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 a long - life organic light emitting substance. Background Art

[0002] An organic light emitting diode (OLED) is a device in which holes injected from an anode and electrons injected from a cathode combine in a light emitting layer through a charge transport layer to form excitons and emit light. It was first reported by C.W.Tang in Appl.Phys.Lett 51, 913 in 1987. At that time, the light emitting layer was composed of a single substance, Alq3. However, in J.Appl.Phys., Vol.65, 3610 in 1989, the emission wavelength was adjusted and the efficiency was improved by doping a small amount of a red light emitting compound, DCM, and a green light emitting compound, Coumarine 540, into Alq3. Summary of the Invention

[0003] Technical Problem

[0004] An object of the present invention is to provide an organic light emitting diode that can minimize the light brightness even under long - term driving by improving the emission stability of the light emitter.

[0005] The object of the present invention is not limited to the above - mentioned object. Other objects and advantages not mentioned in the present invention can be understood from the following description and can be more clearly understood through the embodiments of the present invention. In addition, it is easily understood that the objects and advantages of the present invention can be achieved by the means and combinations described in the claims.

[0006] Technical Solution

[0007] In one example of the present invention, there is provided an organic light emitting diode,

[0008] comprising a first electrode, a second electrode, and a light emitting layer located between the first electrode and the second electrode,

[0009] wherein the light emitting layer contains a composite light emitting compound,

[0010] the composite light emitting compound contains an electron - regulating part and a light - emitting part,

[0011] the composite light emitting compound contains a connecting part that connects the electron - regulating part and the light - emitting part through a spiro bond,

[0012] the electron - regulating part is a substituted or unsubstituted C6 - 50 aromatic ring or C5 - 50 aromatic hetero - condensed ring, or an organometallic compound derived from its combination with a metal,

[0013] The HOMO-LUMO energy gap of the electronic adjustment part is greater than the maximum emission wavelength energy of the light-emitting part,

[0014] The LUMO energy level of the electronic adjustment part is equal to or lower than the LUMO energy level of the light-emitting part.

[0015] Effects of the Invention

[0016] The organic light-emitting diode containing the composite light-emitting compound of the present invention maximizes the reduction of brightness under long-term driving by improving the light-emitting stability of the device.

[0017] In addition to the above effects, the specific embodiments will be described below in combination with the specific effects of the present invention. Brief Description of the Drawings

[0018] Figure 1 Shows the HOMO-LUMO energy levels of typical hosts and dopants and the HOMO-LUMO energy levels of the host and the composite light-emitting compound to be achieved by the present invention. Detailed Description of the Embodiments

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily implement them. The present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0020] In this specification, the term "substituted" means that a hydrogen atom bonded to a carbon atom in a compound is replaced by another substituent. The position where 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.

[0021] In this specification, unless otherwise mentioned, the substituents in the case of "substituted" can be selected from the group consisting of, for example, deuterium, C1-20 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 alkenyl, 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, C1-30 alkoxysilyl, C6-30 arylsilyl, C6-30 aryl, C6-30 arylamino, C2-30 heteroaryl, C6-30 arylphosphinyl, C6-30 arylphosphonyl, C1-30 alkylphosphinyl, C3-30 cycloalkylphosphinyl, C2-30 heterocycloalkylphosphinyl, C1-30 alkylsulfonyl, C3-30 cycloalkylsulfonyl, C2-30 heterocycloalkylsulfonyl and combinations thereof, but are not limited thereto.

[0022] In this specification, unless otherwise defined, "the combination thereof" in the definition of substituents means that there are two or more substituents, or two or more divalent substituents are connected or fused.

[0023] In this specification, the case where two substituents are connected to form a ring includes the case where one of the two substituents is hydrogen and connection occurs when the hydrogen is removed.

[0024] In this specification, unless otherwise mentioned, alkyl includes cycloalkyl and heterocycloalkyl. Additionally, for example, unless otherwise mentioned, alkylamino includes cycloalkylamino and heterocycloalkylamino.

[0025] In this specification, unless otherwise defined, "hetero" means that a compound or a substituent contains a heteroatom, and the heteroatom refers to an atom other than carbon and hydrogen among the atoms forming a heterocyclic compound. For example, it can be N, O, Si, Ge, S, P, B, Se, Te, etc., but is not limited thereto. When a compound or a substituent contains two or more heteroatoms, the same or different heteroatoms can be included. For example, one or two or more heteroatoms can be included. For example, heteroaryl or heterocycloalkyl contains at least one heteroatom as a ring-forming atom.

[0026] In this specification, unless otherwise mentioned, a ring includes a fused ring.

[0027] In one example of the present invention, there is provided an organic light emitting diode

[0028] including a first electrode, a second electrode, and a light emitting layer located between the first electrode and the second electrode.

[0029] The light-emitting layer contains a composite light-emitting compound.

[0030] The composite light-emitting compound contains an electron-regulating part, a linking part, and a light-emitting part.

[0031] The light-emitting layer contains a composite light-emitting compound.

[0032] The composite light-emitting compound contains an electron-regulating part and a light-emitting part.

[0033] The composite light-emitting compound contains a linking part that connects the electron-regulating part and the light-emitting part through a spiro bond.

[0034] The electron-regulating part is a substituted or unsubstituted C6-50 aromatic ring or C5-50 aromatic hetero-fused ring, or an organometallic compound derived from its combination with a metal.

[0035] The HOMO-LUMO energy gap energy of the electron-regulating part is greater than the maximum emission wavelength energy of the light-emitting part.

