Organic light emitting diode

Abstract

Provided is an organic light-emitting diode including a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode, the light-emitting layer including a composite light-emitting compound designed according to the conditions described in the detailed description.

Description

Technical Field

[0001] The present invention relates to an organic light emitting diode comprising an organic light emitting substance with a long lifespan. Background Art

[0002] Organic light-emitting diodes (OLEDs) are devices in which holes injected from the anode and electrons injected from the cathode combine in the light-emitting layer through a charge transport layer to form excitons, which then emit light. They were first reported by CW Tang in 1987 in Appl. Phys. Lett. 51, 913. At that time, the light-emitting layer consisted of a single substance, Alq3. However, in 1989, in J. Appl. Phys., Vol. 65, 3610, they reported that by doping Alq3 with small amounts of the red-emitting compound DCM and the green-emitting compound Coumarine 540, the emission wavelength was adjusted and efficiency was improved. Summary of the Invention

[0003] Technical issues

[0004] An object of the present invention is to provide an organic light emitting diode that can minimize the brightness of light even when driven for a long time by improving the light emission stability of the light emitting body.

[0005] The purpose of the present invention is not limited to the above-mentioned purpose, and other purposes and advantages not mentioned in the present invention can be understood through the following description and can be more clearly understood through the embodiments of the present invention. In addition, it is easy to understand that the purposes and advantages of the present invention can be achieved by the means described in the claims and their combinations.

[0006] Technical Solution

[0007] In one embodiment of the present invention,

[0008] An organic light emitting diode is provided, comprising a first electrode, a second electrode, and a light emitting layer located between the first electrode and the second electrode.

[0009] The light-emitting layer comprises a composite light-emitting compound and a host compound,

[0010] The composite light-emitting compound comprises a hole regulating part, a connecting part and a light-emitting part,

[0011] The composite light-emitting compound comprises a connecting portion connecting the hole regulating portion and the light-emitting portion via a spiro bond,

[0012] The hole regulating part is a substituted or unsubstituted C6-50 aromatic ring or C5-50 aromatic hetero-condensed ring, or an organometallic compound derived from the ring and metal.

[0013] the hole modulating moiety comprises at least one atom having an unshared electron pair contained in the HOMO or LUMO wave function of the hole modulating moiety,

[0014] The HOMO-LUMO energy gap of the hole adjustment part is greater than the maximum emission wavelength energy of the light emitting part,

[0015] The HOMO energy level of the hole modulating moiety is higher than the HOMO energy level of the host compound.

[0016] Effects of the Invention

[0017] The organic light emitting diode comprising the composite light emitting compound of the present invention improves the light emitting stability of the device, thereby minimizing the brightness during long-term driving.

[0018] In addition to the above effects, specific embodiments will be described below in combination with the specific effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The HOMO and LUMO energy levels of a conventional host compound and a dopant compound and the HOMO and LUMO energy levels of a host compound and a dopant compound to be achieved by the present invention are shown.

[0020] Figure 2 Graphs showing the light-emitting characteristics of devices 1 to 4.

[0021] Figure 3 is a graph showing the light-emitting characteristics of device 5 and device 6.

[0022] Figure 4 Graphs showing the lifetime characteristics of device 7 and device 8 are shown. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be implemented in various forms and is not limited to the embodiments described herein.

[0024] As used herein, the term "substituted" refers to the replacement of a hydrogen atom bonded to a carbon atom in a compound with another substituent. The position where the substitution occurs refers to the position where the hydrogen atom is replaced. The position is not limited, as long as the hydrogen at the position can be replaced by a substituent. When two or more substitutions occur, the two or more substituents may be the same or different.

[0025] In the present specification, unless otherwise mentioned, the substituent in the case of "substituted" may be selected from, for example, deuterium, C1-20 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 allyl, C1-30 alkoxy, halogen, cyano, carboxyl, carbonyl, amino, C1-30 alkylamino, C3-30 cycloalkylamino, C2-30 heterocycloalkylamino, nitro, C1-30 alkylsilyl, C3-30 cycloalkylsilyl, C2-30 heterocycloalkylsilyl, One of the group consisting of a C1-30 alkoxysilyl group, a C6-30 arylsilyl group, a C6-30 aryl group, a C6-30 arylamine group, a C2-30 heteroaryl group, a C6-30 arylphosphine oxide group, a C6-30 arylphosphino group, a C1-30 alkylphosphine oxide group, a C3-30 cycloalkylphosphine oxide group, a C2-30 heterocycloalkylphosphine oxide group, a C1-30 alkylsulfonyl group, a C3-30 cycloalkylsulfonyl group, a C2-30 heterocycloalkylsulfonyl group and combinations thereof, but not limited thereto.

[0026] In this specification, unless otherwise defined, "a combination thereof" in the definition of a substituent means the presence of two or more substituents, or two or more divalent substituents that are linked or condensed.

[0027] In the present specification, the case where two substituents are linked to form a ring includes the case where one of the two substituents is hydrogen and the linking occurs when the hydrogen is removed.

[0028] In the present specification, unless otherwise mentioned, an alkyl group includes a cycloalkyl group and a heterocycloalkyl group. In addition, for example, unless otherwise mentioned, an alkylamine includes a cycloalkylamine and a heterocycloalkylamine.

[0029] In this specification, unless otherwise defined, "hetero" means that a compound or substituent contains a heteroatom. The heteroatom refers to an atom other than carbon and hydrogen in the atoms forming the heterocyclic compound, and may be, for example, N, O, Si, Ge, S, P, B, Se, Te, etc., but is not limited thereto. When a compound or substituent contains two or more heteroatoms, they may contain the same or different heteroatoms, for example, one or more heteroatoms. For example, a heteroaryl group or a heterocycloalkyl group contains at least one heteroatom as a ring atom.

[0030] In the present specification, unless otherwise mentioned, a ring includes a fused ring.

[0031] In one embodiment of the present invention,

[0032] An organic light emitting diode (OLED) is provided, comprising a first electrode, a second electrode, and a light emitting layer located between the first electrode and the second electrode.

