Organic electroluminescent devices that emit green light

Abstract

This invention relates to an organic electroluminescent device comprising an emissive layer B, said emissive layer B comprising a host material, a phosphorescent material, and an emitter material, wherein the organic electroluminescent device exhibits a narrow green emission (expressed by the small half-peak full width (FWHM)) at its emission maximum in the range of 500 nm to 560 nm. Furthermore, this invention relates to a method for generating green light by means of the organic electroluminescent device according to the invention.

Description

Technical Field

[0001] This invention relates to an organic electroluminescent device comprising an emissive layer B, wherein the emissive layer B comprises a host material, a phosphorescent material, and an emitter material, and the organic electroluminescent device exhibits a narrow green emission (expressed by the small half-peak full width (FWHM)) at the emission maximum range of 500 nm to 560 nm. Furthermore, this invention relates to a method for generating green light by means of the organic electroluminescent device according to the invention. Background Technology

[0002] Organic electroluminescent devices (OLEDs), including one or more organic-based light-emitting layers (such as organic light-emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), and light-emitting transistors), are gaining increasing importance. Specifically, OLEDs are promising devices for electronic products, such as screens, displays, and lighting devices. Unlike most electroluminescent devices that are essentially inorganic, organic-based OLEDs are generally quite flexible and can be fabricated as particularly thin layers. Currently available OLED-type screens and displays exhibit good efficiency and long lifetime, or good color purity and long lifetime, but none combine all three properties (i.e., good efficiency, long lifetime, and good color purity).

[0003] The color purity, or color point, of an OLED is typically provided by CIEx and CIEy coordinates, while the color gamut for next-generation displays is provided by so-called BT-2020 and DCPI3 values. Generally, to achieve these color coordinates, a top-emitting device is needed to adjust the color coordinates by changing the cavity. To achieve high efficiency in a top-emitting device while targeting these color gamuts, a narrow emission spectrum in a bottom-emitting device is required.

[0004] Existing phosphorescent emitters exhibit a fairly broad emission spectrum, exceeding 0.25 eV, in the broad emission of phosphorescent OLEDs (PHOLEDs), with a full width at half maximum (FWHM). The broad emission spectrum of PHOLEDs in bottom-mounted devices leads to a high loss of external coupling efficiency for top-mounted device structures while targeting the BT-2020 and DCPI3 color gamuts.

[0005] Recently, some fluorescent or thermally activated delayed fluorescence (TADF) emitters with fairly narrow emission spectra have been developed, exhibiting a wide range of emission wavelengths (FWHM) of less than or equal to 0.25 eV, making them more suitable for achieving the BT-2020 and DCPI3 color gamuts. However, such fluorescent and TADF emitters typically suffer from low efficiency due to reduced efficiency at higher brightness (i.e., the roll-off behavior of OLEDs) and low lifetime due to exciton-polaron annihilation or exciton-exciton annihilation.

[0006] Surprisingly, it has been found that an organic electroluminescent device (OLED) comprising the host material, phosphorescent material, and emitter material, exhibiting narrow green emission (represented by a small full width at half maximum (FWHM)), provides an OLED with good lifetime and quantum yield and exhibits green emission. Here, the main emission of the OLED arises from the emitter material with a small FWHM. This OLED produces green emission with a small FWHM, and thus generates CIEx and CIEy color coordinates close to the specifications defined by DCPI3 and BT2020. Summary of the Invention

[0007] Therefore, one aspect of the present invention relates to an organic electroluminescent device including a light-emitting layer B, wherein the light-emitting layer B comprises:

[0008] (i) Main material H P It has the lowest excited singlet state energy level S1 P and the lowest excited triplet energy level T1 P Possessing energy E HOMO (H P The highest occupied molecular orbital (HOMO) of H P ) and possessing energy E LUMO (H P The lowest unoccupied molecular orbital LUMO (H) P );

[0009] (ii) Phosphorescent materials E B It has the lowest excited singlet state energy level S1 E and the lowest excited triplet energy level T1 E Possessing energy E HOMO (E B The highest occupied molecular orbital (HOMO) of ) B ) and possessing energy E LUMO (E B The lowest unoccupied molecular orbital LUMO (E) B );as well as

[0010] (iii) Small half-peak full width (FWHM) emitter S B It has the lowest excited singlet state energy level S1 S and the lowest excited triplet energy level T1 S Possessing energy E HOMO (S B The highest occupied molecular orbital (HOMO) of ) B ) and possessing energy E LUMO (S B The lowest unoccupied molecular orbital (LUMO) of ) B ),

[0011] Among them, E B Transfer energy to S B And S B It emits light with a maximum emission value between 500nm and 560nm, and

[0012] Among them, the relationships represented by equations (1) to (4) below apply:

[0013] T1 E >S1 S (1)

[0014] T1 P >T1 S (2)

[0015] T1 P >T1 E (3)

[0016] T1 P >S1 E (4).

[0017] According to the invention, phosphorescent material E B The lowest excited triplet state has an energy higher than that of the small half-peak full-width emitter S. B The lowest excited singlet state. Host material H P The lowest excited triplet state has an energy higher than that of the small half-peak full-width emitter S. B The lowest excited triplet state. Host material H P The lowest excited triplet state has higher energy than phosphorescent material E B The lowest excited triplet state. Host material H P The lowest excited triplet state has higher energy than phosphorescent material E B The lowest excited singlet state.

[0018] In one embodiment, the small FWHM emitter S B It is characterized by having an emission spectrum with a full width at half maximum (FWHM) of less than or equal to 0.25 eV (i.e., ≤0.25 eV).

[0019] In one embodiment, for both the fluorescent emitter and the thermally activated delayed fluorescent emitter, an emission spectrum with a full width at half maximum (FWHM) of less than or equal to 0.25 eV was observed.

[0020] In one embodiment, for the phosphorescent emitter, no emission spectrum with a full width at half maximum (FWHM) of less than or equal to 0.25 eV was observed.

[0021] In one embodiment of the present invention, the small FWHM emitter S BIts characteristic is that it exhibits lower E values ​​than phosphorescent materials. B The full width at half maximum (FWHM) of the emission spectrum (FWHM(S) B ) <FWHM(E B The emission spectrum of )).

[0022] In a preferred embodiment, the organic electroluminescent device exhibits an emission maximum λ of 500 nm to 560 nm. max (D)

[0023] In a preferred embodiment, the organic electroluminescent device exhibits an emission maximum λ of 510 nm to 550 nm. max (D)

[0024] In a preferred embodiment, the small FWHM emitter S B It emits light with a maximum emission value between 510nm and 550nm.

[0025] In a preferred embodiment, the light-emitting layer B of the organic electroluminescent device additionally includes the host material H. N Main material H N Having the lowest excited singlet state energy level S1 N The lowest excited triplet energy level T1 N Possessing energy E HOMO (H N The highest occupied molecular orbital (HOMO) of H N ) and possessing energy E LUMO (H N The lowest unoccupied molecular orbital LUMO (H) N );

[0026] Among them, the relationships represented by the following equations (2N), (3N), and (4N) apply:

[0027] T1 N >T1 S (2N)

[0028] T1 N >T1 E (3N)

[0029] T1 N >S1 E (4N),

[0030] Furthermore, the relationships expressed by equations (5) to (12) below apply:

[0031] E LUMO (H P E LUMO (SB (5)

[0032] E LUMO (H P E LUMO (E B (6)

[0033] E HOMO (H P ) <E HOMO (S B (7)

[0034] E HOMO (H P ) <E HOMO (E B (8)

[0035] E LUMO (H N ) <E LUMO (S B (9)

[0036] E LUMO (H N ) <E LUMO (E B (10)

[0037] E HOMO (H N ) <E HOMO (S B (11)

[0038] E HOMO (H N ) <E HOMO (E B (12).

[0039] According to the invention, the main material H N The lowest excited triplet state has an energy higher than that of the small half-peak full-width emitter S. B The lowest excited triplet state. Host material H N The lowest excited triplet state has higher energy than phosphorescent material E B The lowest excited triplet state. Host material H N The lowest excited triplet state has higher energy than phosphorescent material E B The lowest excited singlet state.

[0040] In addition, the main material H P The lowest unoccupied molecular orbital (LUMO) is energized higher than that of the small half-peak full-width emitter S. B The lowest unoccupied molecular orbital (LUMO). Host material H PThe lowest unoccupied molecular orbital (LUMO) has a higher energy than that of phosphorescent materials. B The lowest unoccupied molecular orbital (LUMO).

[0041] Main material H P The highest occupied molecular orbital (HOMO) is energized below that of the small half-peak full-width emitter S. B The highest occupied molecular orbital (HOMO) of the host material H. P The highest occupied molecular orbital (HOMO) has a lower energy than that of phosphorescent materials. B The highest occupied molecular orbital (HOMO).

