (8):

S1 ^N >S1 ^S (5)

S1 ^P >S1 ^S (6)

S1 ^E > S1 ^S (7)

S1 ^S <2.95eV (8).

According to the present invention, the energy of the lowest excited singlet state of the host material ^HB is higher than that of the thermally activated delayed fluorescence ( ^TADF ) material EB. ^The energy of the lowest excited singlet state of the host material HN is higher than that of the ^TADF material EB. The energy difference between the lowest unoccupied molecular orbital (LUMO) of the host material HN and the highest occupied molecular orbital (HOMO) of the host material HP is larger than the energy of the lowest excited ^singlet state of the thermally activated delayed fluorescence ( ^TADF ) material EB.

The highest occupied molecular ^orbital (HOMO) energy of the host material HP is at least 0.20 eV higher than the HOMO of the host material HN, that is, E ^HOMO (HP ⁾ is at least 0.20 eV less negative than E ^HOMO (H ^N ). The energy difference between the LUMO of H ^N and the HOMO of HP must be greater than the difference between the HOMO of H ^N and the HOMO of HP (ie, E ^LUMO (H ^N ) - E ^HOMO (H ^{P )} > E ^{HOMO (} H ^P )-E ^HOMO (H ^N )). In a preferred embodiment, the HOMO of the host material HP is more than 0.20 eV, preferably more than 0.25 eV or more preferably more than 0.30 eV higher energy than the ^HOMO of the host material H ^N. Typically, the HOMO of the host material HP is higher in energy than the ^HOMO of the host material ^HN by 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.

Alternatively, the lowest unoccupied molecular orbital (LUMO) energy of the host material HP is at least 0.20 eV higher than the LUMO of the host material HN, ie, E ^LUMO (HP ⁾ is at least 0.20 eV less negative than E ^LUMO (H ^N ). The energy difference between the LUMO of H ^N and the HOMO of HP must be greater than the difference between the LUMO of H ^N and the LUMO of HP (ie, 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 a value greater than 0.20 eV, more preferably greater than 0.25 eV or even more preferably greater than 0.30 eV. Typically, the LUMO of the host material HP is higher than the LUMO of the host material ^HN 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.

The energy of the lowest excited singlet state of the host material ^HB is higher than that of the small FWHM emitter SB. The energy of the lowest excited singlet state of the host material ^HN is higher than that of ^SB . The energy of the lowest excited singlet state of ^TADF material EB is higher than that of ^SB . The lowest excited singlet state of ^SB , the onset of the emission spectrum of ^SB , 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.

Surprisingly, it was found that the main contribution to the emission band of the optoelectronic devices of the present invention originates from the emission of ^SB , indicating the energy from ^EB to ^SB and from the host materials ^HP and ^HN to ^EB and/or ^SB fully transferred.

In one embodiment, the highest occupied molecular orbital (HOMO) energy of the host material HP is at least 0.20 eV higher than the ^HOMO of the host material H ^N , 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 The ^LUMO of HN is at least 0.20 eV higher. In a preferred embodiment, the ^HOMO energy of the host material HP is higher than the ^HOMO of the host material HN by a value greater than 0.20 eV, more preferably greater than 0.25 eV or even more preferably greater than 0.30 eV, and the ^LUMO of the host material HP Values higher than the ^LUMO of the host material HN are greater than 0.20 eV, more preferably greater than 0.25 eV or even more preferably greater than 0.30 eV.

In one embodiment, HP and ^HN form an ^exciplex . Those skilled in the art know how to select a pair of HP and HN to form an exciplex, and are aware of selection criteria - in addition to the above ^- mentioned requirements for ^HOMO- and/or LUMO ^- levels - such as low levels of ^HP and HN low steric shielding.

In one embodiment, HN is selected from the following group or a mixture of two or more selected from the following group:

In one embodiment, ^HP is selected from the following group or a mixture of two or more selected from the following group:

In one embodiment, HP and ^HN form ^exciplexes ; ^HP and ^SB do not form exciplexes; ^HN and ^SB do not form exciplexes, and ^{EB and SB do} not form exciplexes Complex.

In one embodiment, HP and HN form an ^exciplex ; ^HP and ^EB do not form an ^exciplex ; HN and ^EB do not form an ^exciplex ; ^HP and ^SB do not form an exciplex complexes; ^HN and ^SB do not form exciplexes, ^EB and ^SB do not form exciplexes.

Formation of excimer complexes between ^HP and ^EB ; ^HN and ^EB ; ^HP and ^SB ; ^HN and ^SB ; or ^EB and ^SB

In one embodiment, the HN does not contain any phosphine oxide groups, in particular the ^HN is not bis[ ^2- (diphenylphosphino)phenyl]ether oxide , DPEPO).

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

According to the invention, the TADF material is characterized in that it exhibits a ΔE _ST value, which corresponds to the energy difference between the lowest excited singlet state (S1 ) and the lowest excited triplet state (T1 ), which 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.

As used herein, the terms organic electroluminescent device and electroluminescent device can be understood in the broadest sense as any device comprising an emissive layer B comprising two host materials HP and HN, a ^TADF material ^{E B} , and the small FWHM transmitter S ^B .

An organic electroluminescent device can be understood in the broadest sense as any device based on organic materials suitable for emitting light in the visible or nearest ultraviolet (UV) range, ie in the wavelength range of 380-800 nm. More preferably, the organic electroluminescent device can emit light in the visible range, ie 400 to 800 nm.

The small FWHM emitter ^SB is chosen such that it exhibits a full width at half maximum (FWHM) emission energy in polymethylmethacrylate (PMMA) below 0.35 eV, preferably below 0.30 eV, more preferably below 0.25 eV, even More preferably below 0.20 or even below 0.15 eV. This value is λmax ^PMMA , which is the value measured in PMMA containing 10% by weight of the emitter (emitter here refers to the small FWHM emitter ^SB , where the % by weight is relative to the total content of PMMA and emitter) .