[0036] The LUMO energy level of the electron-regulating part is equal to or lower than the LUMO energy level of the light-emitting part.

[0037] The organic light-emitting diode uses the composite light-emitting compound designed according to the foregoing conditions to improve the light-emitting stability of the device, thereby realizing an organic light-emitting diode that can also minimize the brightness under long-term driving.

[0038] Generally, in addition to the emission wavelength and efficiency of the organic light-emitting diode, the dopant plays a crucial role in the characteristic of the device's brightness decay with driving time. The composite light-emitting compound is designed and developed by improving the degradation mechanism and energy transfer process of the dopant, so that the device can also exhibit stable brightness under long-term driving.

[0039] The process in which electrons and holes injected into the light-emitting layer combine in the host of the light-emitting layer to form excitons and their energy is transferred to the dopant can be explained by the light-based method (FRET, Resonance Energytransfer) of the following mathematical formula 1 and the electron-based method (Dexter Electron Transfer) of the following mathematical formula 2.

[0040] FRET( Resonance Energy transfer)

[0041] Mathematical formula 1

[0042]

[0043] Dexter Electron Transfer

[0044] Mathematical formula 2

[0045]

[0046] k ET : Rate constant

[0047] r: Distance between the energy donor and the energy acceptor

[0048] τ D : PL decay time of the energy donor

[0049] κ: Orientation factor

[0050] Q D : PL quantum efficiency of the energy donor

[0051] N A : Avogadro's constant

[0052] n: Refractive index

[0053] J: Defined by the following Mathematical formula 3

[0054] Mathematical formula 3

[0055] J = ∫f D (λ)ε A (λ)λ 4 dλ

[0056] f D : Emission spectrum of the energy donor

[0057] ε A : Absorption coefficient of the energy acceptor as a function of wavelength

[0058] L: The sum of Van der Waals radii

[0059] λ: Wavelength

[0060] Once the dopant obtains energy from the host, it enters the excited state. That is, it is in the same state as one of the two electrons in the highest occupied molecular orbital (HOMO) energy level of the dopant moving to the lowest unoccupied molecular orbital (LUMO) energy level. The time required for an electron to jump from the LUMO energy level to the HOMO energy level and re-stabilize ranges from a few nanoseconds to several milliseconds depending on the spin state of the electron. Considering that the vibration motion time of molecules is on the picosecond scale, the excited-state dopant will continuously interact with surrounding molecules before being photo-relaxed. It will form new energy levels, trigger chemical reactions, or decompose, and this series of processes will accelerate the reduction of the luminescence intensity with the driving time of the organic light-emitting diode.

[0061] The HOMO-LUMO energy gap of the dopant is always smaller than that of the host material, but the energy level positions between the two materials are not always constant. Figure 1 In, E HOMO represents the HOMO energy level of each material, and E LUMO represents the LUMO energy level of each material.

[0062] As an example, Type 1 is characterized by comparing the energy levels of the dopant and the host. Type 1 is that the HOMO energy level of the dopant is higher than that of the host, and its type is the same as that of a general host and dopant. 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 from both sides of the light-emitting layer with a thickness of Therefore, the holes are captured by the dopant before the two charges meet to form excitons.

[0063] The LUMO energy level of the dopant is usually higher than that of the host. Thus, it can be considered that electrons move along the LUMO energy level of the host, regardless of the LUMO energy level of the dopant. That is to say, the movement of holes in the light-emitting layer can be controlled by the doping amount of the dopant, but the movement of electrons cannot be controlled.

[0064] Type 2 is characterized by comparing the energy levels of each part in the composite light-emitting compound including the light-emitting part and the electron-regulating part with the energy level of the host. By comparing Type 1 and Type 2, it can be seen that the composite light-emitting compound is formed by connecting the electron-regulating part to the dopant (i.e., the light-emitting material in Type 1), thus including a light-emitting part and an electron-regulating part. The LUMO energy level of the electron-regulating part is lower than that of the light-emitting part.

[0065] The electron-regulating part of the composite light-emitting compound can affect the movement of electrons injected into the light-emitting layer. Thus, the composite light-emitting compound can improve the light-emitting efficiency or device stability by achieving a balance between holes and electrons inside the light-emitting layer. For example, according to the materials of the light-emitting layer and each organic layer forming the organic light-emitting diode, the doping concentration of the composite light-emitting compound can be appropriately adjusted to control the movement of electrons to the light-emitting layer, thereby maximizing the charge balance between holes and electrons inside the light-emitting layer.

[0066] The composite light-emitting compound may have a structure differentiated into three regions, including a first part corresponding to the electron-regulating part, a second part corresponding to the connecting part, and a third part corresponding to the light-emitting part, as follows.

[0067] First part - Second part - Third part

[0068] The composite light-emitting compound can be designed by selecting an electron-regulating compound that induces the first part and a light-emitting compound that induces the third part such that when they are chemically combined, they can meet the certain conditions described above, and forming a connecting part corresponding to the second part to connect them.

[0069] As the electron-regulating part of the first part, its first function is to maintain charge balance by regulating the electron movement inside the light-emitting layer.

[0070] As the electron-regulating part of the first part, its second function is to spatially protect specific parts of the light-emitting part, thereby reducing the probability of interaction between the excited light-emitting part and other surrounding molecules.

[0071] As the electron-regulating part of the first part, its third function is to minimize the concentration quenching phenomenon between dopants by reducing the interaction between the light-emitting parts.

