An electron transport layer material with phenanthreneimidazole as the core framework, an organic light-emitting diode, and a preparation method thereof.

Abstract

This invention relates to the field of organic electroluminescent display technology, specifically to an electron transport layer material with phenanthreneimidazole as the core framework, an organic electroluminescent diode, and a fabrication method. The ETM, obtained by introducing simple substituents at the N1 and C2 positions, is simple to synthesize and has a high yield. This type of ETM successfully balances the contradiction between conjugation degree and triplet energy level (ET), achieving wide bandgap, high ET, and high electron mobility. OLED devices fabricated with this type of ETM can achieve low turn-on voltage and high device efficiency. For example, CH3OPICN achieves a turn-on voltage of 4 × 10⁻⁶. 5 V cm ‑1 Under an electric field strength of [insert value here], the electron mobility can reach 4.4 × 10 [insert value here]. ‑5 cm 2 V ‑1 s ‑1 Blue OLED devices fabricated using this as an electron transport layer exhibit a turn-on voltage of 3.0V and a density of 83180 cd·m². ‑2 Its brightness reaches 15.7 cd·A. ‑1 The current efficiency is 11.8 lm·W. ‑1 With a power efficiency of 7.7% and an external quantum efficiency, it is an excellent ETM that can be commercialized.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescent display technology, specifically to the design of an electron transport layer material with phenanthreneimidazole as the core framework and a method for fabricating organic electroluminescent diodes. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have made remarkable progress since 1987 and are considered a very promising next-generation display and lighting technology. Currently, the most widely used OLED device structure is a three-layer structure, including a cathode, an anode, a hole transport layer, a light-emitting layer, and an electron transport layer. The transport layer promotes the balance of charge carrier transport, thereby enabling the device to achieve higher luminous efficiency and stronger stability. However, due to the inherent properties of organic materials, the hole transport capability is often much greater than the electron transport capability. Among the reported transport layer materials, hole transport materials (HTMs) have a mobility that is even two orders of magnitude higher than that of electron transport materials (ETMs). Many excellent ETMs have been reported, but developing electron transport materials with superior overall performance remains a challenge.

[0003] Introducing electron-deficient or strongly electron-withdrawing groups with nitrogen atoms into the π-conjugated framework is beneficial for obtaining excellent ETMs with high mobility and high thermal stability. However, highly conjugated molecules often have lower triplet energy levels (E0). T This can lead to the excitons formed in the luminescent layer being quenched by transferring to the electron transport layer, resulting in unsatisfactory effects even with high mobility. Therefore, a trade-off exists between the degree of molecular conjugation and the triplet energy level when designing an ETM.

[0004] This invention designs an excellent electron transport material with high mobility, high thermal stability, and high triplet energy level by selecting a reasonable conjugated framework and electron-deficient groups. The material has a simple structure and can become a low-cost ETM that can replace the commercial electron transport material TPBi. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an excellent electron transport material with low cost, high mobility, high thermal stability, and high triplet energy level, which is expected to replace the commercial electron transport material TPBi, and an organic electroluminescent diode.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An electron transport layer material with phenanthreneimidazole as the core framework.

[0008] The electron transport material on the electron transport layer is PPI, and its structural formula is Equation 1:

[0009]

[0010]

[0011] In Equation 1,

[0012] Both R1 and R2 are One of -OCH3, -CN, or -CONH2, where R1 and R2 are different.

[0013] Furthermore,

[0014] The specific structures of Formula 1 are as follows: 12 types:

[0015]

[0016]

[0017] Furthermore, the principle behind the high electron mobility of the electron transport layer is as follows:

[0018] Hydrogen bond cages, acting as network nodes, play a crucial role in the formation of three-dimensional hydrogen bond networks. The formation of three-dimensional hydrogen bond networks is determined by the hydrogen bond network nodes. Hydrogen bond cages formed by CH···N, acting as network nodes, play a crucial role in the formation of three-dimensional hydrogen bond networks. With the assistance of CH···π network links, a novel three-dimensional hydrogen bond network structure is generated, ultimately achieving high mobility.

[0019] An organic light-emitting diode (OLED) includes the aforementioned electron transport layer, and further comprises a transparent substrate, an ITO anode, a hole injection layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron injection layer, and a cathode.