[0033] The light-emitting layer comprises a composite light-emitting compound and a host compound,

[0034] The composite light-emitting compound comprises a hole regulating part, a connecting part and a light-emitting part,

[0035] The composite light-emitting compound comprises a connecting portion connecting the hole regulating portion and the light-emitting portion via a spiro bond,

[0036] The hole regulating part is a substituted or unsubstituted C6-50 aromatic ring or C5-50 aromatic hetero-condensed ring, or an organometallic compound derived from the ring and metal.

[0037] the hole modulating moiety comprises at least one atom having an unshared electron pair contained in the HOMO or LUMO wave function of the hole modulating moiety,

[0038] The HOMO-LUMO energy gap of the hole adjustment part is greater than the maximum emission wavelength energy of the light emitting part,

[0039] The HOMO energy level of the hole modulating moiety is higher than the HOMO energy level of the host compound.

[0040] The organic light emitting diode utilizes the composite light emitting compound designed according to the above conditions to improve the light emitting stability of the device, thereby realizing an organic light emitting diode capable of reducing the brightness to the maximum extent even under long-term driving.

[0041] In addition to the wavelength and efficiency of organic light-emitting diodes (OLEDs), the dopant compound plays a crucial role in determining the device's brightness decay over time. This composite luminescent compound is designed and developed by improving the dopant compound's degradation mechanism and energy transfer process, enabling the device to exhibit stable brightness even under long-term operation.

[0042] The process in which electrons and holes injected into the light-emitting layer combine in the host compound in the light-emitting layer to form excitons and their energy is transferred to the dopant compound can be expressed by the light-based method (FRET, ResonanceEnergy transfer) and the electron-based method (Dexter Electron Transfer) of the following mathematical formula 2 are used to explain it.

[0043] FRET Resonance Energy transfer)

[0044] Mathematical formula 1

[0045]

[0046] Dexter Electron Transfer

[0047] Mathematical formula 2

[0048]

[0049] k ET : rate constant

[0050] r: distance between energy donor and energy acceptor

[0051] τ D : PL decay time of energy donor

[0052] κ: orientation factor

[0053] Q D : PL quantum efficiency of energy donor

[0054] N A : Avogadro's constant

[0055] n: refractive index

[0056] J: defined by the following mathematical formula 3.

[0057] Mathematical formula 3

[0058] J = ∫f D (λ)ε A (λ)λ 4 dλ

[0059] f D : Luminescence spectrum of energy donor

[0060] ε A : wavelength-dependent absorption coefficient of the energy acceptor

[0061] L: the sum of Van der Waals radii

[0062] λ: wavelength

[0063] Once the dopant compound receives energy from the host compound, it enters an excited state. This is the same state as when one of the two electrons in the dopant compound's highest occupied molecular orbital (HOMO) energy level moves to the lowest unoccupied molecular orbital (LUMO) energy level. The time required for an electron to transition from the LUMO energy level to the HOMO energy level and re-stabilize can range from a few nanoseconds to several milliseconds, depending on the electron's spin state. Considering that the vibrational motion of molecules takes place in the order of picoseconds, the excited dopant compound will continuously interact with surrounding molecules before being relaxed by light. This will form new energy levels, trigger chemical reactions, or decompose. This series of processes will accelerate the decrease in luminous intensity over the driving time of the organic light-emitting diode. High-efficiency light-emitting devices are achieved through the charge balance of holes and electrons, and the dopant compound will also affect the charge balance of holes and electrons and the distribution of excitons within the light-emitting layer.

[0064] The HOMO-LUMO energy gap energy of the dopant compound is always smaller than the HOMO-LUMO energy gap energy of the host compound, but the energy level position between the two substances is not always constant. Figure 1 In, E HOMO Indicates the HOMO energy level of each substance, E LUMO Indicates the LUMO energy level of each substance.

[0065] Type 1 is a type where the HOMO energy level of the dopant compound is higher than that of the host compound. The type is the same as that of the host compound and dopant compound. Holes are directly injected into the light-emitting layer through the hole transport layer, and electrons are injected into the light-emitting layer through the electron transport layer on the other side. Holes and electrons are injected into the light-emitting layer from a thickness of The holes are injected from both sides of the light-emitting layer, so the holes are trapped by the dopant compound before the two charges meet to form excitons.

[0066] When charges are trapped by a dopant compound, the ionized dopant compound becomes extremely unstable and seeks a stable path until an opposite charge arrives. It may interact with other excitons formed nearby, chemically react with surrounding compounds, or decompose. This series of processes accelerates the decrease in luminescence intensity over the operating time of the OLED.

[0067] Type 2 shows the HOMO energy levels of each moiety in a composite luminescent compound, in which a luminescent moiety and a hole modulating moiety are connected via a linker, and the HOMO energy level of the host compound. This composite luminescent compound is formed by connecting a hole modulating moiety to the luminescent compound of Type 1 and can be compared with the case of Type 1. The HOMO energy level of the hole modulating moiety is higher than that of the host compound.

[0068] The hole regulation portion of the composite light-emitting compound can structurally surround the light-emitting portion when holes are injected into the light-emitting layer and captured by the light-emitting portion, thereby reducing the possibility of chemical reactions with surrounding substances and helping to stabilize the light-emitting portion. In addition, since the HOMO energy level of the hole regulation portion is higher than the HOMO energy level of the host compound, the hole regulation portion can regulate the amount of holes injected into the light-emitting layer by forming an additional path for holes to move. As a result, the hole regulation portion can function inside the light-emitting layer to achieve an optimal balance between holes and electrons. Through this mechanism, the organic light-emitting diode device using the composite light-emitting compound can maintain stable brightness even under long-term driving.

[0069] The composite light-emitting compound may have a structure distinguished by three regions, including a first portion corresponding to a hole regulating moiety, a second portion corresponding to a connecting moiety, and a third portion corresponding to a light-emitting moiety, as shown below.

[0070] Part 1 - Part 2 - Part 3

[0071] The composite luminescent compound can be designed by selecting the hole regulating compound that induces the first part and the luminescent compound that induces the third part so that they can meet certain conditions as described above when chemically combined, and form a connecting part corresponding to the second part to connect them.

[0072] As the first part, the hole regulating part has the first function of maintaining the charge balance inside the light-emitting layer by regulating the movement of holes to the light-emitting layer.