In a preferred embodiment, the organic electroluminescent device refers to an organic light emitting diode (OLED), a light emitting electrochemical cell (LEC) or a light emitting transistor.

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

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

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, especially not more than 0.1 μm.

In a preferred embodiment, the thermally activated delayed fluorescence (TADF) material EB is an organic TADF material. According to the present invention, organic emitters or organic materials means emitters or materials consisting essentially of hydrogen (H), carbon (C), nitrogen (N), boron (B), silicon (Si) and optionally fluorine (F) , optionally bromine (Br) and optionally oxygen (O) elements. Particularly preferably, it does not contain any transition metals.

In a preferred embodiment, the ^TADF material EB is an organic TADF material. In a preferred embodiment, the small FWHM transmitter ^SB is an organic transmitter. In a more preferred embodiment, both the ^TADF material EB and the small FWHM emitter ^SB are organic materials.

In a particularly preferred embodiment, the at least one ^TADF material EB is a blue TADF material, preferably a dark blue TADF material.

The compounds ^HP and ^HN and the emitters ^EB and ^SB can be included in the organic electroluminescent device in any amount and in any ratio.

In a preferred embodiment, in the organic electroluminescent device of the present invention, the amount of compound HP in the light-emitting layer ^B is greater than the amount of the emitter ^EB on a weight basis.

In a preferred embodiment, in the organic electroluminescent device of the present invention, the amount of compound HN in the light ^- emitting layer ^B is greater than the amount of the emitter EB on a weight basis.

In a preferred embodiment, in the organic electroluminescent device of the present invention, the amount of TADF material EB in light-emitting layer ^B is greater than the amount of emitter ^SB on a weight basis.

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

(i) ^10-84 % by weight of the host compound HP;

(ii) ^10-84 % by weight of the host compound HN;

(iii) 5-50% by weight of ^TADF material EB; and

(iv) 1-10% by weight of luminophore S ^B ; and optionally

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

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

(i) 10-30% by weight of the host compound ^HP ;

(ii) ^40-74 % by weight of the host compound HN;

(iii) 15-30% by weight of ^TADF material EB; and

(iv) 1-5% by weight of luminophore S ^B ; and optionally

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

In a preferred embodiment, the TADF material EB exhibits an emission maximum (ie λmax ^PMMA (EB )) in the range of ^440-470 nm, measured in polymethyl methacrylate (PMMA). In a preferred embodiment, the ^TADF material EB exhibits an emission maximum λmax ^PMMA ( ^EB ) in the range of 445 to 465 nm.

Devices with small FWHM emitters S ^B as organic blue fluorescent emitters

In one embodiment of the invention, the small FWHM emitter ^SB is an organic blue fluorescent emitter.

In one embodiment, the small FWHM emitter ^SB is an organic blue fluorescent emitter selected from the group consisting of:

In certain embodiments, the small FWHM emitter ^SB is an organic blue fluorescent emitter selected from the group consisting of:

A device in which the small FWHM emitter S ^B is a triplet-triplet annihilation (TTA) fluorescent emitter

In one embodiment of the invention, the small FWHM emitter ^SB is a blue organic triplet-triplet annihilation (TTA) emitter. In one embodiment, the small FWHM emitter ^SB is a blue organic TTA emitter selected from the group:

Small FWHM transmitter ^SB is a device for short-range charge transfer (NRCT) transmitters

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

In a preferred embodiment, the small FWHM emitter ^SB comprises or consists of polycyclic aromatic compounds.

In a preferred embodiment, the small FWHM emitter ^SB comprises (or consists of) a polycyclic aromatic compound according to formula (1) or (2) or specific examples described in US 2015/236274A. US 2015/236274 A also describes examples of synthesizing these compounds.

In one embodiment, the small FWHM transmitter ^SB includes (or consists of) a structure according to Structural Formula 1 or:

in,

n is 0 or 1.

m=1-n.

X ¹ is N or B.

X ² is N or B.

X ³ is N or B.

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

R ¹ , R ² and R ³ are each independently of each other selected from:

C ₁ -C ₅ -alkyl, which is optionally substituted by one or more substituents R ⁶ ;

_C6 - _C60 -aryl, which is optionally substituted with one or more substituents R6 ^; and

C3 _{- C57} -heteroaryl, optionally substituted by one or more substituents R6 ^;

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 , OSO ₂ R ⁵ , CF ₃ , CN, halogen, C ₁ -C ₄₀ -alkyl (which is optionally substituted by one or more substituents R ⁵ substituted, and wherein one or more non-adjacent CH ₂ -groups are each optionally 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ substituted);

C ₁ -C ₄₀ -alkoxy (which is optionally substituted by one or more substituents R ⁵ and in which one or more non-adjacent CH ₂ -groups are each optionally optionally substituted 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,SO ₂ ,NR ⁵ ,O,S or CONR ⁵ substituted;

C ₁ -C ₄₀ -thioalkoxy (which is optionally substituted by one or more substituents R5 and in which one or more non-adjacent CH ₂ -groups are each optionally 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ substituted;

C ₂ -C ₄₀ -alkenyl (which is optionally substituted by one or more substituents R5 and wherein one or more non-adjacent CH ₂ -groups are each optionally 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ substituted.

C ₂ -C ₄₀ -alkynyl (which is optionally substituted by one or more substituents R5 and in which one or more non-adjacent CH ₂ -groups are each optionally 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,SO ₂ ,NR ⁵ ,O,S or CONR ⁵ substituted;

_C6 - _C60 -aryl (optionally substituted with one or more substituents R5); and C3 ^- _{C57 -} heteroaryl (optionally substituted with one or more substituents R5 ⁾ .