[0020] Furthermore, the hole injection layer is HATCN; the hole transport layer is TAPC; the electron blocking layer is TCTA; the electron injection layer is LiF; and the cathode is Al.

[0021] Furthermore, the molecular formulas of HATCN, TAPC, and TCTA are as follows:

[0022]

[0023]

[0024] Furthermore, the organic light-emitting layer is a fluorescent or phosphorescent material;

[0025] Alternatively, the organic light-emitting layer may be one of the following: blue fluorescent material MADN:DSA-PH (2%), red phosphorescent material BePP2:Ir(MDQ)2(acac) (15%), and green phosphorescent material BePP2:Ir(ppy)2(acac) (15%).

[0026] Furthermore, the molecular formulas of MADN, BePP2, DSA-PH, Ir(MDQ)2(acac), and Ir(ppy)2(acac) are as follows:

[0027]

[0028] A method for fabricating the above-mentioned organic light-emitting diode includes the following steps:

[0029] 1) Clean the ITO substrate;

[0030] 2) After cleaning, the ITO substrate undergoes surface oxygen treatment and is then transferred to a vacuum evaporation chamber;

[0031] 3) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the hole injection layer HATCN in the vacuum chamber;

[0032] 4) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the hole transport layer TAPC in the vacuum chamber;

[0033] 5) Adjust the temperature of the vapor deposition thermocouple and vapor deposit a hole-blocking layer TCTA in the vacuum chamber;

[0034] 6) Adjust the temperature of the vapor deposition thermocouple, and vapor deposit the light-emitting layer MADN:DSA-PH(2%) / BePP2:Ir(MDQ)2(acac)(15%) / BePP2:Ir(ppy)2(acac)(15%) in the vacuum chamber, and adjust the evaporation rate ratio of the host and guest in the vacuum chamber to the corresponding doping concentration ratio;

[0035] 7) Adjust the temperature of the vapor deposition thermocouple and vapor deposit CH3OPICN in the vacuum chamber;

[0036] 8) Adjust the power of the vapor deposition thermocouple to vapor deposit the electron injection layer of LiF;

[0037] 9) Adjust the power of the aluminum vapor deposition pot to vapor deposit the cathode layer of Al.

[0038] Furthermore,

[0039] In step 1), the ITO substrate is rubbed with ITO cleaning solution. After rubbing, it is ultrasonicated with acetone solvent, ITO cleaning solution and deionized water for more than 35 minutes in sequence. The moisture is then dried with an air gun and placed in a 120℃ oven for drying.

[0040] In step 3), the evaporation rate is 0.05 nm / s and the thickness of the vapor-deposited film is 20 nm.

[0041] In step 4), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 40 nm.

[0042] In step 5), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 10 nm.

[0043] In step 6), the total evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 20 nm.

[0044] In step 7), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 40 nm.

[0045] In step 8), the evaporation rate is adjusted to 0.01 nm / s and monitored using a frequency meter, and the thickness of the vapor-deposited film is 1 nm.

[0046] In step 9), the evaporation rate is adjusted to 0.1 nm / s, and 2 nm is evaporated without the baffle to remove Al2O3. Then the baffle is opened and the power is gradually increased to adjust the evaporation rate to 0.3-0.5 nm / s, and the film thickness is 100 nm.

[0047] The beneficial effects of this invention, which discloses an electron transport layer material with phenanthreneimidazole as its core framework, an organic electroluminescent diode, and a preparation method, are as follows: PPI-based materials possess effective electron injection, hole / exciton blocking properties, and excellent thermal stability, making them highly suitable as framework materials for ETMs. This invention bonds simple groups, such as electron-deficient pyridinium groups, electron-withdrawing methoxy and cyano groups, or weakly electron-donating amide groups, to the N1 and C2 active sites of the phenanthreneimidazole (PPI) group, resulting in a series of materials with electron transport properties that can be used as electron transport layers in OLED devices. These materials differ from commercially available electron transport materials, such as TPBi, in that they offer significant advantages such as simple synthesis and high yield, with most molecules achieving yields of around 80%. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of an OLED device according to an embodiment of the present invention;

[0049] Figure 2 The images show the UV absorption and fluorescence emission of CH3OPICN tetrahydrofuran in solution and thin film states in this invention.