[0042] In addition, the main material H N The lowest unoccupied molecular orbital (LUMO) is energized below that of the small half-peak full-width emitter S. B The lowest unoccupied molecular orbital (LUMO). Host material H N The lowest unoccupied molecular orbital (LUMO) has an energy lower than that of phosphorescent materials. B The lowest unoccupied molecular orbital (LUMO).

[0043] Main material H N The highest occupied molecular orbital (HOMO) is energized below that of the small half-peak full-width emitter S. B The highest occupied molecular orbital (HOMO) of the host material H. N The highest occupied molecular orbital (HOMO) has a lower energy than that of phosphorescent materials. B The highest occupied molecular orbital (HOMO).

[0044] In one embodiment, the relationship represented by at least one of equations (2E) and (3E) and equation (1E) applies:

[0045] E LUMO (H N )-E HOMO (H P T1 E (1E)

[0046] E LUMO (H P )-E LUMO (H N ≥0.2eV (2E)

[0047] E HOMO (H P )-E HOMO (H N )≥0.2eV (3E).

[0048] Main material H NThe lowest unoccupied molecular orbital (LUMO) and the host material H P The energy difference between the highest occupied molecular orbitals (HOMOs) is greater than that of phosphorescent materials. B The energy of the lowest excited triplet state.

[0049] Main material H P The highest occupied molecular orbital (HOMO) is more energetic than that of the host material H N The HOMO level is at least 0.20 eV higher, i.e., E HOMO (H P The negative value of ) is greater than that of E HOMO (H N (At least 0.20 eV.) N LUMO and H P The energy difference between HOMOs must be greater than H N HOMO and H P The difference between HOMO (E LUMO (H N )- EHOMO (H P E HOMO (H P )-E HOMO (H N In a preferred embodiment, the main material H P The HOMO is more energy-efficient than the host material H N The HOMO is greater than 0.20 eV (more preferably greater than 0.25 eV, or even more preferably greater than 0.30 eV).

[0050] Typically, the main material H P The HOMO is more energy-efficient than the host material H N The HOMO value is 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).

[0051] Optionally, the main material H P The lowest unoccupied molecular orbital (LUMO) is more energetic than that of the host material H. N The LUMO is at least 0.20 eV higher, that is, E LUMO (H P The negative value of ) is greater than that of E LUMO (H N (At least 0.20 eV.) N LUMO and H P The energy difference between HOMOs must be greater than H N LUMO and H P The difference between LUMO (E) LUMO (HN )-E HOMO (H P E LUMO (H P )-E LUMO (H N In a preferred embodiment, the main material H P The LUMO is more energy-efficient than the host material H N The LUMO is greater than 0.20 eV (more preferably greater than 0.25 eV, or even more preferably greater than 0.30 eV). Typically, the host material H P The LUMO is more energy-efficient than the host material H N The LUMO is 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).

[0052] Surprisingly, it was found that the main contribution to the emission band of the organic electroluminescent device according to the invention can be attributed to S. B The launch indicates that from E B To S B And from the main material H P and H N To E B and / or S B The full transfer of energy.

[0053] In one embodiment, the main material H P The highest occupied molecular orbital (HOMO) is more energetic than that of the host material H N The HOMO level is at least 0.20 eV, and the host material H P The lowest unoccupied molecular orbital (LUMO) is more energetic than that of the host material H. N The LUMO is at least 0.20 eV. In a preferred embodiment, the host material H P The HOMO is more energy-efficient than the host material H N The HOMO value is greater than 0.20 eV (more preferably greater than 0.25 eV, or even more preferably greater than 0.30 eV), and the host material H P The LUMO is more energy-efficient than the host material H N The LUMO is greater than 0.20 eV (more preferably greater than 0.25 eV, or even more preferably greater than 0.30 eV).

[0054] In one embodiment, H P and H N This forms an exciplex. Those skilled in the art know how to select the H atoms that form the exciplex. P and H NFor selection criteria other than the HOMO and / or LUMO energy level requirements mentioned above (such as H P and H N (Low-space shielding).

[0055] In one embodiment, H P Selected from the group consisting of two or more of the following:

[0056]

[0057]

[0058]

[0059] In one embodiment, H N Selected from the group consisting of two or more of the following:

[0060]

[0061] In one embodiment, H P and H N Formation of excitocomplex; H P and S B No excitocomplex is formed; H N and S B No excitocomplex is formed, E B and S B It does not form excitocomplexes.

[0062] In one embodiment, H P and H N Formation of excitocomplex; H P and E B No excitocomplex is formed; H N and E B No excitocomplex is formed; H P and S B No excitocomplex is formed; H N and S B No excitocomplex is formed, E B and S B It does not form excitocomplexes.

[0063] 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 The formation of excitocomplexes.

[0064] In one embodiment, H N It does not contain any phosphine oxide groups; specifically, H N It is not bis[2-(diphenylphosphino)phenyl] ether oxide (DPEPO). Detailed Implementation

[0065] As used herein, the terms organic electroluminescent device and photoelectric luminescent device may be understood in the broadest sense as any device including an emitting layer B, which comprises the host material H. P Phosphorescent materials E B and small FWHM emitter S B .

[0066] Organic electroluminescent devices can be understood in the broadest sense as any device based on organic materials suitable for emitting light in the visible light or closest to ultraviolet (UV) range (i.e., in the wavelength range of 380 nm to 800 nm). More preferably, organic electroluminescent devices can emit light in the visible light range (i.e., in the wavelength range of 400 nm to 800 nm).

[0067] In a preferred embodiment, the organic electroluminescent device is selected from the group consisting of organic light-emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), and light-emitting transistors.

[0068] Particularly preferred is the organic light-emitting device, which is an organic light-emitting diode (OLED). Optionally, the organic light-emitting device as a whole may be opaque, translucent, or (substantially) transparent.

[0069] As used in the context of this invention, the term "layer" preferably refers to a body having a broad planar geometry.

[0070] The light-emitting layer B preferably has a thickness of no more than 1 mm (more preferably no more than 0.1 mm, even more preferably no more than 10 μm, even more preferably no more than 1 μm, specifically no more than 0.1 μm).

[0071] In a preferred embodiment, the small half-peak full width (FWHM) emitter S B It is an organic material. According to the invention, an organic emitter or organic material means that the emitter or material (mainly) is composed of the elements 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.

[0072] In a preferred embodiment, the small half-peak full width (FWHM) emitter S BIt is an organic TADF material. In a preferred embodiment, the small FWHM emitter S B It is an organic emitter.

[0073] Compound H P and H N and the emitter E B and S B It can be included in organic electroluminescent devices in any amount and in any proportion.

[0074] In a preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises, by weight, a portion of the emitter E. B More compounds H P .

[0075] In a preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises, by weight, a portion greater than the emitter E. B More compounds H N .

[0076] In a preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises, by weight, a portion of the emitter S. B More TADF materials E B .

[0077] In H N In an optional preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises (or is composed of) the following components:

[0078] (i) 10 wt% to 84 wt% of the main compound H P ;

[0079] (ii) 0% to 84% by weight of the main compound H N ;

[0080] (iii) 5% to 15% by weight of phosphorescent material E B ;and

[0081] (iv) 1% to 10% by weight of small FWHM emitters B ; and optionally

[0082] (v) 0% to 72% by weight of one or more solvents.

[0083] In H N In an optional preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises (or is composed of) the following components:

[0084] (i) 22% to 70% by weight of the host compound HP ;

[0085] (ii) 0% to 70% by weight of the main compound H N ;

[0086] (iii) 5% to 10% by weight of phosphorescent material E B ;and

[0087] (iv) 1% to 5% by weight of emitter S B ; and optionally

[0088] (v) 0% to 72% by weight of one or more solvents.

[0089] In the existence of H N In another preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises (or is composed of) the following components:

[0090] (i) 10% to 30% by weight of the host compound H P ;

[0091] (ii) 40% to 74% by weight of the main compound H N ;

[0092] (iii) 15% to 30% by weight of phosphorescent material E B ;and

[0093] (iv) 1% to 5% by weight of small FWHM emitters B ; and optionally

[0094] (v) 0% to 34% by weight of one or more solvents.

[0095] In the existence of H N In another preferred embodiment, in the organic electroluminescent device of the present invention, the light-emitting layer B comprises (or is composed of) the following components:

[0096] (i) 40% to 74% by weight of the main compound H N ;

[0097] (ii) 10% to 30% by weight of the host compound H P ;

[0098] (iii) 15% to 30% by weight of phosphorescent material E B ;and

[0099] (iv) 1% to 5% by weight of small FWHM emitters B ; and optionally

[0100] (v) 0% to 34% by weight of one or more solvents.

[0101] In a preferred embodiment, phosphorescent material E B It exhibits a maximum emission value (λ) in the range of 500 nm to 540 nm (as measured in poly(methyl methacrylate) (PMMA). max PMMA (E B In a preferred embodiment, phosphorescent material E B It exhibits a maximum emission λ in the range of 490nm to 530nm. max PMMA (E B ).