[0073] As the hole regulating part of the first part, its second function is to spatially protect a specific part of the light-emitting part, thereby reducing the probability of the light-emitting part in the excited state interacting with other surrounding molecules.

[0074] The third function of the hole regulating part as the first part is to minimize the concentration quenching phenomenon between adjacent light-emitting parts by reducing the interaction between the light-emitting parts.

[0075] Furthermore, the HOMO-LUMO energy gap of the hole modulating moiety should be greater than the maximum emission wavelength energy of the light-emitting moiety. In this case, the hole modulating moiety can stabilize the light-emitting moiety as described above without receiving energy from the light-emitting moiety. On the other hand, if the HOMO-LUMO energy gap of the hole modulating moiety is less than the maximum emission wavelength energy, energy from the light-emitting moiety may be transferred to the hole modulating moiety, causing the hole modulating moiety to emit light.

[0076] HOMO energy can be measured using methods such as cyclic voltammetry (CV), ultraviolet photoelectron spectroscopy (UPS), and AC2, while LUMO energy can be measured using UV absorption spectroscopy or cyclic voltammetry (CV). The HOMO-LUMO energy gap can be calculated from the difference between the measured HOMO and LUMO energies.

[0077] The maximum emission wavelength energy is the wavelength at which the compound emits the most photons when excited by its maximum absorption wavelength. The maximum emission wavelength energy is measured when the luminescent compound is diluted to a concentration of approximately 2 micromolar in an organic solvent such as toluene, dichloromethane, or THF.

[0078] The hole regulating portion can be designed as a C6-50 aromatic ring or a C5-50 aromatic hetero-condensed ring, or an organic metal compound derived from the ring and a metal, which satisfies the following conditions: the HOMO-LUMO energy gap energy of the hole regulating portion is greater than the maximum emission wavelength energy of the light-emitting portion, and the HOMO energy level of the hole regulating portion is higher than the HOMO energy level of the main compound.

[0079] In the organometallic compound, the metal may be, for example, Cu, Fe, Ni, Co, Ir, Pt, etc., but these are only examples and are not limited thereto.

[0080] In one embodiment, the hole regulating portion comprises:

[0081] (i) at least one atom having an unshared electron pair contained in the HOMO or LUMO wave function of the hole modulating moiety, or

[0082] (ii) The hole regulating moiety may be a C6-50 aromatic ring having at least one substituent represented by the structure of the following Chemical Formula 1; or a C5-50 aromatic hetero-condensed ring having at least one substituent represented by the structure of the following Chemical Formula 1.

[0083] In the above-mentioned (ii), the unshared electron pair N in Chemical Formula 1 is included.

[0084] Chemical formula 1:

[0085]

[0086] In the chemical formula 1,

[0087] L is a single bond, or a divalent group selected from the group consisting of a C1-30 alkylene group, a C3-30 cycloalkylene group, a C2-30 heterocycloalkylene group, a C1-30 alkylsilylene group, a C3-30 cycloalkylsilylene group, a C2-30 heterocycloalkylsilylene group, a C1-30 arylsilylene group, a C7-30 alkylarylsilylene group, a C9-30 cycloalkylarylsilylene group, a C8-30 heterocycloalkylarylsilylene group, oxygen, sulfur, a divalent group of a C6-30 arylphosphine group, a divalent group of a C6-30 arylphosphine oxide group, a C6-30 arylene group, a C2-30 heteroarylene group, and combinations thereof,

[0088] Z' is absent, or represents a single bond, or is an atom selected from the group consisting of elements of Groups IIIA, IVA, VA, and VIA. When Z' is an atom, it may have a substituent selected from hydrogen, a C1-30 alkyl group, a C3-30 cycloalkyl group, a C2-30 heterocycloalkyl group, a C6-30 aryl group substituted or unsubstituted with an additional substituent, a C2-30 heteroaryl group substituted or unsubstituted with an additional substituent, and combinations thereof, in terms of stoichiometric ratio.

[0089] Ar 2 and Ar 3 Each is independently a C1-30 alkyl group, a C3-30 cycloalkyl group, a C2-30 heterocycloalkyl group, a C3-30 allyl group, a C6-30 aryl group which may be substituted or unsubstituted by an additional substituent, or a C2-30 heteroaryl group which may be substituted or unsubstituted by an additional substituent, wherein Ar 2 and Ar 3 Can each independently connect with the L to form a condensed ring,

[0090] The additional substituent is selected from C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 allyl, C6-30 aryl, C2-30 heteroaryl, C1-30 alkylamino, C3-30 cycloalkyleneamino, C2-30 heterocycloalkyleneamino, C7-30 alkylarylamino, C9-30 cycloalkylarylamino, C8-30 heterocycloalkylarylamino, C1- C3-30 alkylsilyl, C3-30 cycloalkylsilyl, C2-30 heterocycloalkylsilyl, C6-30 arylsilyl, C7-30 alkylarylsilyl, C9-30 cycloalkylarylsilyl, C8-30 heterocycloalkylarylsilyl, C1-30 alkylthio, C3-30 cycloalkylthio, C2-30 heterocycloalkylthio, C6-30 arylthio, and combinations thereof,

[0091] Indicates a connection point.

[0092] In one example, the substituent represented by the structure of Chemical Formula 1 may be any one of the structures of the following Chemical Formulas D-1 to D-20. In other words, the hole regulating moiety may include the structures represented by the following Chemical Formulas D-1 to D-20.

[0093]

[0094]

[0095] In the chemical formulas D-1 to D-20,

[0096] Y is each independently carbon or nitrogen,

[0097] X'" are each independently oxygen, nitrogen, sulfur or selenium,

[0098] R'" is each independently selected from hydrogen, deuterium, C1-20 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C3-30 allyl, C6-20 aryl, C2-20 heteroaryl, C1-20 alkylamino, C3-20 cycloalkylamino, C2-20 heterocycloalkylamino, halogen, CN, C1-20 alkylsilyl, C3-20 cycloalkylsilyl, C2-20 heterocycloalkylsilyl, C6-20 arylsilyl, and combinations thereof,

[0099] u are each independently an integer from 0 to 20,

[0100] Dashed lines indicate connection sites.