[0050] Figure 3 The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) plots of CH3OPICN in this embodiment of the invention are shown below.

[0051] Figure 4This is a cyclic voltammetry curve of CH3OPICN according to an embodiment of the present invention;

[0052] Figure 5 This is a current density-voltage-brightness curve of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0053] Figure 6 This is an external quantum efficiency-brightness curve of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0054] Figure 7 This is a spectrum of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0055] Figure 8 This is a current efficiency-brightness-power efficiency curve of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0056] Figure 9 This is a brightness-current density curve of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0057] Figure 10 This is a device lifetime (LT50)-driving voltage curve of a blue fluorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0058] Figure 11 This is a current density-voltage-brightness curve of a red phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0059] Figure 12 This is an external quantum efficiency-brightness curve of a red phosphorescent OLED device with CH3OPICN and ETM in an embodiment of the present invention.

[0060] Figure 13 This is a spectrum of a red phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0061] Figure 14 This is a current efficiency-brightness-power efficiency curve of a red phosphorescent OLED device with CH3OPICN and ETM as an embodiment of the present invention.

[0062] Figure 15 This is a brightness-current density curve of a red phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0063] Figure 16This is a device lifetime (LT50)-driving voltage curve of a red phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0064] Figure 17 This is a current density-voltage-brightness curve of a green phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0065] Figure 18 This is an external quantum efficiency-brightness curve of a green phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention;

[0066] Figure 19 The image shows the spectrum of a green phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0067] Figure 20 This is a current efficiency-brightness-power efficiency curve of a green phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0068] Figure 21 This is a brightness-current density curve of a green phosphorescent OLED device with CH3OPICN as ETM according to an embodiment of the present invention.

[0069] Figure 22 This is a device lifetime (LT50) - driving voltage curve of the green phosphorescent OLED device with CH3OPICN as ETM in an embodiment of the present invention;

[0070] Figure 23 This is an electric field intensity-mobility diagram of CH3OPICN according to an embodiment of the present invention;

[0071] Figure 24 This is a schematic diagram illustrating the principle of high electron mobility using CH3OPICN as an electron transport layer in an embodiment of the present invention.

[0072] Figure 25 This is a comparison of experimental results for green OLEDs using CH3OPICN and TPBi as electron transport layers in embodiments of the present invention.

[0073] Figure 26 This is a comparison of experimental results for red OLEDs using CH3OPICN and TPBi as electron transport layers, respectively, in embodiments of the present invention.

[0074] Figure 27 The mobility results of CH3OPICN, CH3OPICONH2 and TPBi as electron transport layers in this embodiment of the invention are compared. Detailed Implementation

[0075] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0076] Example 1:

[0077] An electron transport layer material with phenanthreneimidazole as the core framework.

[0078] The electron transport material on the electron transport layer is 4-(1-(4-methoxyphenyl)-1H-o-diazaphenanthroline[9,10-d]imidazolium-2-yl)benzyl nitrile (CH3OPICN);

[0079] Synthetic route of CH3OPICN:

[0080]

[0081] As shown in the synthetic route above, a mixture of 9,10-phenanthrene (2.00 g, 9.61 mmol), 4-methoxyaniline (4.73 g, 38.4 mmol), 4-cyanobenzaldehyde (1.26 g, 9.61 mmol), and ammonium acetate (3.70 g, 48.03 mmol) was added to a solution of acetic acid (30 mL). The mixture was refluxed at 120 °C for 2 hours under nitrogen atmosphere to obtain the final product CH3OPICN in a single step. After cooling, the solid product was filtered and washed with water (30 mL) / acetic acid (30 mL) at a ratio of 1:1, then dissolved in CH2Cl2 and dried in MgSO4, and concentrated under vacuum. Column chromatography was performed using dichloromethane / petroleum ether (3:1; v:v) as eluent, yielding a white solid. The crude product was purified by recrystallization from ethanol to obtain a white solid in a yield of 76% (3.11 g).

