A novel nitrogen-containing cyclic compound and device

Abstract

The invention discloses a novel nitrogen-containing cyclic compound and a device. The nitrogen-containing cyclic compound has a specific structural formula, and R1 and R2 have multiple optional groups. The devices include electronic devices, hole devices and organic light-emitting diode devices, all of which include the same first electrode (anode) and second electrode (cathode) and a functional thin film layer, and the functional thin film layer includes the above-mentioned nitrogen-hybridized cyclic compound. In the invention, the organic cyclic π-conjugated compound skeleton has a strong electron transfer ability and outstanding photoelectric performance. The compound has a bipolar structure, which is conducive to the transmission and recombination of electrons and holes, can improve the luminous efficiency of the device, reduce intermolecular forces and π-π stacking, improve solubility, reduce the device start-up voltage, and regulate the luminous color. The photophysical properties of related materials and the preparation and performance of different devices are demonstrated through embodiments.

Description

Technical Field

[0001] The invention relates to the technical field of organic materials and electroluminescent devices, in particular to a novel nitrogen-containing cyclic compound and a device. Background Art

[0002] OLED is an organic light emitting diode (OLED), which uses the property of organic materials to emit light when current is passed through them. The structure of OLED devices can be active or passive, and thin film transistors (TFTs) are used in active devices to control the current. Unlike traditional liquid crystal displays (LCDs), OLEDs do not require a backlight, so they can be thinner, lighter, have higher contrast, faster response, wider viewing angle, and lower power consumption. Therefore, they are widely used in display technology and are regarded as one of the most promising products in the 21st century.

[0003] The basic structure of an OLED device includes a transparent conductive ITO (indium tin oxide) electrode, a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), etc. The structure of an OLED includes a transparent conductive layer as an anode, a conductive layer as a cathode, and an organic light-emitting material layer between the two. After the organic light-emitting material is injected with charges, electrons and holes (in semiconductor physics, the vacancies left in the valence band after the electrons in the valence band gain energy and transition to the conduction band) recombine to emit light. In recent years, the performance of OLED devices has been significantly improved by regulating the molecular structure of materials, optimizing device structure and processes, and introducing new materials and technologies. In particular, new materials meet consumers' new demands for display technology. The key to optimizing OLED devices is to improve the luminous efficiency of materials, charge injection balance and stability, and reduce the power consumption of devices.

[0004] The existing patent with authorization announcement number CN111018872B discloses a nitrogen-containing cyclic compound and a method for preparing a device thereof, an organic electroluminescent material containing the same, a light-emitting layer and an application thereof. The invention provides a nitrogen-containing cyclic compound as a main material, which has a high luminous efficiency and is beneficial to improving the overall performance of the device when used in an OLED device.

[0005] At present, the photophysical properties of the ring structure of biphenyls connected end to end are more outstanding than those of the linear biphenyl structure commonly used in OLEDs. It has similar properties to carbon nanotubes, inhibits the π-π stacking of the linear biphenyl structure, and improves its solubility. This new type of carbon nanoring structure has good photophysical properties; therefore, the present invention proposes a new type of nitrogen-containing cyclic compound and device. Summary of the invention

[0006] The object of the present invention is to provide a novel nitrogen-containing cyclic compound and device to solve the problems raised in the above background.

[0007] Among them, the present invention relates to an organic material containing an indolecarbazole macrocycle, which can be used for a light-emitting device or an electroluminescent device, in particular an organic light-emitting diode, wherein the device comprises a light-emitting layer and at least two electrodes; the present invention also relates to a device comprising the electronic device, hole device and / or OLED;

[0008] At the same time, in order to achieve the above-mentioned purpose, the present invention provides the following technical solution: the nitrogen-containing cyclic compound (indolecarbazole macrocyclic organic material) has a structure shown in the following structural formula I;

[0009]