[0102] Phosphorescent materials

[0103] Phosphorescent materials utilize intramolecular spin-orbit interactions (heavy atom effect) induced by metal atoms to achieve light emission from the triplet state. Examples of such phosphorescent materials include compounds represented by the general formula EI below.

[0104]

[0105] In EI, M is selected from the group consisting of Ir, Pt, Au, Eu, Ru, Re, Ag and Cu;

[0106] n is an integer from 1 to 3; and

[0107] Both X and Y are independently bidentate monoanion ligands.

[0108] Examples of compounds represented by formula EI include compounds represented by the following general formulas E-II or E-III:

[0109]

[0110] In formulas E-II and E-III, X' is an aromatic ring in which carbon (C) is bonded to M, and Y' is a complex containing nitrogen (N) coordinated to M to form a ring.

[0111] X' and Y' are bonded, and X' and Y' can form new rings. In formula E-III, Z is a bidentate ligand with two oxygen (O) atoms. In formulas E-II and E-III, from the viewpoint of high efficiency and long lifetime, M is preferably Ir.

[0112] In formulas E-II and E-III, the aromatic ring X' can be, for example, C6-C. 30 Aryl, C6-C 16 aryl (or even more preferably C6-C) 12Aryl, particularly preferably C6-C 10 (aryl), wherein X' may optionally replace one or more substituents R each time it appears. E .

[0113] In E-II and E-III, Y' can be, for example, C2-C 30 heteroaryl, C2-C 25 Heteroaryl (more preferably C2-C) 20 heteroaryl, or even more preferably C2-C 15 heteroaryl, particularly preferably C2-C 10 (heteroaryl), wherein Y' may optionally replace one or more substituents R each time it appears. E Furthermore, Y' can optionally be substituted with one or more substituents R. E C1-C5 heteroaryl groups.

[0114] In formulas E-II and E-III, the bidentate ligand Z having two oxygen atoms (O) can be, for example, a C2-C ligand having two oxygen atoms. 30 Didentate ligand, C2-C with two oxygen atoms 25 Didentate ligands (more preferably C2-C with two oxygen atoms) 20 Didentate ligands, or even more preferably, C2-C with two oxygen atoms. 15 Didentate ligands, particularly preferably C2-C having two oxygen atoms. 10 (binder ligand), wherein Z may optionally replace one or more substituents R each time it appears. E Furthermore, Z can optionally replace one or more substituents R. E It has two oxygen atoms and is a C2-C5 bidentate ligand.

[0115] R E Each time it appears, it can be independently selected from the group consisting of: hydrogen; deuterium; N(R) 5E )2; OR 5E ;SR 5E ;Si(R) 5E )3; CF3; CN; Halogen; C1-C 40 Alkyl groups may optionally be substituted with one or more substituents R. 5E And wherein, one or more non-adjacent CH2 groups are optionally R 5E C = CR 5E C≡C, Si(R) 5E )2、Ge(R 5E )2、Sn(R 5E )2. C=O, C=S, C=Se, C=NR 5EP(=O)(R) 5E SO, SO2, NR 5E O, S or CONR 5E Replacement; C1-C 40 Thioalkoxy groups may optionally be substituted with one or more substituents R. 5E And wherein, one or more non-adjacent CH2 groups are optionally R 5E C = CR 5E C≡C, Si(R) 5E )2、Ge(R 5E )2、Sn(R 5E )2. C=O, C=S, C=Se, C=NR 5E P(=O)(R) 5E SO, SO2, NR 5E O, S or CONR 5E Replacement; C6-C 60 The aryl group may optionally be substituted with one or more substituents R. 5E ; and C3-C 57 Heteroaryl groups may optionally be substituted with one or more substituents R. 5E ;

[0116] R 5E Each time it appears, it can be independently selected from the group consisting of: hydrogen; deuterium; N(R) 6E )2; OR 6E ;SR 6E ;Si(R) 6E )3; CF3; CN; F; C1-C 40 Alkyl groups may optionally be substituted with one or more substituents R. 6E And wherein, one or more non-adjacent CH2 groups are optionally R 6E C = CR 6E C≡C, Si(R) 6E )2、Ge(R 6E )2、Sn(R 6E )2. C=O, C=S, C=Se, C=NR 6E 、P(=O)(R 6E SO, SO2, NR 6E O, S or CONR 6E Replacement; C6-C 60 The aryl group may optionally be substituted with one or more substituents R. 6E ; and C3-C 57 Heteroaryl groups may optionally be substituted with one or more substituents R. 6E ;

[0117] R 6E Each occurrence may be independently selected from the group consisting of: hydrogen; deuterium; OPh; CF3; CN; F; C1-C5 alkyl, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 alkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 thioalkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C6-C 18 The aryl group may optionally be replaced by one or more C1-C5 alkyl substituents; C3-C 17 Heteroaryl groups may optionally be 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 (C6-C) 18 Aryl).

[0118] Optionally, the substituent R E R 5E Or R 6E They can be optionally coupled with one or more substituents R independently of each other. E R 5E R 6E And / or form monocyclic or polycyclic aliphatic, aromatic, heteroaromatic and / or benzo[a] fused ring systems with X', Y' and Z.

[0119] Examples of compounds represented by formula E-II include Ir(ppy)3, Ir(ppy)2(acac), Ir(mppy)3, Ir(PPy)2(m-bppy), BtpIr(acac), Ir(btp)2(acac), Ir(2-phq)3, Hex-Ir(phq)3, Ir(fbi)2(acac), faceted tris(2-(3-p-xylyl)phenyl)pyridineiridium(III), Eu(dbm)3(Phen), Ir(piq)3, Ir(piq)2(acac), Ir(Fiq)2(acac), Ir(Flq)2(acac), Ru(dtb-bpy) 3·2(PF6), Ir(2-phq)3, Ir(BT)2(acac), Ir(DMP)3, Ir(Mpq)3, Ir(phq)2tpy, surface type-Ir(ppy)2Pc, Ir(dp)PQ 2. Ir(Dpm)(Piq)2, Hex-Ir(piq)2(acac), Hex-Ir(piq)3, Ir(dmpq)3, Ir(dmpq)2(acac), FPQIrpic, etc.

[0120] Other examples of compounds represented by formula E-II include those represented by formulas E-II-1 to E-II-11 below. In the structural formula, "Me" represents a methyl group.

[0121]

[0122] Other examples of compounds represented by formula E-III include those represented by formulas E-III-1 through E-III-6 below. In the structural formula, "Me" represents a methyl group.

[0123]

[0124] In addition, iridium complexes described in US-A2003 / 017361, US-A2004 / 262576, WO2010 / 027583, US-A2019 / 245153, US-A2013 / 119354 and / or US-A2019 / 233451 can be used. From the viewpoint of high efficiency of phosphorescent materials, Ir(ppy)3 and Hex-Ir(ppy)3 are used for green light emission.

[0125] Small FWHM emitter material

[0126] Preferably, the small FWHM emitter S B It is characterized by having an emission spectrum with a full width at half maximum (FWHM) of less than or equal to 0.25 eV (i.e., ≤0.25 eV).

[0127] Preferably, a small FWHM emitter S is selected. B To exhibit emission with a full width at half maximum (FWHM) of less than 0.25 eV (preferably less than 0.20 eV, even more preferably less than 0.15 eV) in PMMA.

[0128] In one embodiment of the invention, the small FWHM emitter S B Selected from the group consisting of fluorescent emitters and thermally activated delayed fluorescent emitters.

[0129] As used herein, the terms “fluorescent material” and “fluorescent emitter” may be understood interchangeably.

[0130] According to the present invention, the fluorescent material is characterized by exhibiting a ΔE greater than 0.4 eV. ST Value, ΔE ST The value corresponds to the energy difference between the lowest excited singlet state (S1) and the lowest excited triplet state (T1).

[0131] As used herein, the terms “TADF material” and “TADF emitter” may be understood interchangeably.

[0132] According to the present invention, the TADF material is characterized by exhibiting a ΔE of 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). ST Value, ΔE ST The value corresponds to the energy difference between the lowest excited singlet state (S1) and the lowest excited triplet state (T1).

[0133] According to the present invention, a ΔE of 0.4 eV is exhibited. ST The material with the value ΔE is characterized as a TADF material. ST The value corresponds to the energy difference between the lowest excited singlet state (S1) and the lowest excited triplet state (T1).

[0134] In one embodiment of the invention, the small FWHM emitter S B It is an organic green fluorescent emitter.

[0135] Among them, the small FWHM emitter S B Devices containing boron (B) emitters

[0136] In one embodiment, the small FWHM emitter S B It is a green boron-containing emitter. The small green boron-containing FWHM emitter S B Examples include compounds represented by the general formula BI below:

[0137]

[0138] Where B is boron,

[0139] Ar 1 Ar 2 and Ar 3 Each time it appears, it is independently selected from the group consisting of aromatic rings and heteroaromatic rings.