[0072] In addition, the HOMO-LUMO energy gap energy of the electron-regulating part should be greater than the maximum emission wavelength energy of the light-emitting part. In this case, the electron-regulating part can stabilize the light-emitting part as described above without receiving energy from the light-emitting part. Additionally, if the maximum emission wavelength energy of the electron-regulating part is less than the maximum emission wavelength energy of the light-emitting part, there may be a problem where the energy of the light-emitting part is transferred to the electron-regulating part, resulting in the electron-regulating part emitting light.

[0073] The HOMO energy can be measured by methods such as cyclic voltammetry (CV), ultraviolet photoelectron spectroscopy (UPS), and AC2. The LUMO energy can be measured by ultraviolet absorption spectroscopy or cyclic voltammetry (CV). The HOMO-LUMO energy gap can be calculated from the difference between the measured HOMO energy and LUMO energy.

[0074] The maximum emission wavelength energy refers to the wavelength at which the number of photons in the emitted light energy is the largest when the compound is excited by its maximum absorption wavelength. The maximum emission wavelength energy is measured after preparing the luminescent compound in an organic solvent such as toluene, dichloromethane, or THF at a concentration of about 2 micromoles.

[0075] The electron-regulating part can be designed as a C6-50 aromatic ring or a C5-50 aromatic hetero-fused ring that satisfies the following conditions, or an organometallic compound derived from its combination with a metal. The conditions are that the HOMO-LUMO energy gap of the electron-regulating part is greater than the maximum emission wavelength energy of the luminescent part, and the LUMO energy level is equal to or lower than the LUMO energy level of the luminescent part.

[0076] In the organometallic compound, the metal can be, for example, Cu, Fe, Ni, Co, Ir, Pt, etc., but these are only examples and are not limited thereto.

[0077] In one example, the electron-regulating part can be a C6-50 aromatic ring having at least one substituent represented by the following Chemical Formula 1; or a C5-50 aromatic hetero-fused ring having at least one substituent represented by the following Chemical Formula 1.

[0078] Chemical Formula 1:

[0079]

[0080] In the Chemical Formula 1,

[0081] L is a single bond or a divalent group selected from the following group: C1-30 alkylene, C3-30 cycloalkylene, C2-30 heteroalkylene, C1-30 alkylmethylsilylene, C3-30 cycloalkylmethylsilylene, C2-30 heteroalkylmethylsilylene, C1-30 arylmethylsilylene, C7-30 alkylarylmethylsilylene, C9-30 cycloalkylarylmethylsilylene, C8-30 heteroalkylarylmethylsilylene, oxygen, sulfur, a divalent group of C6-30 arylphosphine, a divalent group of C6-30 arylphosphine oxide, C6-30 arylene, C2-30 heteroarylene, and combinations thereof.

[0082] t is an integer from 0 to 5,

[0083] v is 0 or 1,

[0084] Each R" is independently selected from hydrogen, deuterium, C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl optionally substituted with a third additional substituent, C2-30 heteroaryl optionally substituted with a third additional substituent, C1-30 alkylamino, C3-30 cycloalkylamino, C2-30 heterocycloalkylamino, C6-30 arylamino optionally substituted with a third additional substituent, C7-30 alkylarylamino optionally substituted with a third additional substituent, C9-30 cycloalkylarylamino optionally substituted with a third additional substituent, C8-30 heterocycloalkylarylamino optionally substituted with a third additional substituent, halogen, CN, C1-30 alkoxy, C6-30 aryloxy optionally substituted with a third additional substituent, C1-30 alkylsilyl optionally substituted with a third additional substituent, C3-30 cycloalkylsilyl optionally substituted with a third additional substituent, C2-30 heterocycloalkylsilyl optionally substituted with a third additional substituent, C6-30 arylsilyl optionally substituted with a third additional substituent, C7-30 alkylarylsilyl optionally substituted with a third additional substituent, C9-30 cycloalkylarylsilyl optionally substituted with a third additional substituent, C8-30 heterocycloalkylarylsilyl optionally substituted with a third additional substituent, C1-30 alkylthio, C3-30 cycloalkylthio, C2-30 heterocycloalkylthio, C6-30 arylthio, C1-30 arylphosphine, C1-30 arylphosphine oxide, and combinations thereof, provided that at least two of said R" can be connected to each other to form a ring,

[0085] The third additional substituent is selected from C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl, C2-30 heteroaryl, C2-30 alkylamino, C3-30 cycloalkylamino, C2-30 heterocycloalkylamino, C7-30 alkylarylamino, C9-30 cycloalkylarylamino, C8-30 heterocycloalkylarylamino, C1-30 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,

[0086] Each Y is independently nitrogen, oxygen, sulfur, or carbon,

[0087] Indicates the connection part.

[0088] In the Chemical Formula 1, when at least two R" are connected to form a ring, such a ring includes a fused ring. Also, the case where two R" are connected includes: when any one of the two connected R" is hydrogen and this hydrogen (i.e., R") detaches, the Y to which this hydrogen (i.e., R") is connected directly connects to the other of the two connected R".

[0089] In one example, the substituent represented by the structure of Chemical Formula 1 can be any one of the structures of the following Chemical Formulas D-1 to D-13. That is, the electron regulating part may include the structures shown in the following Chemical Formulas D-1 to D-13.