R ⁵ is at each occurrence independently selected from the group consisting of hydrogen, deuterium, OPh, CF ₃ , CN, F, C ₁ -C ₅ -alkyl (wherein one or more hydrogen atoms are optionally independently of each other Deuterium, CN, CF or F substituted) _{; C 1 -C 5 -alkoxy (} wherein one or more hydrogen atoms are optionally substituted independently _of each other by deuterium, CN, CF or F);

C ₁ -C ₅ -thioalkoxy (wherein one or more hydrogen atoms are optionally substituted independently _of one another by deuterium, CN, CF or F);

C2 _{- C5alkenyl} (wherein one or more hydrogen atoms are optionally substituted independently of one another by deuterium, CN, _CF3 or F);

C2 _{- C5} -alkynyl (wherein one or more hydrogen atoms are optionally substituted independently of one another by deuterium, CN, _CF3 or F);

C ₆ -C ₁₈ -aryl (which is optionally substituted with one or more C ₁ -C ₅ -alkyl substituents);

C ₃ -C ₁₇ -heteroaryl (which is optionally substituted with one or more C ₁ -C ₅ -alkyl substituents);

N(C ₆ -C ₁₈ aryl) 2,

N(C ₃ -C _17heteroaryl ) ₂ ; and

N(C ₃ -C _17heteroaryl )(C ₆ -C ₁₈ aryl).

R ⁶ is independently at each occurrence selected from hydrogen, deuterium, OPh, CF ₃ , CN, F, C ₁ -C ₅ -alkyl (wherein one or more hydrogen atoms are optionally independently of each other deuterium, CN , CF ₃ or F substituted);

C ₁ -C ₅ -alkoxy (wherein one or more hydrogen atoms are optionally substituted independently _of one another by deuterium, CN, CF or F);

C ₁ -C ₅ -thioalkoxy (wherein one or more hydrogen atoms are optionally substituted independently _of one another by deuterium, CN, CF or F);

C2-C5 alkenyl (wherein one or more hydrogen atoms are optionally substituted independently _of one another by deuterium, CN, CF or F);

C2 _{- C5} -alkynyl (wherein one or more hydrogen atoms are optionally substituted independently of one another by deuterium, CN, _CF3 or F);

C ₆ -C ₁₈ -aryl optionally substituted with one or more C ₁ -C ₅ -alkyl substituents;

C ₃ -C ₁₇ -heteroaryl, optionally substituted with one or more C ₁ -C ₅ -alkyl substituents;

N(C ₆ -C ₁₈ aryl) 2,

N(C ₃ -C _17heteroaryl ) ₂ ; and

N(C ₃ -C _17heteroaryl )(C ₆ -C ₁₈ aryl).

According to a preferred embodiment, two or more are selected from

Substituents of R ^I , R ^II , R ^III , RIV, R ^V , R ^VI , R ^VII , R ^VIII , R ^IX , R ^X and R ^XI , which are adjacent to each other and together form a monocyclic or polycyclic ring system, so Said ring systems are aliphatic, aromatic and/or benzo-fused ring systems.

According to a preferred embodiment, at least one of X ¹ , X ² and X ³ is B, and at least one of X ¹ , X ² and X ³ is N.

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

The substituents of R ^I , R ^II , R ^III , R ^IV , R ^V , R ^VI , R ^VII , R ^VIII , R ^IX , R ^X and R ^XI are optionally selected from the same group as the adjacent one or more The substituents form aliphatic, aromatic and/or benzo-fused mono- or polycyclic ring systems,

According to a preferred embodiment of the present invention, at least one of X ¹ , X ² and X ³ is B, and at least one of X ¹ , X ² and X ³ is N.

In one embodiment, the small FWHM transmitter ^SB comprises (or consists ^of ) a structure according to Equation ¹ , and X and X are ^both N, and X is B:

In one embodiment, the small FWHM transmitter ^SB comprises (or consists ^of ) a structure according to Equation ¹ , and X and X are ^both B and X is N:

In one embodiment, the small FWHM transmitter ^SB includes (or consists of) a structure according to Equation 1, and n=0.

In one embodiment, R ¹ and R ² are each independently selected from the group consisting of:

C ₁ -C ₅ -alkyl, which is optionally substituted with one or more substituents R ⁶ ;

_C6 - _C30 -aryl, which is optionally substituted with one or more substituents R6 ^; and

C3 _{- C30} ^- heteroaryl, optionally substituted by one or more substituents R6.

In one embodiment, R ¹ and R ² are each independently selected from Me, iPr, tBu, CN, CF ₃ ,

Ph (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph);

Pyridyl (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph);

pyrimidinyl (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph); and

Triazinyl (which is optionally substituted with one or more substituents independently of one another selected from Me, iPr, tBu, CN, _CF3 and Ph).

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

Ph (which is optionally substituted with one or more substituents independently selected from the group consisting of Me, iPr, tBu, CN, CF3 and Ph);

Pyridyl (which is optionally substituted with one or more substituents independently selected from the group consisting of Me, iPr, tBu, CN, CF3 and Ph);

pyrimidinyl (which is optionally substituted with one or more substituents independently selected from each other from Me, iPr, tBu, CN, CF3 and Ph);

carbazolyl (which is optionally substituted with one or more substituents independently selected from the group consisting of Me, iPr, tBu, CN, CF3 and Ph);

triazinyl (which is optionally substituted with one or more substituents independently selected from the group consisting of Me, iPr, tBu, CN, CF3 and Ph); and

N(Ph)2.