[0140] And Ar 1 Ar 2 and Ar 3They can optionally be connected to each other to form a loop.

[0141] Ar, as a general formula BI 1 Ar 2 and Ar 3 The aromatic ring can be, for example, an aromatic ring having 6 to 30 carbon atoms, and the aromatic ring can preferably be an aromatic ring having 6 to 16 carbon atoms (more preferably an aromatic ring having 6 to 12 carbon atoms, and particularly preferably an aromatic ring having 6 to 10 carbon atoms).

[0142] Ar, as a general formula BI 1 Ar 2 and Ar 3 Specific examples of aromatic rings include: a benzene ring in a monocyclic system; a biphenyl ring in a bicyclic system; a naphthalene ring in a fused bicyclic system; a terphenyl ring (m-terphenyl, o-terphenyl, or p-terphenyl) in a tricyclic system; an acenaphthene ring, fluorene ring, phenaene ring, and phenanthrene ring in a fused tricyclic system; a benzo[a]phenanthrene ring, pyrene ring, and benzo[a]tetraphenyl ring in a fused tetracyclic system; and a perylene ring and benzo[a]pentaphenyl ring in a fused pentacyclic system.

[0143] Ar, as a general formula BI 1 Ar 2 and Ar 3 The heteroaromatic ring can be, for example, a heteroaromatic ring having 2 to 30 carbon atoms, preferably a heteroaromatic ring having 2 to 25 carbon atoms (more preferably a heteroaromatic ring having 2 to 20 carbon atoms, even more preferably a heteroaromatic ring having 2 to 15 carbon atoms, particularly preferably a heteroaromatic ring having 2 to 10 carbon atoms). Furthermore, Ar, as a general formula BI... 1 Ar 2 and Ar 3 The heterocyclic ring can be, for example, a heterocyclic ring containing one to five heteroatoms selected from oxygen, sulfur, and nitrogen as cyclic atoms in addition to carbon.

[0144] Ar, as a general formula BI 1 Ar 2 and Ar 3Examples of heteroaromatic rings include pyrrole rings, oxazole rings, isoxazole rings, thiazole rings, isothiazole rings, imidazole rings, oxadiazole rings, thiadiazole rings, triazole rings, tetraazole rings, pyrazole rings, pyridine rings, pyrimidine rings, pyridazine rings, pyrazine rings, triazine rings, indole rings, isoindole rings, 1H-indazole rings, benzimidazole rings, benzoxazole rings, benzothiazole rings, 1H-benzotriazole rings, quinoline rings, isoquinoline rings, cyclophosphine rings, quinazolinite rings, quinoxaline rings, phthalazine rings, naphthidine rings, purine rings, pteridine rings, carbazole rings, acridine rings, and phenoxathiene rings. (ring), phenoxazine ring, phenothiazine ring, phenazine ring, indoleazine ring, furan ring, benzofuran ring, isobenzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, dibenzothiophene ring, furazine ring, oxadiazole ring, and thiathracene ring.

[0145] Ar, as a general formula BI 1 Ar 2 and Ar 3 At least one hydrogen atom in the aforementioned aromatic or heteroaromatic ring may be replaced by one or more substituents R. a replace,

[0146] Among them, R a Each time it appears, it can be independently selected from the group consisting of: hydrogen; deuterium; N(R) 5 )2; OR 5 ;SR 5 ;Si(R) 5 )3; CF3; CN; Halogen; C1-C 40 Alkyl groups may optionally be substituted with one or more substituents R. 5 And wherein, one or more non-adjacent CH2 groups are 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, SO2, NR 5 O, S or CONR 5 Replacement; C1-C 40 Thioalkoxy groups may optionally be substituted with one or more substituents R. 5 And wherein, one or more non-adjacent CH2 groups are 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, SO2, NR 5 O, S or CONR 5 Replacement; C6-C 60 The aryl group may optionally be substituted with one or more substituents R. 5 ; and C3-C 57 Heteroaryl groups may optionally be substituted with one or more substituents R. 5 ;

[0147] R 5 Each time it appears, it can be independently selected from the group consisting of: hydrogen; deuterium; N(R) 6 )2; OR 6 ;SR 6 ;Si(R) 6 )3; CF3; CN; F; C1-C 40 Alkyl groups may optionally be substituted with one or more substituents R. 6 And wherein, one or more non-adjacent CH2 groups are optionally R 6 C = CR 6 C≡C, Si(R) 6 )2、Ge(R 6 )2、Sn(R 6 )2. C=O, C=S, C=Se, C=NR 6 、P(=O)(R 6 SO, SO2, NR 6 O, S or CONR 6 Replacement; C6-C 60 The aryl group may optionally be substituted with one or more substituents R. 6 ; and C3-C 57 Heteroaryl groups may optionally be substituted with one or more substituents R. 6 ;

[0148] R 6 Each occurrence may be independently selected from the group consisting of: hydrogen; deuterium; OPh; CF3; CN; F; C1-C5 alkyl, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 alkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 thioalkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C6-C 18 The aryl group may optionally be replaced by one or more C1-C5 alkyl substituents; C3-C17 Heteroaryl groups may optionally be 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 (C6-C) 18 Aryl).

[0149] Examples of compounds represented by formula BI include compounds represented by the following general formulas B-II, B-III, or B-IV:

[0150]

[0151] in,

[0152] Y 1 Y 2 and Y 3 Each occurrence is independently selected from the group consisting of: NR'; O; C(R')2; S; or Si(R')2; wherein each R' is independently selected from the group consisting of: C1-C5 alkyl, optionally substituted with one or more substituents R. 6S C6-C 60 aryl, optionally substituted with one or more substituents R 6S ; and C3-C 57 Heteroaryl, optionally substituted with one or more substituents R 6S ;

[0153] R 6S Each time it appears, it is independently selected from the group consisting of: hydrogen; deuterium; OPh; CF3; CN; F; C1-C5 alkyl, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 alkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C1-C5 thioalkoxy, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C2-C5 alkenyl, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C2-C5 alkynyl, wherein optionally one or more hydrogen atoms are independently substituted by deuterium, CN, CF3 or F; C6-C 18 Aryl group, optionally substituted with one or more C1-C5 alkyl substituents; C3-C 17 Heteroaryl groups, 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 (C6-C) 18 Aryl).

[0154] Substituent R a R 5 R 6 , R' or R 6S They can optionally be independently of each other with one or more substituents R. a R 5 R 6 , R' or R 6S And / or aromatic rings or heteroaromatic rings Ar 1 Ar 2 and Ar 3 Forming monocyclic or polycyclic aliphatic, aromatic, heteroaromatic and / or benzo[a] fused ring systems.

[0155] In one embodiment, the compound represented by formula BI includes compounds represented by formulas B-III-1, B-III-2, B-III-3, B-IV-1, B-IV-2, and B-IV-3.

[0156]

[0157] The structure described above may optionally be replaced by one or more substituents, which may optionally additionally be rings.

[0158] In a preferred embodiment, the small FWHM emitter S B It includes or is composed of polycyclic aromatic compounds.

[0159] In one embodiment of the invention, the small FWHM emitter S B It is a near-range charge-transfer (NRCT) emitter. According to the invention, the NRCT emitter exhibits a delayed component in the time-resolved photoluminescence spectrum and demonstrates near-range HOMO-LUMO separation, as described by Hatakeyama et al. (Advanced Materials, 2016, 28(14):2777-2781, DOI:10.1002 / adma.201505491). In some embodiments, the NRCT emitter is a TADF material.

[0160] Examples of compounds represented by formula BI include structures containing the following:

[0161]

[0162]

[0163] In a preferred embodiment, the small FWHM emitter S B It is a green boron-containing NRCT emitter selected from the following group:

[0164]

[0165] Those skilled in the art will note that the light-emitting layer B is typically incorporated into the organic electroluminescent device of the present invention. 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.

[0166] Preferably, the anode layer A comprises at least one 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 mixtures of two or more thereof.

[0167] Preferably, the cathode layer C contains at least one 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 or alloys thereof of two or more thereof.

[0168] Preferably, the light-emitting layer B is located between the anode layer A and the cathode layer C. Therefore, it is generally preferred to be ABC. This, of course, does not preclude the existence of one or more alternative layers. These can be present on each side of A, B, and / or C.

[0169] In a preferred embodiment, the organic electroluminescent device includes at least the following layer:

[0170] A) Anode layer A, comprising at least one 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 mixtures of two or more thereof.

[0171] B) Light-emitting layer B; and

[0172] C) The cathode layer C comprises at least one 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 or alloys thereof of two or more thereof.

[0173] The light-emitting layer B is located between the anode layer A and the cathode layer C.

[0174] In one embodiment, when the organic electroluminescent device is an OLED, it may optionally include the following layer structure:

[0175] A) Anode layer A, exemplary comprising indium tin oxide (ITO);

[0176] HTL (Hole Transport Layer);

[0177] B) The light-emitting layer B according to the invention as described herein;

[0178] ETL (Electronic Transport Layer); and

[0179] C) Cathode layer, exemplarily comprising Al, Ca and / or Mg.