[0090]

[0091] In the Chemical Formulas D-1 to D-13,

[0092] X'" are each independently oxygen, nitrogen, sulfur or selenium,

[0093] R'" are each independently selected from hydrogen, deuterium, C1-30 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl, C2-30 heteroaryl, C2-30 alkylamino, C3-20 cycloalkylamino, C2-20 heterocycloalkylamino, halogen, CN, C1-30 alkylsilyl, C3-20 cycloalkylsilyl, C2-20 heterocycloalkylsilyl, C6-30 arylsilyl and combinations thereof,

[0094] u are each independently an integer from 0 to 20,

[0095] The dashed line indicates the connection part.

[0096] The first function of the second part is to ensure a certain distance and space between the electron regulating part and the light emitting part. In this way, if the electron regulating part maintains a spatial position and angle that does not chemically interact with the light emitting part, specific parts of the light emitting part can be protected, thus facilitating a significant reduction in the probability of chemical interaction and Coulomb interaction with other surrounding dopant substances, host substances and excitons.

[0097] The second function of the second part is to minimize the spatial overlap of the HOMO or LUMO wave functions between the electron regulating part and the light emitting part. This is because if the wave functions overlap due to the overlap of the conjugated structures of the electron regulating part and the light emitting part, it may lead to problems such as the emission wavelength of the light emitting part shifting to a longer wavelength or a decrease in the emission efficiency.

[0098] The second part can be formed by connecting the electronic adjustment part and the light-emitting part through a spiro bond.

[0099] In one example, the electronic adjustment part and the light-emitting part can be connected through a spiro bond using a carbon atom, a silicon atom, a Sn atom, or a Ge atom as the spiro atom.

[0100] The electronic adjustment part and the light-emitting part are connected through a spiro bond. At this time, the second part corresponds to the spiro atom, except that the electronic adjustment part or the light-emitting part does not contain the spiro atom.

[0101] The spiro bond forming the second part should be formed in a manner that does not significantly affect the respective electronic states of the electronic adjustment part (the first part) and the light-emitting part (the third part). Here, "not significantly affect" means that the change in the HOMO energy level, LUMO energy level, or HOMO-LUMO energy gap energy of one part of the first part or the third part should not exceed 0.2 eV for the other part. The definition standard of the electronic state of each part in the composite light-emitting compound can be the independent compound state, that is, the connecting part (the second part) in each part (the first part or the third part) is separated, and the separated part is replaced by hydrogen to form a compound without the connecting part. That is to say, it can be compared with the independent compound state in which each part connected by a spiro bond can be separated, and at the same time, its position is replaced by two hydrogens. That is to say, when the spiro bond is separated, the two bonds connected to the opposite part are removed from the spiro atom, and at the same time, the independent compound state obtained by replacing them with two hydrogens is compared. At this time, the change in the conjugation degree of each compound caused by the second part (the connecting part) and the resulting change in the electronic state are regarded as the influence of the second part (the connecting part), rather than the influence of the opposite part.

[0102] The light-emitting part as the third part realizes light emission by receiving the exciton energy formed in the host.

[0103] The light-emitting part can be derived from a light-emitting material (referred to as a light-emitting compound in this specification) that can emit light through the movement of electrons in an organic light-emitting diode.

[0104] The light-emitting compound (light-emitting material) can be a compound commonly used as a dopant in an organic light-emitting diode. A dopant capable of achieving the desired color can be selected according to the purpose as the light-emitting compound, and thereby the light-emitting part is induced.

[0105] In one example, the light-emitting part can have a conjugated structure with a quantum efficiency of more than 50% in the visible light wavelength range of 400 nm to 700 nm.

[0106] 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%.

[0107] 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.

[0108] 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. The premise is that the organometallic compound that induces the luminescent portion is a luminescent substance that can emit light.

[0109] 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.

[0110] The light-emitting portion may contain carbon and hydrogen (wherein the definition of hydrogen includes deuterium and tritium, i.e., the light-emitting portion may include 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.

[0111] Specific examples of the luminescent compound (or luminescent material) may include the following compounds, but are not limited thereto.

[0112]

[0113]

[0114] 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.

[0115] 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.

[0116] 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.

[0117] In one example, the luminescent compound and the luminescent part may include a conjugated structure that forms a HOMO or LUMO wave function, and the conjugated structure may contain boron.

[0118] The luminescence mechanism of the luminescent part may include fluorescence that emits light from a singlet state, phosphorescence that emits light from a triplet state, and delayed fluorescence that emits light due to energy transfer from a triplet state to a singlet state.

[0119] As described above, the composite luminescent compound can be designed by connecting an electron-regulating part to the luminescent compound through a linking group.

[0120] When an electron-regulating compound induced by the electron-regulating part is connected to the luminescent compound through a connecting part to form the composite luminescent compound, substituents and the like contained in the luminescent compound or the electron-regulating compound can be appropriately modified so that chemical bonding is formed between these parts or with the connecting part, thereby inducing the luminescent part and the electron-regulating part. At this time, the modifying part for chemical bonding does not significantly change the luminescence characteristics, bandgap energy, energy efficiency, etc. that are unique to the electron-regulating compound and the luminescent compound respectively. For example, when a substituent in the luminescent compound is replaced by another substituent for forming a chemical bond, although the luminescent part can be formed, the luminescence characteristics, bandgap energy, energy efficiency, etc. of the luminescent part are not significantly affected by the replacing substituent.