[0082] NMR and mass spectrometry data of the final product CH3OPICN: ¹H NMR (500MHz, Chloroform-d) δ 8.83 (dd, J = 8.0, 1.5Hz, 1H), 8.77 (d, J = 8.3Hz, 1H), 8.70 (d, J = 8.3Hz, 1H), 7.82–7.70 (m, 3H), 7.67 (ddd, J = 8.4, 6.9, 1.5Hz, 1H), 7.61–7.50 (m, 3H), 7.47–7.38 (m, 2H), 7.31 (ddd, J = 8.2, 6.9, 1.2Hz, 1H), 7.26–7.23 (m, 0H), 7.16–7.07 (m, 2H). ¹³C NMR (126MHz, CDCl3) δ158.71,146.62,135.64,132.94,129.99,128.74,127.91,127.66,127.49,127.00,126.47,125.49,125.06,124 .52,124.00,123.43,122.21,121.22,120.94,120.67,119.00,116.61,113.60,110.03,75.31,75.06,74.80,53.74.HRMS(ESI+):m / z calcd for C29H19N3O+H+:426.49100; found:426.15988.

[0083] like Figure 24 As shown, the principle behind the high electron mobility of the electron transport layer is:

[0084] Hydrogen bond cages, acting as network nodes, play a crucial role in the formation of three-dimensional hydrogen bond networks. The formation of three-dimensional hydrogen bond networks is determined by the hydrogen bond network nodes. Hydrogen bond cages formed by CH···N, acting as network nodes, play a crucial role in the formation of three-dimensional hydrogen bond networks. With the assistance of CH···π network links, a novel three-dimensional hydrogen bond network structure is generated, ultimately achieving high mobility.

[0085] According to the appendix Figures 2-4 It can be seen that the fluorescence emission peaks of CH3OPICN in tetrahydrofuran (THF) solution and thin film are 477 nm and 458 nm, respectively, which are blue light emission; no significant T emission was observed within the monitoring range. g T d It has a temperature of 317℃ and good thermal stability; CH3OPICN has a wide band gap, with the HOMO level at 5.51eV and the LUMO level at 2.56eV; the triplet level has a relatively high energy level of 2.35eV.

[0086] From the appendix Figure 23It can be seen that the compound 4-(1-(4-methoxyphenyl)-1H-o-diazaphenanthrene[9,10-d]imidazolium-2-yl)benzyl nitrile (CH3OPICN) has a 4×10 5 V cm -1 Under an electric field strength of [insert value here], the electron mobility can reach 4.4 × 10 [insert value here]. -5 cm 2 V -1 S -1 It is an organic material with high mobility.

[0087] Example 2:

[0088] An organic light-emitting diode, such as Figure 1 As shown, it is composed of a transparent substrate, an ITO anode, a hole injection layer (HATCN), a hole transport layer (TAPC), an electron blocking layer (TCTA), an organic light-emitting layer, an electron transport layer (ETM), an electron injection layer (LiF), and a cathode (Al). The electron transport layer is the structure in Example 1. The organic light-emitting layer is a blue phosphor MADN:DSA-PH (2%), a red phosphorescent material BePP2:Ir(MDQ)2(acac) (15%), or a green phosphorescent material BePP2:Ir(ppy)2(acac) (15%).

[0089] The molecular formulas of HATCN, TAPC, and TCTA are:

[0090]

[0091]

[0092] The molecular formulas of MADN, BePP2, DSA-PH, Ir(MDQ)2(acac), and Ir(ppy)2(acac) are:

[0093]

[0094]

[0095] A method for fabricating the above-mentioned organic light-emitting diode includes the following steps:

[0096] 1) Cleaning ITO substrate: Scrub the ITO substrate with ITO cleaning solution. After scrubbing, use acetone solvent, ITO cleaning solution and deionized water in sequence and sonicate for more than 35 minutes. Blow dry the water with an air gun and put it in a 120℃ oven to dry for later use.

[0097] 2) Perform surface oxygen treatment on the cleaned and dried ITO substrate and transfer it to the vacuum evaporation chamber;

[0098] 3) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the hole injection layer HATCN in the vacuum chamber at a rate of 0.05 nm / s and a film thickness of 20 nm.