[0010] wherein R1 is independently selected from hydrogen, substituted or unsubstituted C1 to C 30 Alkyl (straight or branched saturated hydrocarbon group consisting of 1 to 30 carbon atoms), substituted or unsubstituted C1-C 30 heteroatoms (N, S, O, P, Se, Si, B, etc.) alkyl chains; R2 is independently selected from hydrogen, halogen, substituted or unsubstituted C1~C 30 Alkyl, substituted or unsubstituted C4~C 30 Arylalkyl, substituted or unsubstituted C6~C 30 hetero (N, S, O, P, Se, Si, B, etc.) aromatic group, and R2 symmetrically replaces the 1st, 2nd or all positions of the benzene ring;

[0011] Alkyl refers to different saturated alkyl chains R1 or R2, "heteroatom alkyl" refers to different saturated alkoxy chains R1 or R2, or alkyl chains R1 or R2 with -CN, -N3, NH2, etc. Its main goal is to increase the solubility of the molecule; in "aralkyl", alkyl refers to different saturated alkyl chains, and aryl mainly refers to benzene ring, naphthalene, anthracene, pyrene, phenanthrene, etc.; in "heterocyclic aralkyl", alkyl refers to different saturated alkyl chains, and "hetero" includes Si, B, N, O, S, P; heteroaryl mainly refers to furan, thiophene, imidazole, carbazole, pyrrole, thiazole, pyrimidine, pyrazole, triazole, etc.; the main goal of alkyl is to increase its solubility;

[0012] The structure of R2 is substituted, in addition to hydrogen, halogen and alkyl, and also has the following structure:

[0013]

[0014] The structure replacing the R2 may be a condensed ring conjugated with a benzene ring (structural formula II), including a condensed ring substituted with a heteroatom;

[0015]

[0016] Wherein, R1 is independently selected from hydrogen, substituted or unsubstituted C1-C 30 Alkyl, substituted or unsubstituted C1~C 30 Heteroatom alkyl chain, etc.; X1 or X2 is independently selected from substituted or unsubstituted heteroatoms (N, S, O, B, etc.) and C atom aryl moieties;

[0017] In the group R2, "arylalkyl" includes at least one planar conjugated system in addition to the alkyl chain R1. "Heterocyclic arylalkyl" includes at least one heterocyclic conjugated structure, including an aromatic conjugated structure and the alkyl chain R1; in "heteroatom alkyl", the oxygen atom in the alkyl group is at any position in the alkyl group, among which -CN, -N3, -OH, NH2, etc. are generally considered to be terminal groups.

[0018] Preferably, the device comprises an electronic device, a hole device and an organic light emitting diode device; the electronic device, the hole device and the organic light emitting diode device all comprise the same first electrode (anode) and second electrode (cathode).

[0019] Preferably, the electronic device comprises an organic material layer between the first electrode and the second electrode, and the electronic device structure is as follows: Fig.11 As shown in the figure, 1 is an ITO anode; 2 is an electron transport layer; 3 is a light-emitting functional layer; 4 is a hole blocking layer; 5 is an electron transport layer; 6 is a cathode; 7 is a covering layer; the organic material layer in the electronic device includes an electron transport layer and a hole blocking layer, each with at least one layer.

[0020] Preferably, the hole device comprises an organic material layer between the first electrode and the second electrode, and the hole device structure is as follows: Fig.12 As shown in the figure, 1 is an ITO anode; 2 is a hole injection layer (hole transport layer); 3 is a hole transport layer; 4 is a light-emitting functional layer; 5 is a hole transport layer; 6 is a cathode; 7 is a covering layer, and the organic material layer in the hole device includes a hole injection layer and a hole transport layer, at least one layer.

[0021] Preferably, the organic light emitting diode device comprises an organic material layer between the first electrode and the second electrode, and the structure of the organic light emitting diode device is as follows: Fig.13 As shown in the figure, 1 is an ITO anode; 2 is a hole injection layer (hole transport layer); 3 is a hole transport layer; 4 is a light-emitting functional layer; 5 is a hole blocking layer; 6 is a cathode; 7 is a covering layer, and the organic material layer in the organic light-emitting diode device includes an electron transport layer and a hole blocking layer, each with at least one layer.

[0022] Preferably, the thickness of the electron transport layer and the hole blocking layer in the electronic device is 1 nm to 600 nm.

[0023] Preferably, the thickness of the hole injection layer and the hole transport layer in the hole device is 1 nm to 600 nm.