[0101] The second portion's primary function is to ensure a certain distance and spacing between the hole modulating portion and the light-emitting portion. This allows the hole modulating portion to maintain a spatial position and angle that prevents chemical interaction with the light-emitting portion, thereby protecting a specific portion of the light-emitting portion. This significantly reduces the probability of chemical and Coulombic interactions with surrounding dopants, host materials, and excitons.

[0102] The second function of the second portion is to minimize spatial overlap of the HOMO or LUMO wave functions between the hole-modulating portion and the light-emitting portion. This is because if the wave functions overlap significantly due to the overlapping conjugated structures of the hole-modulating portion and the light-emitting portion, the emission wavelength of the light-emitting portion may shift to a longer wavelength or reduce the luminescence efficiency.

[0103] The second portion may be formed by connecting the hole regulating portion and the light emitting portion by a screw bond.

[0104] In one example, the hole regulating moiety and the light emitting moiety may be connected via a spiro bond using carbon atoms, silicon atoms, Sn atoms, or Ge atoms as spiro atoms.

[0105] The hole regulating part is connected to the light emitting part through a spiro bond, and the second part corresponds to the spiro atom. The difference is that the hole regulating part or the light emitting part does not contain the spiro atom.

[0106] The spiro bond forming the second part should be formed in a manner that does not significantly affect the electronic state of each of the hole adjustment part (first part) and the light-emitting part (third part). Wherein, "no significant effect" means that one of the first part or the third part should not cause the change in the HOMO energy level, LUMO energy level or HOMO-LUMO energy gap energy of the other part to exceed 0.2eV. The definition standard of the electronic state of each part in the composite light-emitting compound can be an independent compound state, that is, the connecting part (second part) in each part (first part or third part) is separated, and the separated part is replaced by hydrogen without containing the connecting part. In other words, it can be compared with the independent compound state in which the various parts connected by the spiro bond are separated and their positions are replaced by two hydrogens. In other words, when the spiro bond is separated, the two bonds connected to the opposite part are removed from the spiro atom and replaced by two hydrogens to obtain the independent compound state. At this time, the change in the degree of conjugation of each compound caused by the second part (connecting part) and the change in the electronic state caused thereby are regarded as the influence of the second part (connecting part), rather than the influence of the opposite part.

[0107] The light-emitting portion as the third portion emits light by receiving energy of excitons formed in the host compound.

[0108] The light-emitting portion may be derived from a light-emitting substance (referred to as a light-emitting compound in this specification) capable of emitting light in an organic light-emitting diode.

[0109] The light-emitting compound (light-emitting substance) may be a compound that can be used as a dopant compound in an organic light-emitting diode. A dopant compound that can achieve a desired color can be selected as the light-emitting compound according to the purpose, thereby inducing a light-emitting portion.

[0110] In one example, the light-emitting portion may have a conjugated structure, and its quantum efficiency in the visible light wavelength range of 400 nm to 700 nm is greater than 20%.

[0111] In one example, the light-emitting portion may have a conjugated structure, and its quantum efficiency in the near-infrared wavelength range of 700 nm to 2500 nm is greater than 0.5%.

[0112] For example, the light-emitting portion is a C6-50 aromatic ring, a C5-50 aromatic hetero-condensed ring, or an organometallic compound derived from the ring and combined with a metal.

[0113] In the organometallic compound, the metal may be, for example, Cu, Fe, Ni, Co, Ir, Pt, etc., but these are merely examples and are not limited thereto. It is a prerequisite that the organometallic compound that induces the luminescent portion is a luminescent substance that can emit light.

[0114] The light-emitting portion may contain carbon and hydrogen (the definition of hydrogen includes hydrogen, deuterium and tritium, that is, the light-emitting portion includes at least one selected from the group consisting of hydrogen, deuterium, tritium and combinations thereof), and as an example, may include pyrene, anthracene, fluorene, benzofluorene or benzanthracene skeletons.

[0115] Specific examples of the luminescent compound (or luminescent substance) may include the following compounds, but are not limited thereto.

[0116]

[0117] In the formula, Ar and R can be substituted or unsubstituted C1-20 alkyl, substituted or unsubstituted C3-20 cycloalkyl, substituted or unsubstituted C2-20 heterocycloalkyl, substituted or unsubstituted C6-30 aryl, substituted or unsubstituted C2-30 heteroaryl, or substituted or unsubstituted C6-30 arylamine, and X is nitrogen, oxygen, sulfur, carbon, silicon, Ge or P element.

[0118] Thus, as for the compound of the aforementioned structural formula, the luminescent compound may be a boron compound substituted by nitrogen, oxygen, sulfur, carbon, silicon, Ge, P, etc., a pyrene compound, a compound having a nitrogen-containing conjugated structure, etc., but is not limited thereto.

[0119] In addition, the luminescent compound can be a known luminescent substance. For example, the luminescent compound can be anthracene, perylene, tetracene, (Chrysene), coumarin (Coumarine), pyrromethene (Pyromethene) and other luminophores with conjugated structures.

[0120] In one example, the luminescent compound and the luminescent moiety may include a conjugated structure forming a HOMO or LUMO wave function, and the conjugated structure may include boron.

[0121] The light emission mechanism of the light emitting portion may include fluorescence emitting light from a singlet state, phosphorescence emitting light from a triplet state, and delayed fluorescence emitting light by energy transfer from a triplet state to a singlet state.

[0122] As described above, the composite light-emitting compound can be designed by connecting the hole regulating moiety to the light-emitting compound via a linking moiety.

[0123] When the hole-modulating compound induced by the hole-modulating portion is connected to the light-emitting compound through a connecting portion to form the composite light-emitting compound, the substituents contained in the light-emitting compound or the hole-modifying compound can be appropriately modified so that these parts form a chemical bond with each other or with the connecting portion, thereby inducing the light-emitting portion and the hole-modifying portion. At this time, the modified portion for chemical bonding will not significantly change the luminescent properties, band gap energy, energy efficiency, etc. unique to each of the hole-modifying compound and the light-emitting compound. For example, when the substituent in the light-emitting compound is replaced by another substituent to form a chemical bond, although the light-emitting portion can be formed, the luminescent properties, band gap energy, energy efficiency, etc. of the light-emitting portion will not be significantly affected by the replaced substituent.