[0099] 4) Adjust the temperature of the evaporation thermocouple and evaporate the hole transport layer TAPC in the vacuum chamber. The evaporation rate is adjusted to 0.1 nm / s and the evaporation film thickness is 40 nm.

[0100] 5) Adjust the temperature of the vapor deposition thermocouple and vapor deposit a hole-blocking layer TCTA in the vacuum chamber. The evaporation rate is adjusted to 0.1 nm / s and the vapor deposition film thickness is 10 nm.

[0101] 6) Adjust the temperature of the vapor deposition thermocouple, and vapor deposit the light-emitting layer MADN:DSA-PH(2%) / BePP2:Ir(MDQ)2(acac)(15%) / BePP2:Ir(ppy)2(acac)(15%) in the vacuum chamber. Adjust the evaporation rate ratio of the host and guest in the vacuum chamber to the corresponding doping concentration ratio, adjust the total evaporation rate to 0.1nm / s, and the vapor deposition film thickness to 20nm.

[0102] 7) Adjust the temperature of the vapor deposition thermocouple, vapor deposit CH3OPICN in the vacuum chamber, adjust the evaporation rate to 0.1 nm / s, and the vapor deposition film thickness to 40 nm;

[0103] 8) Adjust the power of the vapor deposition thermocouple, use a frequency meter to adjust the evaporation rate of LiF in the vacuum chamber to 0.01 nm / s, and use a frequency meter to monitor the vapor deposition of a hole transport layer film with a thickness of 1 nm.

[0104] 9) Adjust the power of the aluminum vapor deposition pot to set the evaporation rate of Al to 0.1 nm / s. First, remove Al2O3 by evaporating 2 nm without opening the baffle. Then, open the baffle and gradually increase the power to adjust the evaporation rate to 0.3-0.5 nm / s. The vapor deposition film thickness is 100 nm.

[0105] The structures of blue fluorescent / red phosphorescent / green phosphorescent OLED devices using CH3OPICN as ETM are as follows:

[0106] ①HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / MADN:DSA-PH(2%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm).

[0107] ②HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(MDQ)2(acac)(15%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm)

[0108] ③HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(ppy)2(acac)(15%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm)

[0109] Depend on Figures 5-11 It is known that the blue fluorescent OLED device prepared by ETM using compound 4-(1-(4-methoxyphenyl)-1H-o-diazaphenanthroline[9,10-d]imidazolium-2-yl)benzyl nitrile (CH3OPICN) has an on-state voltage of 3.0V and a luminance of 83180 cd·m. -2 The current efficiency is as high as 15.7 cd·A. -1 The power efficiency is 11.8 lm·W. -1 The external quantum efficiency reaches 7.7%.

[0110] Depend on Figure 12 As shown in Appendix 18, compound 4-(1-(4-methoxyphenyl)-1H-o-diazaphenanthroline[9,10-d]imidazolium-2-yl)benzyl nitrile (CH3OPICN) has an ETM-based red phosphorescent OLED device with a turn-on voltage of 3.0V and a luminance of 58456 cd·m. -2 The current efficiency is as high as 19.6 cd·A. -1 The power efficiency is 17.1 lm·W. -1 The external quantum efficiency reaches 15.9%.

[0111] Depend on Figures 19-23 It is known that the green phosphorescent OLED device prepared by ETM using compound 4-(1-(4-methoxyphenyl)-1H-o-diazaphenanthroline[9,10-d]imidazolium-2-yl)benzyl nitrile (CH3OPICN) has an on-state voltage of 2.6V and a brightness of 83180 cd·m. -2 The current efficiency is as high as 83.6 cd·A. -1 The power efficiency is 89.6 lm·W. -1 The external quantum efficiency reaches 21.9%.

[0112] The results of all three devices are better than those of the device that replaces ETM with TPBi.

[0113] CH3OPICN is an organic material with a simple synthesis method, excellent thermal stability, high mobility, wide band gap, and suitable triplet energy. When used as an ETM to fabricate OLED devices, it has achieved higher device efficiency than the commercially available ETM, TPBi.