[0024] Preferably, the thickness of the electron transport layer and the hole blocking layer in the organic light emitting diode device is 1 nm to 600 nm.

[0025] Preferably, the anode material of the device is selected from one or more combinations of metals (such as gold, silver, copper, iron, chromium, nickel, manganese, palladium, platinum, etc. and their alloys), metal oxides (such as indium oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc.), conductive polymers (such as polyaniline, polypyrrole, poly(3-methylthiophene), PVK (poly(9-vinylcarbazole)), PEDOT:PSS (poly(3,4-ethylenedioxythiophene-polyethylene sulfonic acid), CBP (4,4'-di(9-carbazole)biphenyl), etc.).

[0026] Preferably, the cathode material of the device may be a metal layer (for example, aluminum, magnesium, silver, indium, tin, titanium, etc. and alloys thereof), a metal layer, a single layer containing a metal oxide, a single layer containing one of the metal halides, a composite layer of several, or a combination of multiple single layers, a single layer and a composite layer (for example, LiF / Al, LiO2 / Al, BaF2 / Al, etc.).

[0027] The OLED device is manufactured by a method known in the art; the manufacturing method includes: forming an anode on a transparent or opaque smooth substrate, forming multiple organic thin film layers on the anode, and forming a cathode on the organic thin film layers. Each film layer, including the functional light-emitting layer, can be formed by known film forming methods such as evaporation, vacuum deposition, sputtering, spin coating, dipping, ion plating, casting, LB method, etc.

[0028] The beneficial effects of the present invention are as follows:

[0029] In the technical solution of the present application, compared with linear aromatic conjugation, the skeleton of the organic cyclic π conjugated compound has a strong electron transfer ability and more outstanding photoelectric performance; and the group with electronic ability is connected to the cyclic skeleton, so that the compound has a bipolar structure, which is conducive to the transmission and recombination of electrons and holes. The introduction of groups in the macrocycle increases the electron transfer channel of the macrocycle, which can improve the luminous efficiency of the device having it; at the same time, the structure can reduce the intermolecular force and reduce the intermolecular π-π stacking; introduce flexible functional groups to improve the solubility of molecules, improve the solubility of luminescent functional films, and reduce defects in the film; carbon nanorings are ultra-short structures of carbon nanotubes and have the performance of carbon nanotubes. In addition, organic compounds can also reduce the turn-on voltage of the device, and the turn-on voltage is also affected by the modified functional groups, which can adjust the luminous color of OLED devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of organic light-emitting materials;

[0031] Figure 2 It is a schematic diagram of the structure of an electronic device;

[0032] Figure 3 is a schematic diagram of the structure of a hole device;

[0033] Figure 4 is a schematic diagram of the structure of an organic light emitting diode device;

[0034] Figure 5 J for electronic devices with luminescent materials 1 / 2 -V and fitting curve;

[0035] Figure 6 J of hole devices with luminescent materials 1 / 2 -V and fitting curve;

[0036] Figure 7 This is the OLED device structure and energy level diagram of the light-emitting material in Case 1;

[0037] Figure 8 For J 1 / 2 -V curve and luminous color of OLED devices;

[0038] Fig. 9 The relationship between voltage and brightness and the physical picture of OLED device;

[0039] Fig.10 is the relationship between voltage and external quantum efficiency;

[0040] Fig.11 It is a schematic diagram of the structure of the electronic device;

[0041] Fig.12 Schematic diagram of the hole device structure;

[0042] Fig.13 is a schematic diagram of the structure of an organic light emitting diode device; DETAILED DESCRIPTION

[0043] The present invention mainly relates to a novel nitrogen-heterocyclic compound and devices based on the molecule, including electronic devices, hole devices and organic light-emitting diode devices (OLED); the present application is further described in detail in conjunction with the embodiments below;

[0044] Embodiment 1:

[0045] like Figure 1As shown, an organic light-emitting material ICZ

[10] CPP, R1 is H, R2 is tert-butyl, and the substitution position is 1. In tetrahydrofuran, its UV-Vis absorption wavelength is 330nm and its fluorescence wavelength is 520nm; the fluorescence quantum efficiency of 2,8-di-tert-butyl-5,11-dihydroindole[3,2-b]carbazole is only 0.01, but after conjugation with a macrocyclic structure, its photoluminescence quantum efficiency is 0.92. This material has good photoelectric properties.