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 of each other selected from the group consisting of hydrogen, deuterium, Halogen, Me, iPr, tBu, CN, _CF3 ,

Ph (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph);

Pyridyl (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph);

pyrimidinyl (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph);

carbazolyl (which is optionally substituted with one or more substituents independently selected from each other from Me, iPr, tBu, CN, CF and Ph ₎ ;

triazinyl (which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph); and

N(Ph) ₂ ;

Also R ¹ and R ² are each independently selected from the group consisting of:

C ₁ -C ₅ -alkyl, which is optionally substituted by one or more substituents R ⁶ ;

_C6 - _C30 -aryl, which is optionally substituted with one or more substituents R6 ^; and

C3 _{- C30} ^- heteroaryl, optionally substituted by one or more substituents R6.

In one embodiment, the small FWHM transmitter ^SB is a blue boron-containing NRCT transmitter selected from the group:

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

Preferably, the anode layer A contains a composition selected from the group consisting of indium tin oxide, indium zinc oxide, PbO, SnO, graphite, doped silicon, doped germanium, doped GaAs, doped polyaniline, doped Heteropolypyrroles, doped polythiophenes, and mixtures of two or more of the foregoing.

Preferably, the cathode layer C contains a component selected from the group consisting of:

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.

Preferably, the light-emitting layer B is located between the anode layer A and the cathode layer C. Therefore, the general setting is preferably A-B-C. This of course does not preclude the presence of one or more optional further layers. Other layers may be present on each side of A, B and/or C.

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

A) Anode layer A containing a composition 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 mixtures of two or more of the foregoing;

B) light-emitting layer B; and

C) Cathode layer C, which contains an ingredient selected from the group consisting of:

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 components,

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

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

A) Anode layer A, exemplarily comprising indium tin oxide (ITO);

HTL) hole transport layer HTL;

B) a light-emitting layer B of the invention as described herein;

ETL) electron transport layer ETL; and

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

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

In addition, organic electroluminescent devices may optionally include one or more protective layers that protect the device from harmful substances in the environment, including, for example, moisture, vapors, and/or gases.

Preferably, the anode layer A is located on the surface of the substrate. The substrate can be formed from any material or combination of materials. Most commonly, glass sheets are used as substrates. Alternatively, thin metal layers (eg, copper, gold, silver or aluminum films) or plastic films or sheets can be used. This allows for more flexibility. The anode layer A consists mainly of a (substantially) transparent film material. 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 or consists entirely of transparent conductive oxide (TCO).

Such anode layer A may exemplarily include indium tin oxide, aluminum oxide zinc, 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.

Particularly preferably, the anode layer A consists (substantially) of indium tin oxide (ITO) (eg (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, HIL can facilitate the injection of quasi-charge carriers (ie, holes) (since the transport of quasi-charge carriers from the TCO to the hole transport layer (HTL) is facilitated). The hole injection layer (HIL) may comprise poly-3,4-ethylenedioxythiophene (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC or CuI, especially a mixture of PEDOT and PSS . The hole injection layer (HIL) also prevents metal diffusion from the anode layer A into the hole transport layer (HTL). HIL may exemplarily comprise PEDOT: PSS (poly-3,4-ethylenedioxythiophene:polystyrene sulfonate), PEDOT (poly-3,4-ethylenedioxythiophene), mMTDATA (4 ,4',4"-Tris[phenyl(m-tolyl)amino]triphenylamine), spiro-TAD(2,2',7,7'-tetra(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'-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-hexaazatriphenylenehexacapronitrile) and/or spiro-NSD (N, N'-diphenyl-N,N'-bis-(1-naphthyl)-9,9'-spirobifluorene-2,7-diamine).

Adjacent to the anode layer A or the hole injection layer (HIL), a hole transport layer (HTL) is typically provided. Here, 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, which serves 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. Illustratively, the hole transport layer (HTL) may include a star-shaped heterocycle such as 3-(4-carbazolyl-9-ylphenyl)amine (TCTA), poly-TPD (poly(4-butylbenzene) yl-diphenylamine)), α-NPD (poly(4-butylphenyl-diphenylamine)), TAPC (4,4'-cyclohexyl-bis[N,N-bis(4-methyl)] phenyl)aniline]), 2-TNATA (4,4',4"-tris[2-naphthyl(phenyl)-amino]triphenylamine), spiro-TAD, DNTPD, NPB, NPNPB, MeO-TPD, HAT-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 comprise a p-doped layer, which may consist of inorganic or organic dopants in an organic hole transport matrix. Transition metal oxides such as vanadium oxide, molybdenum oxide or tungsten oxide may exemplarily be used as inorganic dopant Tetrafluorotetracyanoquinodimethane (F4-TCNQ), copper pentafluorobenzoate (Cu(I)pFBz) or transition metal complexes can be exemplarily used as organic dopants.

The EBL may exemplarily 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-dibenzofuranyl)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'-bis-(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).

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

For host compounds, unless otherwise stated, films (10% by weight of host) in polymethyl methacrylate (PMMA) onset of emission are used as Egap, which corresponds to the first excited singlet state energy of S1. For emitter compounds, unless otherwise stated, Egap and the energy of the first excited singlet state S1 are determined in the same manner as described above. For host compounds, the energy of the first excited triplet state T1 is determined from the onset of the time-gated emission spectrum at 77K, which typically has a delay time of 1 ms and an integration time of 1 ms . If not stated otherwise, the above determinations were made in polymethyl methacrylate (PMMA) films (10% by weight of the host). For TADF emitter compounds, the energy of the first excited triplet state T1 is determined from the onset of the time-gated 77K emission spectrum, which typically has a delay time of 1 ms and an integration time of 1 ms.