[0124] The phrase "not significantly affected" means that the hole modulating compound and the luminescent compound do not deviate from the detailed descriptions of the hole modulating compound and the luminescent compound described herein. Specifically, "appropriate" modification of the substituents of the hole modulating compound and the luminescent compound during chemical bonding means that the resulting composite luminescent compound conforms to the descriptions of this specification. This means that the substituent modification achieves the general substituent effect of altering the band gap of the luminescent compound or improving the quantum efficiency, meaning that the band gap energy, efficiency, and other parameters do not change dramatically by more than 80%.

[0125] In one example, the band gap energy of the hole regulating portion may be 1 eV to 4.7 eV, and the band gap energy of the light emitting portion may be 0.5 eV to 3.5 eV.

[0126] The hole modulating moiety of the composite luminescent compound does not significantly affect the unique luminescent properties of the luminescent portion, while simultaneously regulating hole mobility in the luminescent layer to achieve charge balance. Furthermore, the hole modulating moiety maintains a spatial position and angle that prevents chemical interaction with the luminescent portion, while protecting specific portions of the luminescent portion, thereby significantly reducing the probability of chemical and Coulombic interactions with other surrounding dopant substances, host substances, and excitons.

[0127] Based on the above reasons, the composite light-emitting compound can improve the light emission stability when driving the organic light-emitting diode device.

[0128] In one example, the composite luminescent compound can be any one of the following compounds.

[0129]

[0130]

[0131]

[0132]

[0133]

[0134] The compound has a structure in which a hole regulating part and a light emitting part are connected by a spiro bond, and the electron regulating part and the light emitting part on both sides are distinguished based on a spiro atom.

[0135] The host compound may generally be a known host substance capable of forming a light-emitting layer.

[0136] For example, the light-emitting layer consists only of the composite light-emitting compound and the host compound.

[0137] In one embodiment, the host compound may include at least one or more. When the light-emitting layer contains two or more host compounds, the HOMO energy level of the hole regulating part is higher than the HOMO energy level of at least one of the two or more host compounds. Therefore, when there are two or more host compounds, the host compound with the lowest HOMO energy level among the two or more host compounds is compared with the HOMO energy level of the hole regulating part. However, when a substance that receives energy from the light-emitting part of the composite light-emitting compound and emits secondary light is included, the secondary light-emitting substance does not belong to the host compound. The secondary light-emitting substance can be an additional dopant compound described below.

[0138] In one example, the light-emitting layer may include at least two composite light-emitting compounds.

[0139] In one example, the composite light-emitting compound may contain at least two or more hole-regulating moieties.

[0140] Specifically, the composite light-emitting compound may include two or more hole regulating moieties connected to one light-emitting moiety. In this case, the composite light-emitting compound also forms two connecting moieties, wherein each hole regulating moiety is connected to a light-emitting moiety.

[0141] In one embodiment, the light-emitting layer may include at least two hole-modulating moieties. For example, when two hole-modulating moieties are present in the light-emitting layer, the two hole-modulating moieties may also be present in a single composite light-emitting compound, and each molecule in multiple identical or different composite light-emitting compounds may include a different hole-modulating moiety. For example, when a composite light-emitting compound includes at least two hole-modulating moieties, each hole-modulating moiety may be the same or different. For example, when the light-emitting layer includes more than one composite light-emitting compound, the hole-modulating moiety included in each molecule in the composite light-emitting compound may be the same or different.

[0142] When two or more hole-modulating moieties are present in the light-emitting layer, the HOMO energy levels of all of the hole-modulating moieties are higher than the HOMO energy level of the host compound. For example, when two or more hole-modulating moieties are present, the HOMO energy levels of all of the two or more hole-modulating moieties are compared with the HOMO energy level of the host compound.

[0143] When two or more hole-modulating moieties are present in the light-emitting layer and two or more host compounds are present, the HOMO energy levels of all hole-modulating moieties present in the light-emitting layer are higher than the HOMO energy level of at least one host compound. In other words, the HOMO energy levels of all types of hole-modulating moieties present in the light-emitting layer are higher than the HOMO energy level of the host compound type with the lowest HOMO energy level among the host compound types.

[0144] The light-emitting layer may further include an additional dopant compound. The additional dopant compound absorbs the luminescent energy of the light-emitting portion and re-emit it. Therefore, the maximum emission wavelength energy of the additional dopant compound is lower than the maximum emission wavelength energy of the light-emitting portion. By using the additional dopant compound, low-energy luminescence can be achieved.

[0145] The maximum emission wavelength energy is the wavelength with the highest photon energy in the emission spectrum. The maximum emission wavelength is calculated from the onset value of the emission start position. The maximum emission wavelength is calculated from the wavelength with the highest emission intensity.

[0146] The detailed description of the additional dopant compound is the same as that of the luminescent compound (or luminescent substance) that induces the luminescent portion. For example, the additional dopant compound can be a known dopant compound or luminescent substance.

[0147] In one example, the light-emitting layer may contain greater than or equal to 0.1 mol % and less than 50 mol %, for example, 0.1 mol % to 30 mol %, of the composite light-emitting compound, but is not limited thereto.

[0148] In one example, the molar ratio of the composite light-emitting compound to the host compound in the light-emitting layer can be 1:1.01 to 1000, specifically, 1:1.01 to 100.

[0149] In one example, the molar ratio of the composite light-emitting compound to the additional dopant compound in the light-emitting layer may be 1:0.01 to 1, specifically, 1:0.01 to 0.1.

[0150] In one embodiment, the complex luminescent compound may include at least one deuterium.

[0151] In the organic light emitting diode, the light emitting layer may further include phosphorescent materials to further improve the light emitting efficiency of the light emitting layer.

[0152] In one example, the light-emitting layer may further include a phosphorescent material containing Pt or Ir.

[0153] The compound represented by the following structural formula is an example of an organometallic compound generally used as a phosphorescent substance.

[0154]

[0155] In the formula, R can be C1-20 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C6-30 aryl, etc.

[0156] In the organic light emitting diode, the light emitting layer may further include a delayed fluorescent substance to further improve the light emitting efficiency of the light emitting layer.