[0180] Preferably, the order of the layers here is A-HTL-B-ETL-C.

[0181] In addition, organic electroluminescent devices may optionally include one or more protective layers that protect the device from damaging exposure to harmful substances in the environment, including, for example, moisture, vapors and / or gases.

[0182] Preferably, the anode layer A is located on the surface of the substrate. The substrate can be formed of any material or combination of materials. Most commonly, a glass slide is used as the substrate. Alternatively, a thin metal layer (e.g., a copper, gold, silver, or aluminum film) or a plastic film or glass slide can be used. This allows for a higher degree of flexibility. The anode layer A is primarily composed of a material that allows for a (substantially) transparent film. Since at least one of the two electrodes should be (substantially) transparent to allow light emission from the OLED, either the anode layer A or the cathode layer C is transparent. Preferably, the anode layer A comprises a large amount of transparent conductive oxide (TCO), or is even composed of transparent conductive oxide (TCO).

[0183] Such an anode layer A may, by way of example, include indium tin oxide, zinc aluminum oxide, fluorine-doped 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.

[0184] Particularly preferably, the anode layer A is (essentially) made of indium tin oxide (ITO) (e.g., (InO3)). 0.9 (SnO2) 0.1The anode layer A, composed of a hole injection layer (HIL), can compensate for the roughness caused by the transparent conductive oxide (TCO). Furthermore, 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 facilitated. The hole injection layer (HIL) can include poly(3,4-ethylenedioxythiophene) (PEDOT), polystyrene sulfonate (PSS), MoO2, V2O5, CuPC, or CuI (specifically, 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 can exemplarily include 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'-spirodifluorene), DNTPD (N1,N1'-(biphenyl-4,4'-diyl)bis(N1-phenyl-N4,N4-di-m-tolylphenyl-1,4-diamine)), NPB ( N,N'-bis(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'-tetra(4-methoxyphenyl)benzidine), HAT-CN (1,4,5,8,9,12-hexaazatriphenylhexacarboxynitrile) and / or spiro-NPD (N,N'-diphenyl-N,N'-bis(1-naphthyl)-9,9'-spirodifluorene-2,7-diamine).

[0185] Adjacent to the anode layer A or the hole injection layer (HIL), a hole transport layer (HTL) is typically located. Any hole transport compound can be used here. Exemplarily, electron-rich heteroaromatic compounds such as triarylamines and / or carbazole 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 (used as the emission 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 tris(4-carbazole-9-ylphenyl)amine (TCTA), poly-TPD (poly(4-butylphenyl-diphenylamine)), α-NPD (2,2'-dimethyl-N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine), 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, NPN Star-shaped heterocycles of PB, MeO-TPD, HAT-CN, and / or triPcz (9,9'-diphenyl-6-(9-phenyl-9H-carbazol-3-yl)-9H,9'H-3,3'-bicarbazole). Additionally, the HTL may include a p-doped layer composed of inorganic or organic dopants in an organic hole transport matrix. Transition metal oxides such as vanadium oxide, molybdenum oxide, or tungsten oxide can be exemplarily used as inorganic dopants. Tetrafluorotetracyanoquinone dimethyl ether (F4-TCNQ), copper pentafluorobenzoate (Cu(I)pFBz), or transition metal complexes can be exemplarily used as organic dopants.

[0186] EBLs can include, for example, mCP (1,3-bis(carbazole-9-yl)benzene), 9,9'-bis([1,1'-biphenyl]-3-yl)-3,3'-bis-9H-carbazole (CAS 1352040-89-1); TCTA, 2-TNATA, mCBP (3,3-bis(9H-carbazole-9-yl)biphenyl), 9-[3-(dibenzofuran-2-yl)phenyl]-9H-carbazole, 9-[3-(dibenzothiophene-2-yl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzofuranyl)phenyl]-9H-carbazole, 9-[3,5-bis(2-dibenzothiophene)phenyl]-9H-carbazole, triPcz, CzSi (9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), 3',5'-bis(N-carbazole)-[1,1'-biphenyl]-2-carboxynitrile (DCPBN; CAS) 1918991-70-4), 3-(N-carbazolyl)-N-phenylcarbazolyl (NCNPC) and / or DCB (N,N'-dicarbazolyl-1,4-dimethylbenzene).

[0187] For the host compound, unless otherwise specified, the energy of the first excited triplet state T1 is determined by the starting point of the time-gated emission spectrum, preferably having a delay time of 1 ms and an integration time of 1 ms, measured at 77 K in a film of poly(methyl methacrylate) (PMMA) having 10 wt% of the host compound.

[0188] For small half-peak full width (FWHM) emitters, unless otherwise specified, the energy of the first excited triplet state T1 is determined by the starting point of a time-gated emission spectrum, typically with a delay time of 1 ms and an integration time of 1 ms, measured in a poly(methyl methacrylate) (PMMA) film containing 1 wt% of the small FWHM emitter, at 77 K.

[0189] For phosphorescent compounds, unless otherwise stated, the energy of the first excited triplet state T1 is determined by the starting point of a time-gated emission spectrum, typically having a delay time of 1 ms and an integration time of 1 ms at room temperature, measured in a poly(methyl methacrylate) (PMMA) film containing 10 wt% of the emitter (i.e., the phosphorescent compound).

[0190] The orbital and excited-state energies can be determined using experimental methods known to those skilled in the art. Experimentally, the highest occupied molecular orbital energy E... HOMO The lowest unoccupied molecular orbital energy E was determined by cyclic voltammetry with an accuracy of 0.1 eV using methods known to those skilled in the art. LUMO Calculated as E HOMO +E gap , of which Egap The following is determined:

[0191] For the host compound, unless otherwise specified, the starting point of the emission spectrum of the film containing 10 wt% of the host compound in poly(methyl methacrylate) (PMMA) (corresponding to the energy of the first excited singlet state S1) is used as E. gap .

[0192] For small half-peak full width at half-maximum (FWHM) emitters, unless otherwise specified, the starting point of the emission spectrum of a film containing 1 wt% of a small half-peak full width at half-maximum (FWHM) emitter in poly(methyl methacrylate) (PMMA) (corresponding to the energy of the first excited singlet state S1) is used as E. gap .

[0193] For organic phosphorescent emitters, unless otherwise specified, the starting point of the emission spectrum of a film containing 10 wt% organic phosphorescent emitter in poly(methyl methacrylate) (PMMA) (corresponding to the energy of the first excited singlet state S1) is used as E. gap .

[0194] In the electron transport layer (ETL), any electron transport agent can be used. Exemplarily, electron-depleted compounds such as benzimidazole, pyridine, triazole, oxadiazole (e.g., 1,3,4-oxadiazole), phosphine oxide, and sulfone can be used. Exemplarily, the electron transport agent ETM can also be a star-shaped heterocycle such as 1,3,5-tris(1-phenyl-1H-benzi[d]imidazol-2-yl)benzene (TPBi). ETMs can be exemplary, such as NBphen (2,9-bis(naphthyl-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (tris(8-hydroxyquinoline)aluminum), TSPO1 (diphenyl-4-triphenylsilylphenyl-phosphine oxide), BPyTP2 (2,7-bis(2,2'-bipyridin-5-yl)triphenylene), Sif87 (dibenzo[b,d]thiophene-2-yltriphenylsilane), Sif88 (dibenzo[b,d]thiophene-2-yldiphenylsilane), 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 can be doped with a material such as Liq (lithium 8-hydroxyquinoline). Optionally, a second electron transport layer may be located between the electron transport layer and the cathode layer C. The electron transport layer (ETL) may also block holes, or a hole blocking layer (HBL) may be introduced.

[0195] HBL can include, for example, HBM1: BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline = copper bath solution), BAlq (bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum), NBphen (2,9-bis(naphthyl-2-yl)-4,7-diphenyl-1,10-phenanthroline), Alq3 (tris(8-hydroxyquinoline)aluminum), TSPO1 (diphenyl-4-triphenylsilylphenylphosphine oxide), T2T (2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), T3T ( 2,4,6-Tris(terphenyl-3-yl)-1,3,5-triazine), TST(2,4,6-tris(9,9'-spirodifluorene-2-yl)-1,3,5-triazine), DTST(2,4-diphenyl-6-(3'-triphenylsilylphenyl)-1,3,5-triazine), DDTFB(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-9-yl)benzene).

[0196] Adjacent to the electron transport layer (ETL), a cathode layer C may be positioned. Exemplarily, the cathode layer C may comprise 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, or may be composed 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 be composed of a (substantially) opaque metal such as Mg, Ca, or Al. Optionally or additionally, the cathode layer C may also comprise graphite and / or carbon nanotubes (CNTs). Optionally, the cathode layer C may also be composed of nanoscale silver wires.