In the electron transport layer (ETL), any electron transporter can be used. Illustratively, electron poor compounds such as benzimidazoles, pyridines, triazoles, oxadiazoles (eg 1,3,4-oxadiazole), phosphine oxides and sulfones can be used. Illustratively, the electron transporter ETM can also be a star heterocycle, such as 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi). ETM can be exemplified by 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-bis(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 (lithium quinolate). 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 can block holes, or a hole blocking layer (HBL) can be used.

HBL can exemplarily comprise BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline=Bathocuproine), BAlq (bis(8-hydroxy-2-methylquinoline) -(4-Phenylphenoxy)aluminum), NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (aluminum-tris (8-hydroxyquinoline)), 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(carbazol)-9-yl)benzene).

The cathode layer C may be provided adjacent to the electron transport layer (ETL). Illustratively, the cathode layer C may include (or consist of) a metal (eg, Al, Au, Ag, Pt, Cu, Zn, Ni, Fe, Pb, LiF, Ca, Ba, Mg, In, W, or Pd) ) or metal alloys. For practical reasons, the cathode layer C may also consist of (substantially) opaque metals such as Mg, Ca or Al. Alternatively or additionally, the cathode layer C may also include graphite and/or carbon nanotubes (CNTs). Alternatively, the cathode layer C may also be composed of nanoscale silver wires.

Optionally, the OLED may further comprise 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)). The layer may include lithium fluoride, cesium fluoride, silver, Liq (lithium quinolate), Li2O, BaF2, MgO and/or NaF.

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

Purple: wavelength range>380-420nm;

Dark blue: wavelength range>420-475nm;

Sky blue: wavelength range>475-500nm;

Green: wavelength range>500-560nm;

Yellow: wavelength range>560-580nm;

Orange: wavelength range>580-620nm;

Red: wavelength range >620-800nm.

With regard to the emitter compound, this color refers to the emission maximum λmaxPMMA of a polymethylmethacrylate (PMMA) film with 10% by weight of the emitter. Thus, for example, the emission maximum λmaxPMMA of the dark blue emitter is in the range of 420 to 475 nm, the emission maximum of the sky blue emitter λmaxPMMA is in the range of 475 to 500 nm, and the emission maximum of the green emitter λmaxPMMA is in the range of 500 to 500 nm. In the range of 560 nm, the emission maximum λmaxPMMA of the red emitter is in the range of 620 to 800 nm.

The emission maximum λmaxPMMA of the deep blue emitter is preferably not larger than 475 nm, more preferably smaller than 470 nm, even more preferably smaller than 465 nm or even smaller than 460 nm. It is generally above 420 nm, preferably above 430 nm, 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 a preferred embodiment, the device exhibits an emission maximum λmax(D) of 440 to 475 nm. In a preferred embodiment, the device has an emission maximum λmax(D) of 450-470 nm.

Another embodiment of the present invention relates to an OLED having an external quantum efficiency at 1000cd/m2 of greater than 10%, more preferably greater than 13%, more preferably greater than 15%, even more preferably greater than 18% or even more than 20%, and/or exhibit maximum emission values 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 exhibit The LT80 value at 500 cd/m2 exceeds 100 hours, preferably exceeds 200 hours, more preferably exceeds 400 hours, even more preferably exceeds 750 hours or even exceeds 1000 hours.

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

Another aspect of the invention relates to an OLED whose light emission has CIEx and CIEy color coordinates close to CIEx (=0.131) and CIEy (=0.046), the primary colors defined in Recommendation ITU-R BT.2020 (Recommendation 2020) Light with blue CIEx and CIEy color coordinates (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 typically used, whereas the test devices used in this application are typically bottom-emitting devices (bottom electrode and substrate are transparent). When changing from a bottom-emitting device to a top-emitting device, the CIEy color coordinate of the blue device can be reduced by up to two times, while the CIEx remains almost unchanged (Okinaka et al., Abstract 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 present invention relates to an OLED whose emission has a CIEx color coordinate 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 0.08 between 0.18 or even 0.10 and 0.15, and/or the CIEy color coordinate 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.

In this application, the terms "aryl" and "aromatic" may be understood in the broadest sense to mean any monocyclic, bicyclic or polycyclic aromatic moiety. If not stated otherwise, aryl groups can also be optionally substituted with one or more substituents, which are further exemplified in this application. Thus, the term "arylene" refers to a divalent residue that has two binding sites with other molecular structures and thus serves as a linking structure. In this application, the terms "heteroaryl" and "heteroaromatic" may be understood in the broadest sense as any monocyclic, bicyclic or polycyclic heteroaromatic moiety containing at least one heteroatom, in particular each aromatic The ring has 1-3 heteroatoms. Illustratively, the heteroaromatic compound can be pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyrimidine, and the like. If not stated otherwise, heteroaryl groups can also be optionally substituted with one or more substituents, which are further exemplified in this application. Thus, the term "heteroarylene" refers to a divalent residue that has two binding sites with other molecular structures, thereby serving as linking structures.

In this application, the term "alkyl" may be understood in the broadest sense as a straight or branched chain alkyl residue. Preferred alkyl residues contain from 1 to 15 carbon atoms. Illustratively, the alkyl residue may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and the like. If not stated otherwise, alkyl groups can also be optionally substituted with one or more substituents, which are further exemplified in this application. Thus, the term "alkylene" refers to a divalent residue that has two binding sites with other molecular structures, thereby serving as linking structures.

If not stated otherwise, as used herein, especially in the context of referring to aryl, arylene, heteroaryl, alkyl, etc., the term "substituted" is to be understood in its broadest sense. Preferably, this substitution refers to a residue selected from C1-C20-alkyl, C7-C19-alkaryl and C6-C18-aryl. Thus, preferably, no charged moieties, more preferably no functional groups, are present in this substitution.

It should be noted that hydrogen can be replaced by deuterium at each occurrence.