[0114] Example 3:

[0115] The classic blue fluorescent molecule DSA-PH was doped into the host material MADN as the emitting layer: the mass of DSA-PH accounted for 2% of MADN (MADN:DSA-PH (2%)). The two molecules CH3OPICN and CH3OPICONH2 mentioned above were compared with the classic TPBi as the electron transport layer, as follows:

[0116] 1. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / MADN:DSA-PH(2%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm)

[0117] 2. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / MADN:DSA-PH(2%)(20nm) / CH3OPICONH2(40nm) / LiF(1nm) / Al(100nm)

[0118] 3. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / MADN:DSA-PH(2%)(20nm) / TPBi(40nm) / LiF(1nm) / Al(100nm)

[0119] The comparison results are shown below. Figure 27 Tables 1 and 2:

[0120] Table 1 Results of blue OLEDs using CH3OPICN, CH3OPICONH2, and TPBi as electron transport layers

[0121]

[0122] Note: (a)V turn-on Brightness is 1 cd m -2 (a) the turn-on voltage; (b) LE max (c) PE max (d) EQE: Maximum power efficiency; (e) L max Maximum brightness; (f)λ EL,max : Maximum electroluminescence peak position; (g)V end : End voltage; (h)CIE: Color coordinates.

[0123] Table 2 Results of blue OLEDs using CH3OPICN, CH3OPICONH2, and TPBi as electron transport layers

[0124]

[0125] The results show that when CH3OPICN is used as the electron transport layer, the maximum external quantum efficiency is 7.7%, which is better than the performance of devices using TPBi as the electron transport layer.

[0126] Example 4:

[0127] Green fluorescent molecule Ir(ppy)2(acac) was doped into the host material BePP2 as the emitting layer: Ir(ppy)2(acac) accounted for 15% of BePP2 (BePP2:Ir(ppy)2(acac)(15%)). A comparison was made between CH3OPICN as the electron transport layer and the classic TPBi as the electron transport layer, as follows:

[0128] 1. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(ppy)2(acac)(15%)(20nm) / TPBi(40nm) / LiF(1nm) / Al(100nm)

[0129] 2. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(ppy)2(acac)(15%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm)

[0130] The comparison results are shown below. Figure 25 Tables 3 and 4:

[0131] Table 3 Comparison of experimental results of green OLEDs using CH3OPICN and TPBi as electron transport layers 1

[0132]

[0133] Table 4 Comparison of experimental results for green OLEDs using CH3OPICN and TPBi as electron transport layers.

[0134]

[0135] Note: (a)EQE max (a) Maximum external quantum efficiency; (b) EQE @100 Brightness is 100 cd / m -2 The EQE value at that time; (c) EQE @1000 Brightness is 1000 cd / m -2 The EQE value at that time.

[0136] Example 5:

[0137] The red fluorescent molecule Ir(MDQ)2(acac) was doped into the host material BePP2 as the emitting layer: the mass of Ir(MDQ)2(acac) accounted for 15% of BePP2 (BePP2:Ir(MDQ)2(acac)(15%)). A comparison was made between CH3OPICN as the electron transport layer and the classic TPBi as the electron transport layer, as follows:

[0138] 1. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(MDQ)2(acac)(15%)(20nm) / TPBi(40nm) / LiF(1nm) / Al(100nm)

[0139] 2. HATCN(20nm) / TAPC(40nm) / TCTA(5nm) / BePP2:Ir(MDQ)2(acac)(15%)(20nm) / CH3OPICN(40nm) / LiF(1nm) / Al(100nm)

[0140] The comparison results are shown below. Figure 26 Tables 5 and 6:

[0141] Table 5 Comparison of experimental results for red OLEDs using CH3OPICN and TPBi as electron transport layers.

[0142]

[0143] Table 6. Comparison of experimental results for red OLEDs using CH3OPICN and TPBi as electron transport layers.

[0144]

[0145] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An electron transport layer material with phenanthreneimidazole as the core framework, characterized in that: The specific structure of the electron transport layer is as follows: Hydrogen bond cages, acting as network nodes, play a crucial role in the formation of a three-dimensional hydrogen bond network. The formation of the three-dimensional hydrogen bond network is determined by the hydrogen bond network nodes. Hydrogen bond cages formed by CH···N, acting as network nodes, play a crucial role in the formation of a three-dimensional hydrogen bond network. With the assistance of the CH···π network, a novel three-dimensional hydrogen bond network structure is generated, ultimately achieving high mobility.