[0157] In one embodiment, the light-emitting layer may further include a delayed fluorescent substance having an energy difference between a singlet state and a triplet state of 0.3 eV or more.

[0158] The compound represented by the following structural formula is an example of a commonly used delayed fluorescent substance.

[0159]

[0160] In the formula, Ar can be C1-20 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C6-30 aryl, etc.

[0161] The organic light emitting diode may include one selected from the group consisting of a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a combination thereof as an organic layer.

[0162] In one example, the organic light emitting diode may include an anode, a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (EML), an electron transport layer (ETL), and a cathode in sequence.

[0163] The organic light emitting diode may be a tandem organic light emitting diode including a plurality of organic light emitting units.

[0164] A plurality of organic light-emitting units may be stacked in sequence, and a charge generation layer (CGL) may be included between each organic light-emitting unit to distribute charges smoothly to the light-emitting layer of each organic light-emitting unit.

[0165] The tandem organic light-emitting diode comprises a light-emitting layer, wherein at least one organic light-emitting unit comprises the composite functional compound.

[0166] In the series-connected organic light-emitting diode, the detailed description of the composite functional compound is as described above.

[0167] The following examples and comparative examples of the present invention are described. The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0168] (Example)

[0169] Synthesis example

[0170] Synthesis of comparative compound 1

[0171]

[0172] 8.48 g of comparative compound 1-1 (10.0 mmol) was dissolved in tert-butylbenzene (32 ml) and cooled to 0° C. Under a nitrogen atmosphere, 8.0 mL (20.0 mmol) of 2.5 M n-butyllithium solution (in hexane) was added, and the mixture was stirred at room temperature for 3 hours.

[0173] The reaction mixture was then cooled to 0°C again, 1.90 mL of boron tribromide (20.0 mmol) was added, and the mixture was stirred at room temperature for 0.5 hours. The reaction mixture was then cooled to 0°C again, 3.51 mL of N,N-diisopropylethylamine (20.0 mmol) was added, and the mixture was stirred at 60-70°C for 2 hours.

[0174] The reaction mixture was cooled to room temperature, and the organic layer was extracted with ethyl acetate. The solvent of the extracted organic layer was dried over MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography (DCM / hexane).

[0175] Then, the product was recrystallized using a DCM / acetone mixed solvent to obtain 1.05 g of the comparative compound 1 with a yield of 12%.

[0176] MS (ACPI) m / z: 779 [M+H]

[0177] NMR: δH (500MHz; CDCl3; Me4Si) 8.94 (s, 1H), 8.84 (d, J=10Hz, 1H), 7.69 (d, 2H), 7.66-7.56 (m, 2H), 7.51-7.45 (d, 1H), 7.42 (s, 1H), 7.34-7.28 (m, 3 H), 7.19 (d, 1H), 6.67 (s, J=8Hz, 2H), 6.15 (d, 1H), 6.06 (s, 1H), 1.89 (s, 3 H), 1.64(d, 4H), 1.46(s, 20H), 1.37(s, 11H), 1.25(s, 3H), 1.22(s, 10H).

[0178] Synthesis of compound 2

[0179]

[0180] The synthesis was performed in the same manner as the above comparative compound 1, except that compound 2-1 was used instead of comparative compound 1-1 at the same molar ratio.

[0181] Thereafter, 1.0 g of compound 2 was obtained with a yield of 10%.

[0182] MS (ACPI) m / z: 1004 [M+H]

[0183] NMR: δH (500MHz; CDCl3; Me4Si) 9.19 (d, 1H), 8.90 (dd, 2H), 8.43-8.32 (m, 1H), 8.25 -8.16(m, 1H), 8.11-7.99(m, 2H), 7.93(dd, 1H), 7.70-7.60(m, 2H), 7.54-7.38(m, 6 H), 7.37-7.26(m, 4H), 7.25-7.14(m, 1H), 7.13-7.04(m, 4H), 7.04-6.90(m, 3H), 6. 89-6.60 (m, 12H), 6.58-6.45 (m, 2H), 5.93-5.80 (m, 2H), 2.24 (dd, 3H), 2.03 (d, 3H).

[0184] Synthesis of compound 3

[0185]

[0186] The synthesis was carried out in the same manner as the above compound 2, except that compound 3-1 was used instead of comparative example compound 2-1 at the same molar ratio.

[0187] Thereafter, 0.9 g of compound 3 was obtained with a yield of 9%.

[0188] MS (ACPI) m / z: 1004 [M+H]

[0189] NMR: δH (400MHz; CDCl3; Me4Si) δ9.15-9.12 (m, 1H), 8.81 (dd, J=7.9, 3.5Hz, 1H), 8.22-8.18 (m, 2H), 7.99-7.89 (m, 2H), 7.81-7.68 (m, 4H), 7.56- 7.38(m, 11H), 7.18-6.74(m, 16H), 6.68-6.57(m, 2H), 6.55-6.40(m, 1H) , 6.09-5.81 (m, 2H), 2.35 (d, J=2.2Hz, 3H), 2.17 (dd, J=9.3, 7.2Hz, 3H).

[0190] Synthesis of compound 4

[0191]

[0192] The synthesis was carried out in the same manner as the above compound 2, except that compound 4-1 was used instead of comparative example compound 2-1 at the same molar ratio.

[0193] Thereafter, 1.0 g of the present compound 4 was obtained with a yield of 9%.

[0194] MS (ACPI) m / z: 1046 [M+H]

[0195] NMR: δH (400MHz; CDCl3; Me4Si) 9.13 (s, 1H), 8.86-8.83 (m, 1H), 7.92-7.90 (m, 1H), 7.78 (d, J=8.0Hz, 1H), 7.73-7.64 (m, 6H), 7.44-7.27 (m, 11H), 7.17-6.86(m, 13H), 6.80-6.57(m, 5H), 6.49(d, J=4.0Hz, 1H), 6.37(d, J= 8.0Hz, 1H), 6.12 (t, 2H), 5.89 (d, J=8.0Hz, 1H), 2.36 (s, 3H), 0.96 (s, 9H)

[0196] Experimental Example 1. Measurement of HOMO-LUMO Energy Levels

[0197] Differential pulse voltammetry (DPV) analysis was performed on HOST-1, 2, and 3, as well as compounds 2, 3, and 4, in DMF. The results are shown in Tables 1 and 2. Referring to the figures above, it can be seen that the HOMO energy level of the hole-modulating moiety is higher than that of HOST. The instrument used was an Autolab Electrochemical Workstations PGSTAT101 potentiostat / galvanostat.