[0046] Case 2:

[0047] In the present invention, the relevant photophysical properties based on structural formula I are only exemplified here, as shown in the following table;

[0048]

[0049] Example 3

[0050] In the present invention, based on the relevant photophysical properties of the light-emitting material in Example 1, an electronic device is provided; the electronic device comprises an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode, and the material of the organic thin film layer comprises the above-mentioned organic compound; the material of the organic thin film layer may be one or more of the above-mentioned organic compounds, and may also comprise a mixture of two or more of the above-mentioned organic compounds;

[0051] The preparation method of the electronic device of the present invention comprises the following steps: cleaning 20 mm×20 mm ITO in ethanol and acetone solvents respectively, and drying the ITO in an inert atmosphere for standby use; depositing SnO2 on the ITO; dissolving the product (luminescent layer) and performing spin coating, and annealing the luminescent layer to remove the solvent; vacuum depositing TBPi, Liq, and Al on the film respectively to prepare an OLED device; and finally obtaining an LED luminescent effective area of ​​2×2 mm 2 Its electronic devices such as Figure 2 As shown, ITO refers to the first electrode, SnO2 refers to the electron transport layer, ICZ

[10] CPP refers to the light-emitting functional layer, TBPi refers to the hole blocking layer, Liq refers to the electron transport layer, and Al refers to the second electrode:

[0052] In the present invention, the organic electronic device is as follows:

[0053] The invention comprises: a first electrode (ITO); an electron transport layer (SnO2, tin dioxide), wherein the organic light-emitting functional layer is on the first electrode; an organic light-emitting functional layer (ICZ

[10] CPP), which is on the electron transport layer; a hole blocking layer (TBPi, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), which is on the organic light-emitting functional layer; an electron transport layer (Liq, 8-hydroxyquinoline lithium), which is on the hole blocking layer; a second electrode, which is on the electron transport layer; the organic light-emitting functional layer comprises a light-emitting layer; the light-emitting layer comprises the organic photoelectric compound as described above;

[0054] like Figure 5 As shown, through J 1 / 2 -V curves obtained electron (μe) mobility of 4.46×10 -7 cm 2 ·V -1 ·S -1 .

[0055] Example 4

[0056] In the present invention, based on the relevant photophysical properties of the light-emitting material in Case 1, a hole device is provided, the hole device comprises an anode, a cathode and an organic thin film layer arranged between the anode and the cathode, the material of the organic thin film layer comprises the above-mentioned organic compound; the material of the organic thin film layer may be one of the above-mentioned organic compounds, or may comprise a mixture of two or more of the above-mentioned organic compounds;

[0057] The preparation method of the hollow hole device device of the present invention comprises the following steps: cleaning 20 mm×20 mm ITO in ethanol and acetone solvents respectively, and drying the ITO in an inert atmosphere for standby use; then spin coating the Pedot:PSS layer and the PVK layer on the ITO, and then heating and annealing are performed respectively after completion; the product (luminescent layer) is dissolved and spin coated, and the luminescent layer is also annealed to remove the solvent; MoO3 and Ag are vacuum deposited on the film respectively to prepare a hollow hole device; and finally, an LED with an effective luminescent area of ​​2×2 mm is obtained. 2 ; Its hole devices such as Figure 3 As shown, ITO refers to the first electrode, PEDOT refers to the hole injection layer, PVK refers to the hole transport layer, ICZ

[10] CPP refers to the organic light-emitting functional layer, MoO3 refers to the hole transport layer, and Ag refers to the second electrode:

[0058] In the present invention, the organic hole device is as follows:

[0059] The invention comprises: a first electrode (ITO); a hole injection layer (PEDOT, poly 3,4-ethylenedioxythiophene), which is on the first electrode; a hole transport layer (PVK), which is on the hole injection layer; an organic light-emitting functional layer (ICZ

[10] CPP), which is on the hole transport layer; a hole transport layer (MoO3, molybdenum trioxide), which is on the organic light-emitting functional layer; a second electrode, which is on the hole transport layer; the organic light-emitting functional layer comprises a light-emitting layer; the light-emitting layer comprises the organic photoelectric compound as described above;

[0060] like Figure 6 As shown, through J 1 / 2 The hole mobility (μh) obtained from the -V curve is 1.37×10 -8 cm 2 ·V -1 ·S -1 ; The migration rate of electrons is higher than the transfer rate of holes, and it is an electron transport material.