Unless otherwise stated, any layer of the various embodiments may be positioned by any suitable method. Layers of the present invention, including light-emitting layer B, can optionally be prepared by liquid processing means (also known as "film processing", "fluid processing", "solution processing" or "solvent processing"). This means that the components in each layer are applied to the surface of the part of the device that is in liquid state. Preferably, the layers of the present invention, including the light-emitting layer B, can be prepared by spin-coating. Thin, substantially uniform layers can be obtained using this method well known to those skilled in the art.

Alternatively, the layers of the present invention, including the light-emitting layer B, can be prepared by other methods based on liquid processing methods, such as casting (eg drop casting) and rolling methods, and printing methods (eg ink jet printing, gravure printing, knife coating ). These methods can optionally be carried out in an inert atmosphere, such as in a nitrogen atmosphere.

In another preferred embodiment, the layers of the present invention may be prepared by any other method known in the art, including but not limited to vacuum processing methods known to those skilled in the art, such as thermal (co)evaporation, organic vapor deposition ( OVPD) and Organic Vapor Jet Printing (OVJP).

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

Optionally, the organic electroluminescent device (eg, OLED) may exemplarily be a substantially white organic electroluminescent device or a blue organic electroluminescent device. Illustratively, such a white organic electroluminescent device may comprise at least one (deep) blue emitter compound (eg TADF material EB) and one or more green and/or red emitting emitter compounds . Then, optionally, there may be an energy transmittance between the two or more compounds.

As a whole, the organic electroluminescent device can be formed as a thin layer with a thickness of not more than 5 mm, but more than 2 mm, more than 1 mm, more than 0.5 mm, more than 0.25 mm, more than 100 μm, or more than 10 μm.

Organic electroluminescent devices (eg, OLEDs) can be small-sized (eg, having a surface no greater than 5 mm2, or even no greater than 1 mm2), medium-sized (eg, having a surface in the range of 0.5 to 20 cm2), Or large size (for example, the surface is larger than 20cm2). Organic electroluminescent devices (eg, OLEDs) according to the present invention can optionally be used to produce screens, as large area lighting devices, light-emitting wallpapers, light-emitting window frames or panes, light-emitting labels, light-emitting devices or flexible screens or displays. In addition to common uses, organic electroluminescent devices (eg, OLEDs) can exemplarily be used as light-emitting films, "smart packaging" labels, or innovative design elements. Furthermore, they can be used for cellular detection and examination (eg, as biomarkers).

One of the main purposes of organic electroluminescent devices is to generate light. Accordingly, the present invention also relates to a method for producing light in the desired wavelength range, comprising the steps of producing any of the organic electroluminescent devices of the present invention.

Accordingly, another aspect of the present invention relates to a method for generating light in a desired wavelength range, comprising the steps of:

(i) producing an organic electroluminescent device of the present invention; and

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

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

The following examples and claims further illustrate the invention.

example

Cyclic voltammetry

Measuring cyclic voltammograms of solutions of organic molecules at a concentration of 10 ^-3 mol/l in dichloromethane (or a suitable solvent) and a suitable supporting electrolyte (eg 0.1 mol/l tetrabutylammonium hexafluorophosphate) (Cyclic voltammograms). Measurements were performed at room temperature under nitrogen atmosphere with a three-electrode assembly (working and counter electrode: Pt wire, reference electrode: Pt wire) and calibrated using FeCp ₂ /FeCp ₂ ⁺ as internal standard. HOMO data were corrected using ferrocene as an internal standard for SCE.

Density Functional Theory Calculations

Molecular structures were optimized using the BP86 functional approach and the identity resolution approach (RI). The excitation energies of the BP86-optimized structures were calculated using the time-dependent DFT (TD-DFT) method. The orbital and excited state energies were calculated using the B3LYP functional method. Numerical integration was performed with the m4 grid using the Def2-SVP basis set. The Turbomole package was used for all calculations.

photophysical measurement

Sample pretreatment: Spin-coating

Instrument: Spin150, SPS euro.

The sample concentration was 10 mg/ml, dissolved in a suitable solvent.

Program: 1) 3 seconds, 400U/min; 2) 20 seconds, 1000U/min, 1000Upm/s; 3) 10 seconds, 4000U/min, 1000Upm/s. After coating, the films were dried at 70°C for 1 minute.

Photoluminescence spectroscopy and TCSPC (Time Correlated Single Photon Counting)

Steady-state emission spectra were recorded using Horiba Scientific, Modell FluoroMax-4 equipped with a 150W xenon arc lamp, excitation and emission monochromator and Hamamatsu R928 photomultiplier tube with time-correlated single-photon counting option (time-correlated single-photon counting option). counting option). Emission and excitation spectra were corrected using standard calibration fits.

Using the same test system (equipped with FM-2013 and Horiba Yvon TCSPC hub), excited state lifetimes were determined using the TCSPC method.

Excitation source:

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

NanoLED 290 (wavelength: 294nm, pulse duration: <1ns)

SpectraLED 310 (wavelength: 314nm)

SpectraLED 355 (wavelength: 355nm).

Data analysis (exponential fit) was performed using the software suite DataStation and DAS6 analysis software. Fitted using a chi-squared-test.

Photoluminescence quantum yield measurement

For photoluminescence quantum yield (PLQY) measurements, an Absolute PL Quantum Yield Measurement C9920-03G system (Absolute PL Quantum Yield Measurement C9920-03G system, Hamamatsu Photonics) was used. Quantum yields and CIE coordinates were determined using software U6039-05 (version 3.6.0). Emission maxima are expressed in nm, quantum yield Φ is expressed in %, and CIE coordinates are expressed as x,y values.