2. An organic light-emitting diode, characterized in that: The device includes the electron transport layer as described in claim 1, and further comprises a transparent substrate, an ITO anode, a hole injection layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron injection layer, and a cathode.

3. The organic light-emitting diode according to claim 2, characterized in that: The hole injection layer is HATCN; the hole transport layer is TAPC; the electron blocking layer is TCTA; the electron injection layer is LiF; and the cathode is Al.

4. The organic light-emitting diode according to claim 3, characterized in that: The molecular formulas of HATCN, TAPC, and TCTA are: 。 5. The organic light-emitting diode according to claim 2, characterized in that: The organic light-emitting layer is a fluorescent or phosphorescent material; The organic light-emitting layer is one of the following: blue fluorescent material MADN:DSA-PH, red phosphorescent material BePP2:Ir(MDQ)2(acac), and green phosphorescent material BePP2:Ir(ppy)2(acac); In the blue fluorescent material MADN:DSA-PH, the content of DSA-PH is 2%; in the red phosphorescent material BePP2:Ir(MDQ)2(acac), the content of Ir(MDQ)2(acac) is 15%; and in the green phosphorescent material BePP2:Ir(ppy)2(acac), the content of Ir(ppy)2(acac) is 15%.

6. The organic light-emitting diode according to claim 5, characterized in that: The molecular formulas of MADN, BePP2, DSA-PH, Ir(MDQ)2(acac), and Ir(ppy)2(acac) are: 。 7. A method for preparing an organic light-emitting diode according to any one of claims 2-6, characterized in that: Includes the following steps, 1) Clean the ITO substrate; 2) After cleaning, the ITO substrate undergoes surface oxygen treatment and is then transferred to a vacuum evaporation chamber; 3) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the hole injection layer HATCN in the vacuum chamber; 4) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the hole transport layer TAPC in the vacuum chamber; 5) Adjust the temperature of the vapor deposition thermocouple and vapor deposit a hole-blocking layer TCTA in the vacuum chamber; 6) Adjust the temperature of the vapor deposition thermocouple and vapor deposit the light-emitting layer MADN:DSA-PH / BePP2:Ir(MDQ)2(acac) / BePP2:Ir(ppy)2(acac) in the vacuum chamber. The content of DSA-PH in MADN:DSA-PH is 2%, the content of Ir(MDQ)2(acac) in BePP2:Ir(MDQ)2(acac) is 15%, and the content of Ir(ppy)2(acac) in BePP2:Ir(ppy)2(acac) is 15%. Adjust the evaporation rate ratio of the host and guest in the vacuum chamber to the corresponding doping concentration ratio. 7) Adjust the temperature of the vapor deposition thermocouple and vapor deposit CH3OPICN in the vacuum chamber; 8) Adjust the power of the vapor deposition thermocouple to vapor deposit the electron injection layer of LiF; 9) Adjust the power of the aluminum vapor deposition pot to vapor deposit the cathode layer of Al.

8. The method for preparing an organic light-emitting diode according to claim 7, characterized in that: In step 1), the ITO substrate is rubbed with ITO cleaning solution. After rubbing, it is ultrasonicated with acetone solvent, ITO cleaning solution and deionized water for more than 35 minutes in sequence. The moisture is then dried with an air gun and placed in a 120℃ oven for drying. In step 3), the evaporation rate is 0.05 nm / s and the thickness of the vapor-deposited film is 20 nm. In step 4), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 40 nm. In step 5), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 10 nm. In step 6), the total evaporation rate is adjusted to 0.1 nm / s, and the evaporation film thickness is 20 nm. In step 7), the evaporation rate is adjusted to 0.1 nm / s, and the thickness of the vapor-deposited film is 40 nm. In step 8), the evaporation rate is adjusted to 0.01 nm / s and monitored using a frequency meter, and the thickness of the vapor-deposited film is 1 nm. In step 9), the evaporation rate is adjusted to 0.1 nm / s, and 2 nm of Al2O3 is removed without opening the baffle. Then the baffle is opened and the power is gradually increased to adjust the evaporation rate to 0.3~0.5 nm / s, and the film thickness is 100 nm.

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