[0121] The "not being significantly affected" means not departing from the detailed description of the electron-regulating part and the luminescent part described in this specification. Specifically, the "appropriate" modification of the substituents of the electron-regulating compound and the luminescent compound during the chemical bonding process means that the obtained composite luminescent compound conforms to the description in this specification. That is, it means that by modifying the substituents to achieve the general substituent effect of changing the bandgap of the luminescent compound or improving the quantum efficiency, it means that there will be no drastic change that causes a reduction of more than 80% in the bandgap energy, efficiency, etc.

[0122] In one example, the bandgap energy of the electron-regulating part may be from 1 eV to 4.7 eV, and the bandgap energy of the luminescent part may be from 0.5 eV to 3.5 eV.

[0123] The electron - regulating part of the composite light - emitting compound does not significantly affect the unique light - emitting characteristics of the light - emitting part, while achieving the charge balance of holes and electrons inside the light emission, thereby improving the light - emitting efficiency and the stability of the device. In addition, the electron - regulating part maintains a spatial position and an angle that do not chemically interact with the light - emitting part, while protecting specific parts of the light - emitting part, thereby significantly reducing the probability of chemical interactions and Coulomb interactions with other surrounding dopant substances, host substances, and excitons.

[0124] For the above reasons, the composite light - emitting compound can improve the light - emitting stability when driving an organic light - emitting diode device.

[0125] In one example, the composite light - emitting compound can be any one of the following compounds.

[0126]

[0127]

[0128]

[0129]

[0130]

[0131] The compound has a structure in which the electron - regulating part and the 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 the spiro atom.

[0132] In one example, the light - emitting layer further contains a host, and the LUMO energy level of the electron - regulating part is lower than the LUMO energy level of the host.

[0133] The host can be a well - known substance, that is, a host substance that can generally form a light - emitting layer.

[0134] For example, the light - emitting layer can be composed only of the composite light - emitting compound and the host.

[0135] In one example, the host can include at least one or more. When the light - emitting layer contains two or more hosts, the LUMO energy level of the electron - regulating part is lower than the LUMO energy level of at least one of the two or more hosts. Therefore, when there are two or more hosts, the LUMO energy level of the host with the lowest LUMO energy level among the two or more hosts is compared with the LUMO energy level of the electron - 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, this secondary - light - emitting substance does not belong to the host. The secondary - light - emitting substance can be an additional dopant described below.

[0136] In one example, the light-emitting layer may include at least two of the composite light-emitting compounds.

[0137] In one example, the composite light-emitting compound may include at least two or more of the electron-regulating portions.

[0138] Specifically, the composite light-emitting compound may include more than two electron-regulating portions connected to one light-emitting portion. In this case, the composite light-emitting compound also forms two connecting portions, where each electron-regulating portion is connected to the light-emitting portion.

[0139] In one example, the light-emitting layer may include at least two of the electron-regulating portions. For example, when there are two of the electron-regulating portions in the light-emitting layer, the two electron-regulating portions may also be present in one composite light-emitting compound, and each molecule in a plurality of identical or different composite light-emitting compounds may include a different electron-regulating portion. For example, when one composite light-emitting compound includes at least two electron-regulating portions, each electron-regulating portion may be the same or different. For example, when the light-emitting layer includes more than one composite light-emitting compound, the electron-regulating portions included in each molecule of the composite light-emitting compound may be the same or different.

[0140] When there are more than two electron-regulating portions in the light-emitting layer, the LUMO energy levels of all the electron-regulating portions are lower than the LUMO energy level of the host. For example, when there are more than two electron-regulating portions, the LUMO energy levels of all the more than two electron-regulating portions are compared with the LUMO energy level of the host.

[0141] When there are more than two electron-regulating portions in the light-emitting layer and there are more than two hosts, the LUMO energy levels of all the electron-regulating portions present in the light-emitting layer are lower than the LUMO energy level of at least one host. That is, the LUMO energy levels of all types of electron-regulating portions present in the light-emitting layer are higher than the LUMO energy level of the host of the type with the highest LUMO energy level among the host types.

[0142] The light-emitting layer may further include an additional dopant. The role of the additional dopant is to absorb the light-emitting energy of the light-emitting portion and re-emit it. Therefore, the maximum light-emitting wavelength energy of the additional dopant is less than the maximum light-emitting wavelength energy of the light-emitting portion. By using the additional dopant, low-energy light emission can be obtained.

[0143] The maximum light-emitting wavelength energy refers to the wavelength with the maximum photon energy in the light-emitting spectrum. The maximum light-emitting wavelength is calculated from the onset value at the start position of the light emission, and the maximum light-emitting wavelength is calculated from the wavelength with the maximum light-emitting intensity.

[0144] The detailed description of the additional dopant compound is the same as that of the luminescent compound (or luminescent substance) that induces the luminescence of the luminescent part. For example, the additional dopant can be a known dopant or luminescent substance.

[0145] In one example,

[0146] The luminescent layer may contain 0.1 mol% to 100 mol%, for example, 0.1 mol% to 50 mol% of the composite luminescent compound, but is not limited thereto.

[0147] In one example, the molar ratio of the composite luminescent compound to the host in the luminescent layer can be 1:1.01 to 1000, specifically, 1:1.01 to 100.

[0148] In one example, the molar ratio of the composite luminescent compound to the additional dopant in the luminescent layer can be 1:0.01 to 1, specifically, 1:0.01 to 0.1.

[0149] In one example, the composite luminescent compound may contain at least one deuterium.

[0150] In the organic light-emitting diode, the luminescent layer may further contain a phosphorescent substance to further improve the luminescence efficiency of the luminescent layer.