[0061] Example 5

[0062] In the present invention, based on the relevant photophysical properties of the light-emitting material in Case 1, an OLED device is provided, the OLED device includes an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode, the material of the organic thin film layer includes the above-mentioned organic compound; the material of the organic thin film layer can be one of the above-mentioned organic compounds, or can include a mixture of two or more of the above-mentioned organic compounds;

[0063] The preparation method of the OLED device device in the present invention comprises the following steps: cleaning 20 mm×20 mm ITO in ethanol and acetone solvents respectively, and placing the ITO in an inert atmosphere for drying and standby use; then spin coating a Pedot:PSS layer and a PVK layer on the ITO, and after completion, heating and annealing are respectively performed; spin coating the product (luminescent layer) solution, and annealing the luminescent layer to remove the solvent; vacuum depositing TBPi, Liq, and Al on the film respectively to prepare an OLED device; and finally obtaining an LED luminescent effective area of ​​2×2 mm 2 ; Its OLED device device is as follows Figure 4 As shown, ITO refers to the first electrode, PEDOT:PSS refers to the hole injection layer, PVK refers to the hole transport layer, ICZ

[10] CPP refers to the organic light-emitting functional layer, TBPi refers to the hole blocking layer, and Al refers to the second electrode;

[0064] In the present invention, the OLED device is as follows: a first electrode (ITO); a hole injection layer (PEDOT:PSS, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)), which is on the first electrode; a hole transport layer (PVK), which is on the hole injection layer; an organic light-emitting functional layer (ICZ

[10] CPP), which is on the hole transport layer; a hole blocking layer (TBPi, 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene), which is on the organic light-emitting functional layer; a second electrode, which is on the hole transport layer; the organic light-emitting functional layer includes a light-emitting layer; the light-emitting layer contains the organic photoelectric compound as described above;

[0065] like Figure 6 As shown, the device turn-on voltage of the OLED is 2.73V, the maximum external quantum efficiency can be maintained at 0.28%, and the tolerable voltage range is wide, which is between 4.50V and 7.50V.

[0066] Working principle:

[0067] In electronics:

[0068] Current is injected from the first electrode (ITO anode), and the holes injected from the anode attempt to transfer to the cathode; electrons are injected from the cathode; the electron transport layer (such as SnO2 and Liq) promotes the transfer of electrons, while the hole blocking layer (such as TBPi) prevents the holes from transferring to the cathode, so that the electrons and holes mainly meet and recombine in the organic light-emitting functional layer (such as ICZ

[10] CPP), thereby generating light emission.

[0069] In hole devices:

[0070] Similarly, current is injected from the first electrode (ITO anode); the hole injection layer (such as PEDOT) helps the holes to be injected smoothly, and the hole transport layer (such as PVK and MoO3) provides a transmission channel for the holes to be transmitted to the organic light-emitting functional layer; the electrons injected from the cathode are transmitted to the organic light-emitting functional layer; since the electron migration rate is higher than the hole migration rate, this device is more inclined to transmit holes; finally, the electrons and holes recombine in the organic light-emitting functional layer to realize luminescence.

[0071] In OLED devices:

[0072] The holes injected from the first electrode (ITO anode) are first efficiently injected through the hole injection layer (such as PEDOT:PSS), and then transported to the organic light-emitting functional layer through the hole transport layer (such as PVK); the electrons injected from the cathode also reach the organic light-emitting functional layer after being regulated by the hole blocking layer (such as TBPi); the electrons and holes effectively recombine in the organic light-emitting functional layer to generate light; the OLED device has a low turn-on voltage, and can maintain good performance within a wide voltage range of 4.50V to 7.50V, achieving a higher maximum external quantum efficiency.