[0198]

Table 1

[0199]

[0200]

Table 2

[0201]

[0202] Fabrication of organic light-emitting diodes

[0203] The ITO surface was treated with UV ozone at normal pressure for 3 minutes.

[0204] Device in 10 -7 The treatment was carried out in the following order in a torr vacuum chamber.

[0205]

[0206] Comparative Example 1 (Device 1)

[0207] Deposit HATCN as hole injection material to a thickness of Deposit compound A as a hole transporter to a thickness of Deposit compound B as an electron blocking layer to a thickness of

[0208] HOST-1 was used as the light-emitting layer, doped with comparative compound 1 (5 mol%), and deposited to a thickness of

[0209] Deposit compound C as a hole blocking layer to a thickness of

[0210] Deposit a 1:1 ratio of compound D and LiQ as an electron transport layer to a thickness of

[0211] LiQ was deposited as an electron injection layer to a thickness of

[0212] Deposit Al as electrode to a thickness of

[0213] Comparative Example 2 (Device 2)

[0214] The device was prepared in the same manner as Comparative Example 1, except that the light-emitting layer of the device 1 was doped with the comparative compound 1 (10 mol %).

[0215] Comparative Example 3 (Device 3)

[0216] The device was prepared in the same manner as Comparative Example 1, except that HOST-2 was used instead of HOST-1 in the light-emitting layer of device 1.

[0217] Comparative Example 4 (Device 4)

[0218] The device was prepared in the same manner as in Comparative Example 2, except that HOST-2 was used instead of HOST-1 in the light-emitting layer of device 2.

[0219] Comparative Example 5 (Device 7)

[0220] The device was prepared in the same manner as device 1, except that HOST-3 was used instead of HOST-1 in the light-emitting layer of device 1 and 2 mol % of comparative compound 1 was doped.

[0221] Example 1 (Device 5)

[0222] The same method as Comparative Example 2 was used except that Compound 2 was used instead of Comparative Compound 1 in the light-emitting layer of Device 2.

[0223] Example 2 (Device 6)

[0224] The same method as Comparative Example 2 was used to prepare the device, except that the compound 3 of the present invention was used instead of the comparative compound 1 in the light-emitting layer of the device 2.

[0225] Example 3 (Device 8)

[0226] The device 5 was prepared in the same manner as Comparative Example 1, except that the light-emitting layer of the device 5 was doped with 3 mol % of Compound 4.

[0227] The doping percentages that exhibited the maximum luminous efficiency in the following devices were measured, as well as the maximum luminous efficiency when 10 mA / cm was applied to the device. 2 The time required for the brightness to drop by 5% at the current.

[0228]

Table 3

[0229]

[0230] For devices that transfer energy from the host to the dopant to induce dopant luminescence, in Comparative Examples 1 to 4, luminescence occurs at the interface between the electron blocking layer and the host, as well as luminescence from the dopant. This is due to the accumulation of holes and electrons at the interface between the electron blocking layer and the host. 2 The ratio of dopant luminescence and interface luminescence is calculated from the EL luminescence spectrum under 0.1 % and 0.2 % respectively. It can be observed that the dopant luminescence rate is very low, namely 16%, 9%, 23% and 17% respectively. In particular, when the dopant content is as high as 10%, the luminescence rate of the dopant is even lower. This is believed to be because the high doping concentration captures holes and hinders their migration into the interior of the main body, resulting in greater interface luminescence. Compounds 2 and 3 of the present invention connect the hole regulating part to the luminescent dopant through a spiro bond. In this way, the holes are injected deep into the main body, thereby reducing the interface luminescence and increasing the dopant luminescence rate.

[0231] According to these characteristics, compounds 2 and 3 of the present invention exhibit relatively high dopant luminescence efficiency in devices 5 and 6, which are 48% and 39%, respectively, thereby adjusting the y value of the CIE color coordinate from the 0.5 range to the 0.2 range.

[0232] This proves that the amount of holes injected into the host EML layer increases due to the influence of the hole regulation part, thereby affecting the charge balance of holes and electrons in the EML layer, enabling the dopant to emit light efficiently.

[0233]

Table 4

[0234]

[0235] In device 7 of the comparative example in the above table, the exciton density is high because holes and electrons combine at the interface. The anthracene host used here is a well-known substance that can improve the luminous efficiency by forming a singlet state through triplet-triplet collisions. This is more likely to happen when the interface exciton density is high. Therefore, the quantum efficiency of device 7 is as high as 7.44. However, when the exciton density is high, the stability of the organic matter is reduced and the brightness of the device decreases rapidly. Compound 4 developed by the present invention contains a hole regulating part, whose function is to allow holes to enter the interior of the light-emitting layer. As the exciton formation area inside the light-emitting layer expands, the efficiency decreases due to the reduction of singlet formation caused by triplet-triplet collisions, but it can be confirmed that the device life is significantly improved, Figure 4 This is also confirmed. Although the present invention has been described with reference to the exemplary drawings above, the present invention is not limited to the embodiments and drawings disclosed in this specification. Obviously, those skilled in the art can make various modifications within the scope of the technical concept of the present invention. At the same time, although the effects based on the configuration of the present invention are not explicitly described when describing the embodiments of the present invention, the effects that can be foreseen by the configuration should be recognized.

Claims

1. An organic light emitting diode, comprising a first electrode, a second electrode, and a light emitting layer located between the first electrode and the second electrode, characterized in that: The light-emitting layer comprises a composite light-emitting compound and a host compound, The composite light-emitting compound comprises a hole regulating part, a connecting part and a light-emitting part, The composite light-emitting compound comprises a connecting portion connecting the hole regulating portion and the light-emitting portion via a spiro bond, The hole regulating part is a substituted or unsubstituted C6-50 aromatic ring or C5-50 aromatic hetero-condensed ring, or an organometallic compound derived from the ring and metal. the hole modulating moiety comprises at least one atom having an unshared electron pair contained in the HOMO or LUMO wave function of the hole modulating moiety, The HOMO-LUMO energy gap of the hole adjustment part is greater than the maximum emission wavelength energy of the light emitting part, The HOMO energy level of the hole modulating moiety is higher than the HOMO energy level of the host compound.