[0151] In one example, the luminescent layer may further contain a phosphorescent substance containing Pt or Ir.

[0152] The compound represented by the following structural formula is an example of an organometallic compound commonly used as a phosphorescent substance.

[0153]

[0154] In the formula, each R can be a C1-20 alkyl group, a C3-20 cycloalkyl group, a C2-20 heterocycloalkyl group, a C6-30 aryl group, etc.

[0155] In the organic light-emitting diode, the luminescent layer may further contain a delayed fluorescence substance to further improve the luminescence efficiency of the luminescent layer.

[0156] In one example, the luminescent layer may further contain a delayed fluorescence substance with an energy difference between the singlet state and the triplet state of 0.3 eV or more.

[0157] The compound represented by the following structural formula is an example of a commonly used delayed fluorescence substance.

[0158]

[0159] In the formula, Ar may be a C1-20 alkyl group, a C3-20 cycloalkyl group, a C2-20 heterocycloalkyl group, a C6-30 aryl group, etc., respectively.

[0160] The organic light-emitting diode may include, as an organic layer, 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 combinations thereof.

[0161] In one example, the organic light-emitting diode may sequentially include an anode, a hole injection layer (HIL: hole injection layer), a hole transport layer (HTL: hole transport layer), a light-emitting layer (EML, light emitting layer), an electron transport layer (ETL: electron transport layer), and a cathode.

[0162] The organic light-emitting diode may be a tandem organic light-emitting diode including a plurality of organic light-emitting units.

[0163] A plurality of organic light-emitting units may be sequentially stacked, and a charge generation layer (charge generation layer, CGL) may be included between the organic light-emitting units. The charge generation layer is located between the organic light-emitting units to evenly distribute charges to the light-emitting layers of the respective organic light-emitting units.

[0164] The tandem organic light-emitting diode includes a light-emitting layer, and at least one of the organic light-emitting units contains the above-mentioned composite functional compound.

[0165] In the tandem organic light-emitting diode, the detailed description of the composite functional compound is as described above.

[0166] (Example)

[0167] Synthesis Example

[0168] Synthesis of Comparative Compound 1

[0169]

[0170] 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 a 2.5 M n-butyllithium solution (in hexane) was added, and the mixture was stirred at room temperature for 3 hours.

[0171] Then, the reactants were cooled to 0 °C again. After adding 1.90 mL of boron tribromide (20.0 mmol), the mixture was stirred at room temperature for 0.5 hour. The reactants were cooled to 0 °C again. After adding 3.51 mL of N,N-diisopropylethylamine (20.0 mmol), the mixture was stirred at 60 - 70 °C for 2 hours.

[0172] The reaction solution was cooled to room temperature, and the organic layer was extracted with ethyl acetate. The solvent of the extracted organic layer was dried with MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography (DCM / hexane).

[0173] Then, recrystallization was carried out with a DCM / acetone mixed solvent to obtain 1.05 g of the comparative compound 1, with a yield of 12%.

[0174] MS(ACPI) m / z: 779 [M+H]

[0175] NMR: δH (500 MHz; CDCl3; Me4Si) 8.94 (s, 1H), 8.84 (d, J = 10 Hz, 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, 3H), 7.19 (d, 1H), 6.67 (s, J = 8 Hz, 2H), 6.15 (d, 1H), 6.06 (s, 1H), 1.89 (s, 3H), 1.64 (d, 4H), 1.46 (s, 20H), 1.37 (s, 11H), 1.25 (s, 3H), 1.22 (s, 10H).

[0176] Synthesis of Compound 2

[0177]

[0178] Compound 2-1 of the present invention (11.41 g, 10.0 mmol) was dissolved in mesitylene (45 ml) and cooled to -30 °C. Under a nitrogen atmosphere, 2.5 M n-butyllithium solution (in hexane) (8.0 mL, 20.0 mmol) was added, and the mixture was stirred at -30 °C for 30 hours.

[0179] Then, the reactants were cooled to -30 °C again. After adding boron tribromide (1.90 mL, 20.0 mmol), the mixture was stirred at room temperature for 2 hours. 2,6-Di-tert-butylpyridine (2.18 mL, 10.0 mmol) was added at room temperature and the mixture was stirred at 170 °C for 8 hours.

[0180] The reaction solution was cooled to room temperature, and the organic layer was extracted with ethyl acetate. The solvent of the extracted organic layer was dried with MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography (DCM / hexane).

[0181] Then, recrystallization was performed with a DCM / acetone mixed solvent to obtain 0.75 g of the said Compound 2 with a yield of 7%.

[0182] MS(ACPI) m / z: 1071 [M+H]

[0183] NMR: δH(400 MHz; CDCl3; Me4Si) 9.20 (dd, J = 7.7, 2.7 Hz, 1H), 9.00 - 8.81 (m, 2H), 8.74 - 8.63 (m, 3H), 7.97 (dddd, J = 41.1, 34.8, 16.0, 4.6 Hz, 4H), 7.77 - 7.63 (m, 3H), 7.62 - 7.28 (m, 12H), 7.17 - 6.85 (m, 10H), 6.83 - 6.34 (m, 8H), 6.04 - 5.83 (m, 3H), 2.36 (s, 3H), 2.13 (s, 3H).

[0184] Synthesis of Compound 3

[0185]

[0186] Synthesis was carried out in the same manner as Compound 2 above, except that Compound 3-1 of the present invention was used in the same molar ratio instead of Comparative Compound 2-1.