[0073] By rationally designing each functional layer, effective injection, transmission and recombination of holes and electrons can be achieved, thereby achieving the purpose of luminescence, and by optimizing materials and structures, good photoelectric properties can be achieved.

[0074] The above-mentioned embodiments only express the implementation methods of the present invention, and cannot be understood as limiting the scope of the invention patent, nor is it any form of limitation on the structure of the present invention. It should be pointed out that for ordinary technicians in this field, several changes and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A novel nitrogen-containing cyclic compound, characterized in that: Including a structure having the following structural formula I: wherein R1 is independently selected from hydrogen, substituted or unsubstituted C1 to C 30 Alkyl, substituted or unsubstituted C1~C 30 heteroatom alkyl chains; R2 is independently selected from hydrogen, halogen, substituted or unsubstituted C1-C 30 Alkyl, substituted, unsubstituted C4~C 30 Arylalkyl, substituted, unsubstituted C6~C 30 The heteroaryl group is substituted with R2, and the 1st and 2nd positions of the benzene ring are symmetrically substituted; The structure of R2 is substituted, in addition to hydrogen, halogen and alkyl, and also has the following structure: The structure replacing the R2 may be a condensed ring conjugated with a benzene ring, i.e., a condensed ring of structural formula II, including a condensed ring substituted with a heteroatom; Wherein, R1 is independently selected from hydrogen, substituted, unsubstituted C1-C 30 Alkyl, substituted, unsubstituted C1~C 30 heteroatom alkyl chain, etc.; X1 and X2 are independently selected from substituted, unsubstituted heteroatoms and C atom aryl moieties.

2. A novel device of a nitrogen-containing cyclic compound, characterized in that: It comprises an electronic device, a hole device and an organic light emitting diode device; the electronic device, the hole device and the organic light emitting diode device all comprise the same first electrode and second electrode and a functional film layer; the functional film layer comprises a derivative of structural formula I.

3. The device of a novel nitrogen-containing cyclic compound according to claim 2, characterized in that: An organic material layer is included between the first electrode and the second electrode in the electronic device, and the organic material layer has the structural formula contained in the nitrogen-containing cyclic compound; the organic material layer in the electronic device includes an electron transport layer and a hole blocking layer, each with at least one layer.

4. The device of a novel nitrogen-containing cyclic compound according to claim 2, characterized in that: An organic material layer is included between the first electrode and the second electrode in the hole device. The organic material layer has a structural formula as contained in the nitrogen-containing cyclic compound. The organic material layer in the hole device includes at least one layer of a hole injection layer and a hole transport layer.

5. The device of a novel nitrogen-containing cyclic compound according to claim 2, characterized in that: An organic material layer is included between the first electrode and the second electrode in the organic light emitting diode device. The organic material layer has a structural formula as contained in the nitrogen-containing cyclic compound. The organic material layer in the organic light emitting diode device includes an electron transport layer and a hole blocking layer, each with at least one layer.

6. The device of a novel nitrogen-containing cyclic compound according to claim 3, characterized in that: The thickness of the electron transport layer and the hole blocking layer in the electronic device is 1nm to 600nm.

7. The device of a novel nitrogen-containing cyclic compound according to claim 4, characterized in that: The thickness of the hole injection layer and the hole transport layer in the hole device is 1nm to 600nm.

8. The device of a novel nitrogen-containing cyclic compound according to claim 5, characterized in that: The thickness of the electron transport layer and the hole blocking layer in the organic light emitting diode device is 1nm-600nm.

9. The device of a novel nitrogen-containing cyclic compound according to claim 2, characterized in that: The first electrode material is selected from one or more combinations of metals, metal oxides, conductive polymers, poly(9-vinylcarbazole), poly(3,4-ethylenedioxythiophene) and 4,4'-bis(N-carbazolyl)-biphenyl.

10. The device of a novel nitrogen-containing cyclic compound according to claim 2, characterized in that: The second electrode material may be a metal layer, a metal layer, a single layer containing one or more of metal oxides and metal halides, or a composite layer or a combination of a single layer and a composite layer.

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