2. The organic light emitting diode according to claim 1, wherein: The light-emitting portion is derived from a light-emitting substance.

3. The organic light emitting diode according to claim 1, wherein The light emitting portion has a conjugated structure and has a quantum efficiency of 20% or more in a visible light wavelength range of 400 nm to 700 nm.

4. The organic light emitting diode according to claim 1, wherein The light-emitting portion has a conjugated structure and has a quantum efficiency of 0.5% or more in a near-infrared wavelength range of 700 nm to 2500 nm.

5. The organic light emitting diode according to claim 1, wherein The light emission mechanism of the light emitting portion includes fluorescence emitting from a singlet state, phosphorescence emitting from a triplet state, and delayed fluorescence emitting light by transferring energy from a triplet state to a singlet state.

6. The organic light emitting diode according to claim 1, wherein: The complex luminescent compound comprises at least one deuterium.

7. The organic light emitting diode according to claim 1, wherein: The spiro atom is a carbon atom, a silicon atom, a Sn atom or a Ge atom.

8. The organic light emitting diode according to claim 1, wherein: The hole regulating portion and the light emitting portion form the connecting portion through a spiro bond, and the change in HOMO energy level, LUMO energy level or HOMO-LUMO band gap energy between them does not exceed 0.2 eV.

9. The organic light emitting diode according to claim 1, wherein: The luminescent portion is a C6-50 aromatic ring, a C5-50 aromatic hetero-condensed ring, or an organic metal compound derived from the aromatic ring and combined with a metal.

10. The organic light emitting diode according to claim 1, wherein The light emitting portion includes a conjugated structure forming a HOMO or LUMO wave function, and the conjugated structure includes boron.

11. The organic light emitting diode according to claim 1, wherein: The hole modulating moiety comprises (i) at least one atom having an unshared electron pair contained in the HOMO or LUMO wave function of the hole modulating moiety, or (ii) the hole regulating moiety is a C6-50 aromatic ring having at least one substituent represented by the structure of the following chemical formula 1; or a C5-50 aromatic hetero-condensed ring having at least one substituent represented by the structure of the following chemical formula 1: Chemical formula 1: In the chemical formula 1, L is a single bond, or a divalent group selected from the group consisting of a C1-30 alkylene group, a C3-30 cycloalkylene group, a C2-30 heterocycloalkylene group, a C1-30 alkylsilylene group, a C3-30 cycloalkylsilylene group, a C2-30 heterocycloalkylsilylene group, a C1-30 arylsilylene group, a C7-30 alkylarylsilylene group, a C9-30 cycloalkylarylsilylene group, a C8-30 heterocycloalkylarylsilylene group, oxygen, sulfur, a divalent group of a C6-30 arylphosphine group, a divalent group of a C6-30 arylphosphine oxide group, a C6-30 arylene group, a C2-30 heteroarylene group, and combinations thereof, Z' is absent, or represents a single bond, or is an atom selected from the group consisting of elements of Groups IIIA, IVA, VA, and VIA. When Z' is an atom, it can have a substituent selected from hydrogen, C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C6-30 aryl substituted or unsubstituted with additional substituents, C2-30 heteroaryl substituted or unsubstituted with additional substituents, and combinations thereof, in stoichiometric ratios. Ar 2 and Ar 3 Each is independently a C1-30 alkyl group, a C3-30 cycloalkyl group, a C2-30 heterocycloalkyl group, a C3-30 allyl group, a C6-30 aryl group substituted or unsubstituted by an additional substituent, or a C2-30 heteroaryl group substituted or unsubstituted by an additional substituent, wherein Ar 2 and Ar 3 can each independently connect with the L to form a condensed ring, The additional substituent is selected from C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 allyl, C6-30 aryl, C2-30 heteroaryl, C1-30 alkylamino, C3-30 cycloalkyleneamino, C2-30 heterocycloalkyleneamino, C7-30 alkylarylamino, C9-30 cycloalkylarylamino, C8-30 heterocycloalkylarylamino, C1- C3-30 alkylsilyl, C3-30 cycloalkylsilyl, C2-30 heterocycloalkylsilyl, C6-30 arylsilyl, C7-30 alkylarylsilyl, C9-30 cycloalkylarylsilyl, C8-30 heterocycloalkylarylsilyl, C1-30 alkylthio, C3-30 cycloalkylthio, C2-30 heterocycloalkylthio, C6-30 arylthio, and combinations thereof, Indicates a connection point.

12. The organic light emitting diode according to claim 11, wherein: The substituent represented by the structure of Chemical Formula 1 is represented by any one of the structures of the following Chemical Formulas D-1 to D-20, In the chemical formulas D-1 to D-20, Y is each independently carbon or nitrogen, X'" are each independently oxygen, nitrogen, sulfur or selenium, R'" is each independently selected from hydrogen, deuterium, C1-20 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C3-30 allyl, C6-20 aryl, C2-20 heteroaryl, C1-20 alkylamino, C3-20 cycloalkylamino, C2-20 heterocycloalkylamino, halogen, CN group, C1-20 alkylsilyl, C3-20 cycloalkylsilyl, C2-20 heterocycloalkylsilyl, C6-20 arylsilyl, and combinations thereof, u are each independently an integer from 0 to 20, Dashed lines indicate connection sites.

13. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The light-emitting layer comprises at least two of the composite light-emitting compounds.

14. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The composite light-emitting compound comprises at least two of the hole-modulating moieties.

15. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The light-emitting layer also includes an additional dopant compound.

16. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The light-emitting layer further includes a phosphorescent material containing Ir or Pt.

17. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The light-emitting layer further includes a delayed fluorescent substance having an energy difference between a singlet state and a triplet state of 0.3 eV or more.

18. The organic light emitting diode according to any one of claims 1 to 12, characterized in that The organic light emitting diode is an organic light emitting diode comprising a plurality of organic light emitting units connected in series. At least one of the plurality of organic light emitting units includes the light emitting layer.

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