PLQY is determined using the following scheme:

1) Quality assurance: Anthracene in ethanol (known concentration) is used as reference

2) Excitation wavelength: Determine the maximum absorption wavelength of organic molecules, and use this wavelength to excite the molecules

3) Measurement: The quantum yield of the solution or film sample was measured under nitrogen atmosphere. Yield is calculated using the following equation:

where n _photon represents the photon count and Int. represents the intensity.

Production and Characterization of Organic Electroluminescent Devices

By vacuum deposition methods, OLED devices comprising the organic molecules of the present invention can be produced. If the layer contains more than one compound, the weight percentages of the one or more compounds are given in %. The total weight percent value is 100%, so if the content of a compound is not given, the percent content of that compound is equal to the difference between the given percent content of other compounds and 100%.

For OLEDs that are not fully optimized, standard methods and the following measurements are used to characterize: measure the electroluminescence spectrum, measure the external quantum efficiency (expressed in %, which depends on the calculated intensity of the light detectable by the photodiode), and measure the current. The lifetime of the OLED device is inferred from the change in brightness during operation at constant current density. The LT50 value corresponds to the time when the measured brightness decreases to 50% of the initial brightness, similarly, the LT80 corresponds to the time when the measured brightness decreases to 80% of the initial brightness, and so on for LT97.

Accelerated lifetime measurements (eg, applying an increased current density) are employed. Exemplarily, an LT80 value of 500cd/m2 is determined using the following equation:

where L0 represents the initial brightness at the applied current density.

These values correspond to the average of several pixels (usually 2 to 8 pixels) and give the standard deviation between these pixels. The figure shows a data series for an OLED pixel.

Example D1 and Comparative Examples C1 and C2

Table 1. Properties of Materials

*Measured in 2-Me-THF solution

Table 2. Setup of example organic electroluminescent devices (OLEDs) (percentages refer to weight percent)

Device D1 produces an external quantum efficiency (EQE) of 16.8±0.3% at 1000 cd/m 2 . The LT80 value of 500cd/m2 was determined from the accelerated life measurements to be 23 hours. The emission maximum is 469 nm and the FWHM at 5W is 31 nm. The corresponding CIEy is 0.160 and CIEx is 0.127.

Comparative devices C1 and C2 comprise the same layer arrangement as device D1, except that the light emitting layers comprise only the emitters TADF1 (C1) or DABNA2 (C2).

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

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

Claims (16)

1. An organic electroluminescent device, comprising a light-emitting layer B, the light-emitting layer B comprising: (i) Host material H ^N , which has one lowest excited singlet energy level S1 ^N , one lowest excited triplet energy level T1 ^N , and one highest occupied molecular orbital HOMO(H ^N ) with energy E ^HOMO (H ^N ) and a lowest unoccupied molecular orbital LUMO(H ^N ) with energy E ^LUMO (H ^N ); (ii) The host material HP, which has one lowest excited singlet energy level ^S1P , one lowest excited triplet energy level ^T1P , one highest occupied molecular ^{orbital HOMO} (HP) with energy E ^HOMO (HP) and a LUMO(H ^P ) of the lowest unoccupied molecular orbital with energy E ^LUMO (H ^P ); (iii) Thermally activated delayed fluorescence (TADF) material EB with one lowest excited singlet energy level S1 ^E , one lowest excited triplet state energy level T1 ^E , one highest occupied molecule with energy ^{E HOMO} ( ^EE ) the orbital HOMO(E ^E ) and a lowest unoccupied molecular orbital LUMO(E ^{E ) of energy ELUMO(E E )} ; and (iv) Full width at half maximum (FWHM) emitter S ^B with one lowest excited singlet level S1 ^S , one lowest excited triplet energy level T1 ^S , one highest occupied molecular orbital HOMO (E ^S ) with energy E ^HOMO ) and a lowest unoccupied molecular orbital LUMO(E ^{S ) of energy ELUMO(E S )} , where S ^B emits light with an emission maximum λmaxP ^MMA (S) from 440 nm to 475 nm, It satisfies the relationship represented by the following equations (1) to (3) and the relationship represented by at least one of (4a) and (4b): 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), E ^HOMO (H ^P )-E ^HOMO (H ^N )≥0.2eV (4b), and satisfy the relationships represented by the following equations (5) to (8): S1 ^N >S1 ^S (5) S1 ^P >S1 ^S (6) S1 ^E > S1 ^S (7) S1 ^S <2.95eV (8). 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is selected from the group consisting of organic light emitting diodes, light emitting electrochemical cells and light emitting transistors. 3. An organic electroluminescent device according to claim 1 or 2, wherein the ^TADF material EB is an organic TADF material. 4. The organic electroluminescent device according to claim 1 or 2, which satisfies formulae (4a) and (4b). 5. The organic electroluminescent device according to claim 1 or 2, having an emission maximum λmax(D) of 440 to 475 nm. 6. The organic electroluminescent device according to claim 5, wherein the emission maximum value λmax(D) is 450-470 nm. 7. The organic electroluminescent device according to claim 1 or 2, wherein the light-emitting layer B comprises: (i) ^10-84 % by weight of the host compound HP; (ii) ^10-84 % by weight of the host compound HN; (iii) 5-50% by weight of ^TADF material EB; and (iv) 1-10% by weight of emitter S ^B . 8. The organic electroluminescent device according to claim 1 or 2, wherein the light-emitting layer B comprises: (i) 10-30% by weight of the host compound ^HP ; (ii) ^40-74 % by weight of the host compound HN; (iii) 15-30% by weight of ^TADF material EB; and (iv) 1-5% by weight of emitter S ^B . 9. The organic electroluminescent device according to claim 1 or 2, wherein the ^TADF material EB exhibits an emission maximum ^λmaxPMMA (EB) in the range of 440 to 470 nm. 10. An organic electroluminescent device according to claim 1 or 2, wherein the small FWHM emitter ^SB is an organic short-range charge transfer (NRCT) emitter. 11. The organic electroluminescent device according to claim 1 or 2, wherein the small FWHM emitter ^SB comprises or consists of a structure of formula 1:

in, n is 0 or 1; m=1-n; X ¹ is N or B; X2 is N or B ^; X ³ is N or B; W is selected from Si(R ³ ) ₂ , C(R ³ ) ₂ and BR ³ ; R ¹ , R ² and R ³ are each independently of each other selected from: C ₁ -C ₅ alkyl, which may be optionally substituted with one or more substituents R ⁶ ; C ₆ -C ₆₀ aryl, which may be optionally substituted with one or more substituents R ⁶ ; and C3 _{- C57heteroaryl} , which may be optionally substituted with one or more substituents R6 ^; 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 , OSO ₂ R ⁵ , CF ₃ , CN, Halogen, C ₁ -C ₄₀ alkyl, which may be optionally substituted with one or more substituents R ⁵ and in which one or more non-adjacent CH ₂ -groups are each optionally optionally substituted 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ ; C ₁ -C ₄₀ alkoxy, which may be optionally substituted by one or more substituents R ⁵ and in which one or more non-adjacent CH ₂ -groups are each optionally 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ ; C ₁ -C ₄₀ alkylthio, which may be optionally substituted by one or more substituents R ⁵ and in which 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ ; C ₂ -C ₄₀ alkenyl, which may be optionally substituted with one or more substituents R ⁵ and in which one or more non-adjacent CH ₂ -groups are each optionally optionally substituted 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ ; C ₂ -C ₄₀ alkynyl, which may be optionally substituted by one or more substituents R ⁵ and in which one or more non-adjacent CH ₂ -groups are each optionally 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, SO ₂ , NR ⁵ , O, S or CONR ⁵ ; C ₆ -C ₆₀ aryl, which may be optionally substituted with one or more substituents R ⁵ ; and C3 _{- C57heteroaryl} , which may be optionally substituted with one or more substituents R5 ^{; R5} is at each occurrence independently selected from the group consisting of hydrogen, deuterium, OPh, _CF3 , CN, F, C ₁ -C ₅ alkyl, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₁ -C ₅ alkoxy, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₁ -C ₅ thio, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₂ -C ₅ alkenyl, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C2 _{- C5alkynyl} , wherein optionally one or more hydrogen atoms are substituted independently of each other by deuterium, CN, _CF3 or F; C ₆ -C ₁₈ aryl, optionally substituted with one or more C ₁ -C ₅ alkyl substituents; C ₃ -C ₁₇ heteroaryl optionally substituted with one or more C ₁ -C ₅ alkyl substituents; N(C ₆ -C ₁₈ aryl) ₂ , N(C ₃ -C _17heteroaryl ) ₂ ; and N(C ₃ -C ₁₇ heteroaryl)(C ₆ -C ₁₈ aryl); R6 at each occurrence is independently selected from the group consisting of hydrogen, deuterium, OPh, _CF3 , ^CN , F, C ₁ -C ₅ alkyl, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₁ -C ₅ alkoxy, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₁ -C ₅ thio, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C ₂ -C ₅ alkenyl, wherein optionally one or more hydrogen atoms are substituted independently of one another by deuterium, CN, CF or F _; C2 _{- C5alkynyl} , wherein optionally one or more hydrogen atoms are substituted independently of each other by deuterium, CN, _CF3 or F; C ₆ -C ₁₈ aryl, optionally substituted with one or more C ₁ -C ₅ alkyl substituents; C ₃ -C ₁₇ heteroaryl optionally substituted with one or more C ₁ -C ₅ alkyl substituents; N(C ₆ -C ₁₈ aryl) ₂ , N(C ₃ -C _17heteroaryl ) ₂ ; and N(C ₃ -C ₁₇ heteroaryl)(C ₆ -C ₁₈ aryl); wherein two or more substituents 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 are adjacent to each other and form a monocyclic ring or polycyclic aliphatic, aromatic and/or benzo-fused ring systems, and wherein at least one of X ¹ , X ² and X ³ is B, and at least one of X ¹ , X ² and X ³ is N. 12. ^The organic electroluminescent device according to claim ¹¹ , wherein X1 and ^X3 are each N and X2 is B. 13. ^The organic electroluminescent device of claim ¹¹ , wherein X1 and ^X3 are each B and X2 is N. 14. The organic electroluminescent device of claim 11, wherein n=0. 15. The organic electroluminescent device according to claim 11 or 14, wherein 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, Halogen, Me, iPr, tBu, CN, _CF3 , Ph, which is optionally substituted with one or more substituents independently selected from the group consisting _of Me, iPr, tBu, CN, CF and Ph, pyridyl, which is optionally substituted with one or more substituents independently selected from one another from Me, iPr, tBu, CN, _CF and Ph, pyrimidinyl, which is optionally substituted with one or more substituents independently selected from each other from Me, iPr, tBu, CN, _CF and Ph, carbazolyl, which is optionally substituted by one or more substituents independently selected from each other from Me, iPr, tBu, CN, _CF and Ph, _Triazinyl , optionally substituted with one or more substituents independently selected from each other from Me, iPr, tBu, CN, CF and Ph, and N(Ph) ₂ ; and R ¹ and R ² are each independently selected from the group C ¹ -C ⁵ alkyl, which is optionally substituted by one or more substituents R ⁶ ; C ⁶ -C ³⁰ aryl, which is optionally substituted with one or more substituents R ⁶ ; and C3 ^{- C30} heteroaryl, optionally substituted with one or more substituents ^R6 . 16. A method for generating blue light having a wavelength of 440 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.