[0197] The OLED may further optionally include a protective layer (which may be designated as an electron injection layer (EIL)) between the electron transport layer (ETL) and the cathode layer C. This layer may include lithium fluoride, cesium fluoride, silver, Liq (lithium 8-hydroxyquinoline), Li2O, BaF2, MgO and / or NaF.

[0198] As used herein, unless otherwise defined in the specific context, the color of the emitted and / or absorbed light is specified as follows:

[0199] Purple: Wavelength range from >380nm to 420nm;

[0200] Deep blue: wavelength range from >420nm to 475nm;

[0201] Sky blue: wavelength range from >475nm to 500nm;

[0202] Green: Wavelength range >500nm to 560nm;

[0203] Yellow: Wavelength range >560nm to 580nm;

[0204] Orange: Wavelength range from >580nm to 620nm;

[0205] Red: Wavelength range from 620nm to 800nm.

[0206] Unless otherwise specified, for small FWHM emitters, this color refers to the maximum emission λ of a poly(methyl methacrylate) (PMMA) film containing 1 wt% of small FWHM emitters. max PMMA Unless otherwise specified, the color of the phosphorescent material and the host material refers to the maximum emission λ of the poly(methyl methacrylate) (PMMA) film, which contains 10% by weight of both the phosphorescent material and the host material. max PMMA .

[0207] Therefore, by way of example, the deep blue emitter has a maximum emission value λ in the range of 420 nm to 475 nm. max PMMA The sky-blue emitter has a maximum emission value λ in the range of 475 nm to 500 nm. max PMMA The green emitter has a maximum emission λ in the range of 500 nm to 560 nm. max PMMA The red emitter has a maximum emission λ in the range of 620 nm to 800 nm. max PMMA .

[0208] Therefore, another embodiment of the present invention relates to an OLED that has a density of 1000 cd / m². 2 It exhibits an external quantum efficiency greater than 10% (more preferably greater than 13%, more preferably greater than 15%, even more preferably greater than 18%, or even greater than 20%), and / or exhibits a maximum emission value between 490 nm and 600 nm (preferably between 500 nm and 580 nm, more preferably between 510 nm and 560 nm, even more preferably between 520 nm and 540 nm), and / or at a constant current density J0 = 15 mA / cm². 2 The LT95 value exhibits a value greater than 100h (preferably greater than 200h, more preferably greater than 400h, even more preferably greater than 750h, or even greater than 1000h).

[0209] Another embodiment of the present invention relates to an OLED that emits light at different color points. According to the present invention, the OLED emits light having a narrow emission band (small half-peak full width (FWHM)). In a preferred embodiment, the OLED according to the invention emits light with an FWHM having a main emission peak below 0.25 eV (more preferably below 0.20 eV, even more preferably below 0.15 eV, or even below 0.13 eV).

[0210] Another embodiment of the invention relates to an OLED that emits light having CIEx and CIEy color coordinates (CIEx = 0.170, CIEy = 0.797) (these CIEx and CIEy color coordinates (CIEx = 0.170, CIEy = 0.797) are close to the CIEx (= 0.170), CIEy (= 0.797) color coordinates of the primary color green as defined by ITU-R Recommendation BT.2020 (Rec.2020), and is therefore suitable for use in ultra-high definition (UHD) displays (e.g., UHD-TV). In this context, the term "close to" refers to the range of CIEx and CIEy coordinates provided at the end of this paragraph. In commercial applications, top-emitting devices (with a transparent top electrode) are typically used, while the test device as used throughout this application represents a bottom-emitting device (with a transparent bottom electrode and substrate). Therefore, another aspect of the present invention relates to an OLED whose emission exhibits CIEx color coordinates between 0.15 and 0.45 (preferably between 0.15 and 0.35, more preferably between 0.15 and 0.30, or even more preferably between 0.15 and 0.25, or even more preferably between 0.15 and 0.20), and / or CIEy color coordinates between 0.60 and 0.92 (preferably between 0.65 and 0.90, more preferably between 0.70 and 0.88, or even more preferably between 0.75 and 0.86, or even more preferably between 0.79 and 0.84).

[0211] Another aspect of the invention relates to an OLED that emits light having CIEx and CIEy color coordinates (CIEx = 0.265, CIEy = 0.65) (which are close to the CIEx (= 0.265, CIEy = 0.65) and CIEy (= 0.65) color coordinates of the primary color green as defined by DCIP3). In this context, the term "close to" refers to the range of CIEx and CIEy coordinates provided at the end of this paragraph. In commercial applications, top-emitting (top electrode is transparent) devices are typically used, while the test device as used throughout this application represents a bottom-emitting device (bottom electrode and substrate are transparent). Therefore, another aspect of the present invention relates to an OLED whose bottom emission exhibits CIEx color coordinates between 0.2 and 0.45 (preferably between 0.2 and 0.35, or more preferably between 0.2 and 0.30, or even more preferably between 0.24 and 0.28, or even more preferably between 0.25 and 0.27), and / or CIEy color coordinates between 0.60 and 0.9 (preferably between 0.6 and 0.8, more preferably between 0.60 and 0.70, or even more preferably between 0.62 and 0.68, or even more preferably between 0.64 and 0.66).

[0212] As used throughout this application, the terms "aryl" and "aromatic" may be understood in the broadest sense as any monocyclic, bicyclic, or polycyclic aromatic moiety. In one embodiment, the aryl residue may be C6 to C6. 18 Aryl residue. In one embodiment, the aryl residue may be C6 to C6. 14 aryl residues or C6 to C 10 Aryl residues. A more specific definition is provided in the context of the corresponding compounds above. Unless otherwise stated, aryl groups may optionally be substituted with one or more substituents, which are further exemplified throughout this application. Thus, the term "anelyl" refers to a divalent residue having two binding sites with other molecular structures and thus serving as a linker structure. As used throughout this application, the terms "heteroaryl" and "heteroaromatic" can be understood in the broadest sense as any monocyclic, bicyclic, or polycyclic heteroaromatic moiety comprising at least one heteroatom (specifically, one to three heteroatoms per aromatic ring). In one embodiment, the heteroaryl residue may be C2 to C3. 17 Aryl residues. In one embodiment, heteroaryl residues may be C2 to C3. 15 aryl residues or C2 to C 13 Aryl residues.

[0213] Exemplary examples include pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, and pyrimidine. Unless otherwise stated, the heteroaryl group may optionally be substituted with one or more substituents, which are further exemplified throughout this application. Therefore, the term "hybrid aryl" refers to a divalent residue having two binding sites with other molecular structures and thus serving as a linker structure.

[0214] Unless otherwise specified, percentages refer to weight percentages ((weight / weight), (w / w), weight %).

[0215] As used throughout this application, the term "alkyl" may be understood in the broadest sense as both straight-chain and branched alkyl residues. Preferably, an alkyl residue is an alkyl residue containing one to fifteen carbon atoms. Exemplarily, an alkyl residue may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, etc. Unless otherwise stated, an alkyl group may optionally be substituted with one or more substituents, which are further exemplified throughout this application. Thus, the term "alkylene" refers to a divalent residue having two binding sites with other molecular structures and thereby serving as a linker structure.

[0216] Unless otherwise specified, as used herein, specifically in the context of aryl, arylene, heteroaryl, alkyl, etc., the term "substituted" may be understood in the broadest sense. Preferably, such substitution refers to a selection from C1-C1 compounds. 20 Alkyl, C7-C 19 Alkyl and C6-C 18 The residues in the group consisting of aryl groups. Therefore, preferably, there is no charged moiety in this substitution (more preferably, no functional group).

[0217] It should be noted that hydrogen can be replaced by deuterium each time it appears.

[0218] Unless otherwise stated, any layer in the various embodiments can be deposited by any suitable method. In the context of this invention, the layer including the light-emitting layer B can optionally be prepared by means of liquid processing (also specified as "film processing," "fluid processing," "solution processing," or "solvent processing"). This means that the components included in the respective layer are applied in liquid form to the surface of a portion of the device. Preferably, in the context of this invention, the layer including the light-emitting layer B can be prepared by means of spin coating. This method, known to those skilled in the art, allows for the acquisition of thin and (substantially) uniform layers.

[0219] Alternatively, the layer including the light-emitting layer B, within the context of this invention, can be prepared by other liquid-based processing methods (such as casting (e.g., drop casting)) as well as roll coating and printing methods (e.g., inkjet printing, gravure printing, blade coating). This can optionally be carried out in an inert atmosphere (e.g., in a nitrogen atmosphere).

[0220] In another preferred embodiment, the layer in the context of this invention can 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 deposition by organic vapor jet printing (OVJP)).