[0187] Thereafter, 0.54 g of Compound 3 was obtained with a yield of 5%.

[0188] MS(ACPI) m / z: 1071 [M+H]

[0189] NMR: δH(400 MHz; CDCl3; Me4Si) 9.25 - 9.07 (m, 2H), 8.93 - 8.77 (m, 5H), 8.62 - 8.43 (m, 1H), 8.10 - 7.87 (m, 2H), 7.81 - 7.56 (m, 10H), 7.54 - 7.27 (m, 6H), 7.17 - 6.59 (m, 15H), 6.46 (ddd, J = 7.1, 5.6, 4.2 Hz, 2H), 6.07 - 5.95 (m, 2H), 5.96 - 5.87 (m, 1H), 2.36 (s, 3H), 2.15 (d, J = 2.1 Hz, 3H).

[0190] Experimental Example 1. Measurement of HOMO-LUMO Energy Levels

[0191] Under the condition of DMF solution, differential pulse voltammetry (DPV) analysis was carried out on p-HOST, Compound 2 and Compound 3, and the results are shown in Table 1 below. It can be seen from this that the LUMO energy level of p-HOST is lower than that of the electron regulation part.

[0192] The measuring instrument used was an Autolab Electrochemical Workstations PGSTAT101 potentiostat / galvanostat.

[0193]

Table 1

[0194]

[0195] Fabrication of Organic Light-Emitting Diodes

[0196] The ITO surface was treated with ultraviolet ozone for 3 minutes under normal pressure.

[0197] The device was processed in a 10 -7 torr vacuum chamber in the following order.

[0198]

[0199] p-HOST

[0200] Comparative Example 1 (Device 1)

[0201] HATCN was deposited as a hole injection material to a thickness of

[0202] Compound A was deposited as a hole transport material to a thickness of

[0203] Compound B was deposited as an electron blocking layer to a thickness of

[0204] Using HOST-1 as the light-emitting layer, doped with Comparative Compound 1 (5 mol%), deposited to a thickness of

[0205] Compound C was deposited as a hole blocking layer to a thickness of

[0206] A 1:1 ratio of Compound D and LiQ was deposited as an electron transport layer to a thickness of

[0207] LiQ was deposited as an electron injection layer to a thickness of

[0208] Al was deposited as an electrode to a thickness of

[0209] Comparative Example 2 (Device 2)

[0210] It was fabricated in the same manner as Comparative Example 1, except that Comparative Compound 1 (10 mol%) was doped in the light-emitting layer of Device 1.

[0211] Example 1 (Device 3)

[0212] It was fabricated in the same manner as Comparative Example 1, except that 10 mol% of Compound 2 was doped in the light-emitting layer of Device 1 instead of Comparative Compound 1.

[0213] Example 2 (Device 4)

[0214] It was fabricated in the same manner as Comparative Example 1, except that 10 mol% of Compound 3 was doped in the light-emitting layer of Device 1 instead of Comparative Compound 1.

[0215] Hereinafter, an analysis will be made based on the maximum luminous efficiency of each device.

[0216]

Table 2

[0217]

[0218] As can be seen from the above table, the devices using the compounds of the present invention exhibit excellent luminous efficiency and improved driving voltage characteristics. The hole transfer of the host material used in device fabrication is superior to electron transfer. Specifically, when Comparative Compound 1 was doped, electron injection was difficult, so the energy transfer effect to the dopant was poor, resulting in an external quantum efficiency of only 5.17% and 5.92%. However, when an electron-regulating moiety (e.g., Compounds 2 and 3) was introduced, electrons were easily injected into the electron-regulating moiety, thereby increasing the density in the light-emitting layer and obtaining maximum quantum efficiencies of 14.0% and 15.7%, respectively.

[0219] Although the present invention has been described with reference to the above exemplary drawings, 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 explaining the embodiments of the present invention, the effects foreseeable by this configuration should also be recognized.

Claims

1. An organic light-emitting diode, characterized in that, Comprising a first electrode, a second electrode, and a light-emitting layer located between the first electrode and the second electrode, The light-emitting layer contains a composite light-emitting compound, The composite light-emitting compound contains an electron-regulating portion and a light-emitting portion, The composite light-emitting compound contains a linking portion that connects the electron-regulating portion and the light-emitting portion through a spiro bond, The electron-regulating portion is a substituted or unsubstituted C6-50 aromatic ring or C5-50 aromatic hetero condensed ring, or an organometallic compound derived from its combination with a metal, The HOMO-LUMO energy gap energy of the electron-regulating portion is greater than the maximum emission wavelength energy of the light-emitting portion, The LUMO energy level of the electron-regulating portion is equal to or lower than the LUMO energy level of the light-emitting portion.

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

3. The organic light emitting diode according to claim 1, characterized in that, The light-emitting portion has a conjugated structure with a quantum efficiency of more than 50% in the visible light wavelength range of 400nm to 700nm.

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

5. The organic light emitting diode according to claim 1, characterized in that, The light-emitting mechanism of the light-emitting portion includes fluorescence emitted from a singlet state, phosphorescence emitted from a triplet state, and delayed fluorescence emitted by energy transfer from a triplet state to a singlet state.

6. The organic light-emitting diode according to claim 1, wherein, The light-emitting layer further contains a host, The LUMO energy level of the electron-regulating portion is lower than the LUMO energy level of the host.