[0221] When the layer is prepared by means of liquid processing, the components of the layer include (i.e., for the light-emitting layer B of the present invention, at least one host compound H) P And typically at least one phosphorescent material E B At least a small half-peak full width at half maximum (FWHM) emitter S B And optionally one or more other host compounds H N The solution 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-methylpyrrolidone, ethoxyethanol, xylene, toluene, anisole, phenethyl ether, acetonitrile, tetrahydrothiophene, benzyl nitrile, 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 liquid form, the layer may subsequently (exemplarily, under ambient conditions, at elevated temperatures (e.g., about 50°C or about 60°C), or under reduced pressure) be dried and / or hardened by any means in the art.

[0222] Optionally, the organic light-emitting device (e.g., OLED) can be, exemplarily, a substantially white organic light-emitting device or a blue organic light-emitting device. Exemplarily, such a white organic light-emitting device may include at least one (deep) blue emitting compound and one or more emitting compounds that emit green light (e.g., phosphorescent material E). B or small FWHM emitter S B And / or one or more emitter compounds that emit red light. Then, energy transmittance may optionally exist between the two or more compounds as described above.

[0223] Organic electroluminescent devices, as a whole, can also be formed into thin layers with a thickness of no more than 5 mm, no more than 2 mm, no more than 1 mm, no more than 0.5 mm, no more than 0.25 mm, no more than 100 μm, or no more than 10 μm.

[0224] Organic light-emitting devices (e.g., OLEDs) can be small in size (e.g., having a diameter of no more than 5 mm). 2 or even no more than 1mm 2 (Surface area), medium size (e.g., with a surface area of ​​0.5 cm) 2 Up to 20cm 2 (Surface within the range) or large size (e.g., with a diameter greater than 20 cm) 2 (The surface of the surface). The organic electroluminescent devices (e.g., OLEDs) according to the invention can be optionally used to produce screens as large-area lighting devices, as luminescent wallpaper, luminescent window frames or glass, luminescent labels, luminescent posters, or flexible screens or displays. In addition to common applications, organic electroluminescent devices (e.g., OLEDs) can also be used exemplary as luminescent films, "smart packaging" labels, or innovative design elements. Furthermore, they can be used for cell detection and examination (e.g., as biomarkers).

[0225] One of the primary purposes of organic electroluminescent devices is to generate light. Therefore, the present invention further relates to a method for generating light within a desired wavelength range, the method comprising the step of providing an organic electroluminescent device according to any of the present invention.

[0226] Therefore, another aspect of the present invention relates to a method for generating light within a desired wavelength range, the method comprising the following steps:

[0227] (i) providing an organic electroluminescent device according to the present invention; and

[0228] (ii) Apply current to the organic electroluminescent device.

[0229] Another aspect of the present invention relates to a process for manufacturing an organic electroluminescent device by assembling the aforementioned components. The present invention also relates to a method for generating green light (specifically, by using the organic electroluminescent device).

[0230] Examples and claims further illustrate the invention.

[0231] Example

[0232] Cyclic voltammetry

[0233] The measurement was performed in dichloromethane or a suitable solvent and a suitable supporting electrolyte (e.g., 0.1 mol / L tetrabutylammonium hexafluorophosphate) with a concentration of 10. -3Cyclic voltammograms of solutions containing mol / L organic molecules. Measurements were performed at room temperature under a nitrogen atmosphere using a three-electrode assembly (working and counter electrodes: Pt lines, reference electrode: Pt lines) and using FeCp2 / FeCp2. + Calibration was performed using ferrocene as an internal standard. HOMO data were corrected for SCE using ferrocene as an internal standard.

[0234] Density functional theory calculations

[0235] The molecular structure was optimized using the BP86 functional and the resolution of identity approach (RI). Excitation energies were calculated using the BP86-optimized structure via time-dependent DFT (TD-DFT). Orbital and excited-state energies were calculated using the B3LYP functional. The Def2-SVP basis set and an m4 grid were used for numerical integration. The Turbomole package was used for all calculations.

[0236] Optical physical measurement

[0237] Sample pretreatment: spin coating.

[0238] Instruments: Spin150, SPS euro.

[0239] The sample concentration was 10 mg / mL, and it was dissolved in a suitable solvent.

[0240] Program: 1) 3 seconds at 400 U / min. 2) 20 seconds at 1000 Upm / s at 1000 U / min. 3) 10 seconds at 4000 Upm / s at 1000 U / min. After coating, dry the film at 70°C for 1 minute.

[0241] Photoluminescence spectroscopy and TCSPC (Time-Correlated Single Photon Counting)

[0242] Steady-state emission spectra were recorded using a Horiba Scientific Modell FluoroMax-4 equipped with a 150W xenon arc lamp, excitation and emission monochromators, a Hamamatsu R928 photomultiplier tube, and a time-correlated single-photon counting option. Emission and excitation spectra were corrected using standard calibration fitting.

[0243] The excited-state lifetime was determined using the same system as the FM-2013 device and the Horiba Yvon TCSPC hub, employing the TCSPC method.

[0244] Excitation source:

[0245] Nano LED 370 (wavelength: 371nm, pulse duration: 1.1ns)

[0246] Nano LED 290 (wavelength: 294nm, pulse duration: <1ns)

[0247] Spectral LED 310 (wavelength: 314nm)

[0248] Spectral LED 355 (wavelength: 355nm).

[0249] Perform data analysis (exponential fit) using the DataStation and DAS6 software suite. Specify the fit using the chi-square test.

[0250] Photoluminescence quantum yield measurement

[0251] For photoluminescent quantum yield (PLQY) measurements, an absolute PL quantum yield measurement system (Hamamatsu Photonics) C9920-03G was used. Quantum yield and CIE coordinates were determined using software version U6039-05 3.6.0.

[0252] The maximum emission value is given in nm, the quantum yield Φ is given in % and the CIE coordinates are given as x and y values.

[0253] PLQY is determined using the following protocol:

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

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

[0256] 3) Measurement

[0257] For the sample, the quantum yield of the solution or membrane is measured under a nitrogen atmosphere. The yield is calculated using the equation:

[0258]

[0259] Where, n 光子 Indicates photon count, and Int. is intensity.

[0260] Fabrication and characterization of organic electroluminescent devices

[0261] OLED devices comprising the organic molecules according to the invention can be fabricated via vacuum deposition. If the layer contains more than one compound, the weight percentage of one or more compounds is given as %. The total weight percentage value totals 100%, so if no value is given, the fraction of the compound is equal to the difference between the given value and 100%.

[0262] The not-fully-optimized OLED was characterized using standard methods and measurements of electroluminescence spectra. The external quantum efficiency (in percentage) depends on the intensity and is calculated using light and current detected by a photodiode.

[0263] OLED device lifetime is extracted from the change in brightness during operation at a constant current density. The LT50 value corresponds to the time when the measured brightness decreases to 50% of the initial brightness, similarly, LT80 corresponds to the time when the measured brightness decreases to 80% of the initial brightness, LT95 corresponds to the time when the measured brightness decreases to 95% of the initial brightness, and so on.

[0264] (For example, by applying an increased current density) Perform accelerated lifetime measurements. Exemplarily, 500 cd / m² is determined using the following equation. 2 The following LT80 value:

[0265]

[0266] Where L0 represents the initial brightness at the applied current density.

[0267] The values ​​correspond to the average of several (typically two to eight) pixels, giving the standard deviation among these pixels. The figure illustrates the data series for a single OLED pixel.

[0268] Experimental results

[0269]

[0270]

[0271] Table 1. Properties of materials.

[0272]

[0273]

[0274] Among them, LUMO CV It is the energy of the lowest unoccupied molecular orbital determined by cyclic voltammetry. a The emission spectrum was recorded using a solution of Ir(ppy)3 in chloroform. b Emission spectrum via E B -I was recorded in a 0.001 mg / mL solution in dichloromethane.

[0275] Table 2. Setting of example organic light-emitting device (OLED) H and comparative examples OLED D and P.

[0276]

[0277] To evaluate the results of the invention, a comparative experiment was conducted in which only the composition of the emission layer (6) was changed. Additionally, in the comparative experiment, H... P and H N The proportion remains constant.

[0278] Table 3. Results for emitter S1

[0279] Emitting layer settings (percentage refers to weight percentage):

[0280]

[0281] Wherein, mCBP is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S1 is used as S B The percentage is a weight percentage.

[0282] Table 4. Device Results

[0283]

[0284] Table 5. Results regarding emitter S1 (II)

[0285] Emitting layer settings (percentage refers to weight percentage):

[0286]

[0287] Wherein, mCBP is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S1 is used as S B The percentage is a weight percentage.

[0288] Table 6. Device Results

[0289]

[0290] Table 7. Results for emitter S1 (III)

[0291] Emitting layer settings (percentage refers to weight percentage):

[0292]

[0293]

[0294] Among them, the main body P1 is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S1 is used as SB The percentage is a weight percentage.

[0295] Table 8. Device Results

[0296]

[0297] Table 9. Results for emitter S2

[0298] Emitting layer settings (percentage refers to weight percentage):

[0299]

[0300] Wherein, mCBP is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S2 is used as S B The percentage is a weight percentage.