7. The organic light emitting diode according to claim 1, wherein, The composite light-emitting compound contains at least one deuterium.

8. 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.

9. The organic light emitting diode according to claim 1, wherein, The electron-regulating portion and the light-emitting portion form the linking portion through a spiro bond, and the change in their HOMO energy level, LUMO energy level, or HOMO-LUMO band gap energy does not exceed 0.2eV.

10. The organic light-emitting diode according to claim 1, wherein The light-emitting portion is a C6-50 aromatic ring, a C5-50 aromatic hetero condensed ring, or an organometallic compound derived from its combination with a metal.

11. The organic light-emitting diode according to claim 1, characterized in that, The light-emitting portion includes a conjugated structure that forms a HOMO or LUMO wave function, and the conjugated structure contains boron.

12. The organic light-emitting diode according to claim 1, wherein, The electron-regulating portion is a C6-50 aromatic ring having at least one substituent represented by the structure of Formula 1 below; or a C5-50 aromatic hetero condensed ring having at least one substituent represented by Formula 1 below, Formula 1: In Formula 1, L is a single bond, or a divalent group selected from the group consisting of: C1-30 alkylene, C3-30 cycloalkylene, C2-30 hetero cycloalkylene, C1-30 alkylmethylsilylene, C3-30 cycloalkylmethylsilylene, C2-30 hetero cycloalkylmethylsilylene, C1-30 arylmethylsilylene, C7-30 alkylarylmethylsilylene, C9-30 cycloalkylarylmethylsilylene, C8-30 hetero cycloalkylarylmethylsilylene, oxygen, sulfur, a divalent group of C6-30 arylphosphine, a divalent group of C6-30 arylphosphine oxide, C6-30 arylene, C2-30 hetero arylene, and combinations thereof, t is an integer from 0 to 5, v is 0 or 1, each of R" is independently selected from hydrogen, deuterium, C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl optionally substituted with a third additional substituent, C2-30 heteroaryl optionally substituted with a third additional substituent, C1-30 alkylamino, C3-30 cycloalkylamino, C2-30 heterocycloalkylamino, C6-30 arylamino optionally substituted with a third additional substituent, C7-30 alkylarylamino optionally substituted with a third additional substituent, C9-30 cycloalkylarylamino optionally substituted with a third additional substituent, C8-30 heterocycloalkylarylamino optionally substituted with a third additional substituent, halogen, CN, C1-30 alkoxy, C6-30 aryloxy optionally substituted with a third additional substituent, C1-30 alkylsilyl optionally substituted with a third additional substituent, C3-30 cycloalkylsilyl optionally substituted with a third additional substituent, C2-30 heterocycloalkylsilyl optionally substituted with a third additional substituent, C6-30 arylsilyl optionally substituted with a third additional substituent, C7-30 alkylarylsilyl optionally substituted with a third additional substituent, C9-30 cycloalkylarylsilyl optionally substituted with a third additional substituent, C8-30 heterocycloalkylarylsilyl optionally substituted with a third additional substituent, C1-30 alkylthio, C3-30 cycloalkylthio, C2-30 heterocycloalkylthio, C6-30 arylthio, C1-30 arylphosphine, C1-30 arylphosphine oxide, and combinations thereof, provided that at least two of the R" can be connected to each other to form a ring, the third additional substituent is selected from C1-30 alkyl, C3-30 cycloalkyl, C2-30 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl, C2-30 heteroaryl, C2-30 alkylamino, C3-30 cycloalkylamino, C2-30 heterocycloalkylamino, C7-30 alkylarylamino, C9-30 cycloalkylarylamino, C8-30 heterocycloalkylarylamino, C1-30 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, each of Y is independently nitrogen, oxygen, sulfur, or carbon, Indicates the connection part.

13. The organic light emitting diode according to claim 12, wherein, the substituent represented by the structure of Formula 1 is represented by any one of the structures of Formulae D-1 to D-13 below, in Formulae D-1 to D-13, each of X'" is independently oxygen, nitrogen, sulfur, or selenium, R'" are each independently selected from hydrogen, deuterium, C1-30 alkyl, C3-20 cycloalkyl, C2-20 heterocycloalkyl, C3-30 alkenyl, C6-30 aryl, C2-30 heteroaryl, C2-30 alkylamino, C3-20 cycloalkylamino, C2-20 heterocycloalkylamino, halogen, CN, C1-30 alkylsilyl, C3-20 cycloalkylsilyl, C2-20 heterocycloalkylsilyl, C6-30 arylsilyl, and combinations thereof, u is each independently an integer from 0 to 20, The dashed line indicates the connecting portion.

14. The organic light-emitting diode according to claim 1, wherein The light-emitting layer contains at least two of the composite light-emitting compounds.

15. The organic light-emitting diode according to claim 1, characterized in that, The composite light-emitting compound contains at least two of the electron-regulating portions.

16. The organic light-emitting diode according to claim 1, wherein The light-emitting layer further contains an additional dopant.

17. The organic light emitting diode according to claim 1, characterized in that, The light-emitting layer further contains a phosphorescent material containing Ir or Pt.

18. The organic light-emitting diode according to claim 1, wherein The light-emitting layer further contains a delayed fluorescence material having a singlet-triplet energy difference of 0.3 eV or more.

19. The organic light-emitting diode according to claim 1, wherein The organic light-emitting diode is a tandem organic light-emitting diode including a plurality of organic light-emitting units, At least one of the plurality of organic light-emitting units includes the light-emitting layer.

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