[0301] Table 10. Device Results

[0302]

[0303] Table 11. Results regarding emitter S2 (II)

[0304] Emitting layer settings (percentage refers to weight percentage):

[0305]

[0306]

[0307] Among them, the main body P1 is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S2 is used as S B The percentage is a weight percentage.

[0308] Table 12. Device Results

[0309]

[0310] For using mCBP as H P And 7% Ir(ppy)3 as E BFor all H-type devices, a 16% increase in relative lifetime was observed for emitter S1 (from 1.00 to 1.16), and a 140% increase in relative lifetime was observed for emitter S2 (from 1.00 to 2.40), while efficiency remained almost constant (at approximately EQE = 23%). For emitter S1, FWHM decreased by 33% (from 0.30 eV to 0.20 eV), and for emitter S2, FWHM decreased by 46% (from 0.30 eV to 0.16 eV). For green applications, for emitter S1, the color point improved towards CIEx = 0.26 and CIEy = 0.66, and for emitter S2, the color point improved towards CIEx = 0.32 and CIEy = 0.65.

[0311] For using subject P1 as H P And 7% Ir(ppy)3 as E B For all H-type devices, a 10% increase in relative lifetime was observed for emitter S1 (from 1.00 to 1.10), and a 60% increase in relative lifetime was observed for emitter S2 (from 1.00 to 1.60), while efficiency remained almost constant (at almost EQE = 24%). For emitter S1, FWHM decreased by 30% (from 0.30 to 0.21), and for emitter S2, FWHM decreased by 45% (from 0.31 to 0.17). For green applications, for emitter S1, the color point improved towards CIEx = 0.26 and CIEy = 0.66, and for emitter S2, the color point improved towards CIEx = 0.32 and CIEy = 0.65.

[0312] For using the main body mCBP as H P And 10% Ir(ppy)3 as E B And the emitter S1 as S B For all H-type devices, a 44% increase in relative lifetime can be observed (from 1.00 to 1.44), while efficiency remains almost constant (at almost EQE = 22%), FWHM is reduced by 33% (from 0.30 to 0.20), and for green applications, the color point improves toward CIEx = 0.26 and CIEy = 0.66.

[0313] Table 13. Results for emitter S2 (III)

[0314] Emitting layer settings (percentage refers to weight percentage):

[0315]

[0316]

[0317] Among them, the main body P2 is used as HP The main body N2 is used as H N E B -I is used as E B The emitter S2 is used as S B The percentage is a weight percentage.

[0318] Table 14. Device Results.

[0319]

[0320] Comparing P-type and H-type devices, for devices using the main body P2 as H... P The main body N2 serves as H N and 7% E B -I as E B And the launcher S2 as S B The H-type device exhibits a 59% increase in relative lifetime (from 1.00 to 1.59), an improvement in efficiency (from 23.2% to 26.1%), a 45% reduction in FWHM (from 0.29 eV to 0.16 eV), and enables green applications for color dots.

[0321] Based on the individual LT95 lifetimes measured at 1200 nits, the relative lifetimes for all device experiments were determined.

[0322] Results regarding emitter S3

[0323]

[0324] Table 15. Properties of emitter S3.

[0325]

[0326] Among them, LUMO CV It is the energy of the lowest unoccupied molecular orbital determined by cyclic voltammetry.

[0327] Table 16. Results for emitter S3

[0328] Emitting layer settings (percentage refers to weight percentage):

[0329]

[0330] Among them, the main body P1 is used as H P The main body N1 is used as H N Ir(ppy)3 is used as E B The emitter S3 is used as S B The percentage is a weight percentage.

[0331] Table 17. Device Results

[0332]

[0333] Comparing P-type and H-type devices, for devices using the main body P1 as H... P And 7% Ir(ppy)3 as E B And the launcher S3 as S B The H-type device exhibits a 34% increase in relative lifetime (from 1.00 to 1.34), an improvement in efficiency (from 23.2% to 24.7%), a 42% reduction in FWHM (from 0.31 eV to 0.18 eV), and enables green applications for color dots.

[0334] Based on the individual LT95 lifetimes measured at 1200 nits, the relative lifetimes for all device experiments were determined.

Claims

1. An organic electroluminescent device, the organic electroluminescent device comprising an emissive layer B, the emissive layer B comprising: (i) Main material H P It has the lowest excited singlet state energy level S1 P and the lowest excited triplet energy level T1 P Possessing energy E HOMO (H P The highest occupied molecular orbital (HOMO) of H P ) and possessing energy E LUMO (H P The lowest unoccupied molecular orbital LUMO (H) P ); (ii) Phosphorescent materials E B It has the lowest excited singlet state energy level S1 E and the lowest excited triplet energy level T1 E Possessing energy E HOMO (E B The highest occupied molecular orbital (HOMO) of ) B ) and possessing energy E LUMO (E B The lowest unoccupied molecular orbital LUMO (E) B ); as well as (iii) Small half-peak full-width emitter S B It has the lowest excited singlet state energy level S1 S and the lowest excited triplet energy level T1 S Possessing energy E HOMO (S B The highest occupied molecular orbital (HOMO) of ) B ) and possessing energy E LUMO (S B The lowest unoccupied molecular orbital (LUMO) of ) B ), Among them, E B Transfer energy to S B And S B It emits light with a maximum emission value between 500nm and 560nm. Among them, the relationships represented by the following equations (1) to (4) apply: T1 E >S1 S (1) T1 P >T1 S (2) T1 P >T1 E (3) T1 P >S1 E (4), and Among them, the small half-peak full-width emitter S B The feature is that the small half-peak full-width emitter S B It has an emission spectrum with a full width at half maximum (FWHM) of less than or equal to 0.25 eV in poly(methyl methacrylate).

2. The organic electroluminescent device according to claim 1, wherein, The organic electroluminescent device exhibits a maximum emission λ of 500 nm to 560 nm. max (D) 3. The organic electroluminescent device according to claim 1, wherein, The small half-peak full-width emitter S B It emits light with a maximum emission value between 510nm and 550nm.

4. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The organic electroluminescent device exhibits a maximum emission λ from 510 nm to 550 nm. max (D) 5. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The light-emitting layer B additionally includes: (iv) Main material H N It has the lowest excited singlet state energy level S1 N The lowest excited triplet energy level T1 N Possessing energy E HOMO (H N The highest occupied molecular orbital (HOMO) of H N ) and possessing energy E LUMO (H N The lowest unoccupied molecular orbital LUMO (H) N ); Among them, the relationships represented by the following equations (2N), (3N), and (4N) apply: T1 N >T1 S (2N) T1 N >T1 E (3N) T1 N >S1 E (4N), Furthermore, the relationships expressed by equations (5) to (11) below apply: E LUMO (H P )>E LUMO (S B )(5) AND LUMO (H P )>E LUMO (AND B )(6) E HOMO (H P )<E HOMO (E B )(7) E LUMO (H N )<E LUMO (S B )(8) E HOMO (H N )<E HOMO (S B )(9) E LUMO (H N )<E LUMO (E B )(10) E HOMO (H N )<E HOMO (E B )(11)。 6. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The small half-peak full-width emitter S B Selected from the group consisting of fluorescent emitters and thermally activated delayed fluorescent emitters.

7. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The small half-peak full-width emitter S B It is a boron-based material.

8. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The small half-peak full-width emitter S B The feature is that the small half-peak full-width emitter S B It has a ΔE of less than 0.4 eV. ST The value, the ΔE ST Value and S1 S With T1 S The energy difference between them corresponds.

9. The organic electroluminescent device according to any one of claims 1 to 3, wherein, The phosphorescent material E B Includes or is composed of the structure of Formula I. Formula I, in, M is selected from the group consisting of Ir, Pt, Au, Eu, Ru, Re, Ag and Cu; n is an integer from 1 to 3. Both X and Y are independently bidentate monoanion ligands.

10. The organic electroluminescent device according to claim 5, wherein, The light-emitting layer B includes: (i) 22% to 70% by weight of the said bulk material H P ; (ii) 0% to 70% by weight of the main material H N ; (iii) 5% to 10% by weight of the phosphorescent material E B ;and (iv) 1% to 5% by weight of the small half-peak full-width emitter S B ; and optionally (v) 0% to 72% by weight of one or more solvents.

11. The organic electroluminescent device according to claim 5, wherein, The light-emitting layer B includes: (i) 10% to 30% by weight of the main material H P ; (ii) 40% to 74% by weight of the said bulk material H N ; (iii) 15% to 30% by weight of the phosphorescent material E B ;and (iv) 1% to 5% by weight of the small half-peak full-width emitter S B ; and optionally (v) 0% to 34% by weight of one or more solvents.

12. A method for generating green light at wavelengths from 500 nm to 560 nm, the method comprising the steps of: (i) Providing an organic electroluminescent device according to any one of claims 1 to 11; and (ii) Apply current to the organic electroluminescent device.

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