Charge generation layer material and organic electroluminescent device

Abstract

The invention provides a charge generation layer material and an organic electroluminescent device, and the charge generation layer material has # imgabs0 #, and R is alkyl. According to the technical scheme, the problem of transverse crosstalk in the laminated device is solved by utilizing the directivity of material charge transmission.

Description

Technical Field

[0001] The present invention relates to the field of organic electroluminescent devices, in particular to a charge generation layer material and an organic electroluminescent device having the same. Background Art

[0002] Organic electroluminescence (EL), the emission of light from organic materials stimulated by electrical energy, was discovered over 50 years ago, but it wasn't until the advent of organic light-emitting diodes (OLEDs) in 1987 that this phenomenon gained widespread attention. Simply put, OLEDs utilize a multilayer organic thin-film structure to generate electroluminescent light. They are easy to manufacture and require only a very low drive voltage. Compared to LCDs, they possess superior display characteristics and quality, such as self-luminescence, wide viewing angles, high efficiency, a wide color gamut, and flexible display capabilities. Consequently, OLEDs have become the new generation of mainstream flat-panel displays.

[0003] OLED (organic light-emitting diode) is replacing LCD technology to become the main technology for high-performance display devices due to its own characteristics such as fast response speed, wide viewing angle, low power consumption, active light emission and adaptability to complex temperature environments. It has received more and more attention in the field of light emission and display.

[0004] With the development of OLED display technology, consumers have higher and higher requirements for the brightness and lifespan of displays. In order to solve this problem, many companies and researchers use internal connecting layers to connect two light-emitting layers in series to prepare stacked light-emitting devices in order to achieve better stability, higher luminous efficiency and longer lifespan.

[0005] The key technology in stacked device structures is the charge generation layer (CGL). To achieve low power consumption and low voltage, the CGL layer often uses materials with high charge mobility. However, this results in a high conductivity in the CGL layer, which can cause lateral crosstalk under the action of an electric field, making it difficult for AMOLED devices to meet customer optical requirements at low grayscale levels. Summary of the Invention

[0006] In view of the problems in the prior art, the object of the present invention is to provide a charge generation layer material with directionally selective charge transport and an organic electroluminescent device having the same.

[0007] According to one aspect of the present invention, a charge generation layer material is provided, comprising a compound having a structure shown in Formula I:

[0008]

[0009] Wherein, R is an alkyl group.

[0010] Preferably, R is an alkyl group with C≥8.

[0011] Preferably: the R is C 15 H 31 .

[0012] According to another aspect of the present invention, an organic electroluminescent device is provided, comprising the above-mentioned charge generation layer material.

[0013] Preferably, the method comprises a first light-emitting functional layer, a second light-emitting functional layer and a charge generation layer located between the first light-emitting functional layer and the second light-emitting functional layer, wherein the first light-emitting functional layer and the second light-emitting functional layer are connected via the charge generation layer.

[0014] Preferably, the charge generation layer contains the charge generation layer material.

[0015] Preferably, the first light-emitting functional layer includes a first hole injection / transport layer, a first electron blocking layer, a first light-emitting layer, and a first electron injection / transport layer stacked in sequence.

[0016] Preferably, the second light-emitting functional layer includes a second hole injection / transport layer, a second electron blocking layer, a second light-emitting layer, and a second electron injection / transport layer stacked in sequence.

[0017] Preferably, the charge generation layer is located between the first electron injection / transport layer and the second hole injection / transport layer.

[0018] Preferably, an anode is provided below the first hole injection / transport layer, and a cathode is provided above the second electron injection / transport layer.

[0019] The charge generation layer material and the organic electroluminescent device having the same of the present invention select a new n-CGL layer material with directionally selective charge transport and utilize the directionality of the material's charge transport to solve the lateral crosstalk problem in the stacked device. DETAILED DESCRIPTION

[0020] The exemplary embodiments will now be described more fully with reference to examples. However, the exemplary embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be comprehensive and complete and will fully convey the concepts of the exemplary embodiments to those skilled in the art.

[0021] In an embodiment of the present invention, a charge generation layer material and an organic electroluminescent device having the same are provided.

[0022] A compound having the structure shown in Formula I:

[0023]

[0024] Wherein, R is an alkyl group.

[0025] The side chain substituent R is a solubilizing group, preferably R is an alkyl group with a carbon number of ≥8. 15 H 31 .

[0026] The organic electroluminescent device includes the following layers stacked in sequence from bottom to top: an anode, a first hole injection / transport layer, a first electron blocking layer, a first light-emitting layer, a first electron injection / transport layer, a charge generation layer, a second hole injection / transport layer, a second electron blocking layer, a second light-emitting layer, a second electron injection / transport layer, a cathode, and an optical extraction layer.

[0027] Preferably, an n-charge generation layer is plated on the electron injection / transport layer by inkjet printing through a mask, and the thickness is preferably 50-200 nm.

[0028] To reduce lateral crosstalk in stacked devices and improve optical quality at low grayscale levels, the present invention provides a novel charge generation layer material. Due to strong intermolecular π-π interactions and H-aggregation, the charge transfer rate of the compound is higher in the direction where the conjugated planes overlap, while it is lower in other directions (by five orders of magnitude). Through molecular self-assembly, the molecular arrangement of the charge generation layer can be manipulated, resulting in a higher lateral resistance and lower longitudinal resistance, thus resolving the crosstalk problem that occurs when stacked light-emitting devices are subjected to low voltages.

[0029] The following specific embodiments describe the present invention:

[0030] The preparation method of formula I is as follows:

[0031] Step 1:

[0032] Weigh 1 mol of compound 1 into a flask, add 1.1 mol of alkylamine liquid under N protection, and stir at room temperature for 4 hours with dichloromethane as the solvent to obtain a crude product. After extraction with deionized water, the product is purified by column chromatography using dichloromethane:petroleum ether = 1:5 as the eluent to obtain a light yellow product, compound 2.

[0033]

[0034] Step 2:

[0035] Weigh 1 mmol of compound 3 into a reaction flask, add 3 mmol of compound 2, 1 mL of triethylamine, and 5 mL of quinoline solution, and heat with stirring at 180°C under N2 protection for 10 hours or overnight. After cooling, add HCl to quench the reaction, extract, and wash with water to obtain a crude product. Purify the product using column chromatography using toluene:ethyl acetate:petroleum ether = 10:2:1 as the eluent to obtain a white powder of Formula I.

[0036] The structure of the compound was confirmed by hydrogen nuclear magnetic resonance spectroscopy.

[0037]

[0038] In addition, two isomers, cis and trans, are generated in the second step, i.e., another isomer of the structure shown in Formula I:

[0039]

[0040] However, due to their similar polarity, the separation of isomers is more difficult and has little impact on the device. In current research, except for specific academic research directions such as research on methodology and isomers, no distinction is generally made and they are treated as one compound.

[0041] Example 1

[0042] Let R be C 15 H 31 , to prepare the compound of Example 1:

[0043]

[0044] The structure of the compound was confirmed by hydrogen nuclear magnetic resonance spectroscopy: 1H NMR (C6D5Cl, 398K, 500MHz): δ (ppm). 9.17 (br, 1H), 8.96 (br, 2H), 8.40 (m, 15H), 5.54 (m, 3H), 2.70 (m, 6H), 2.45 (m, 6H), 1.80 (m, 24H), 1.68 (m, 12H), 1.64 (24H), 1.18 (m, 18H)

[0045] Performance test of the compound of the embodiment: The compound of Example 1 was dissolved in an acetone-isopropanol solution, and a thin film was prepared by the drop film method and annealed at 130° C. The electron mobility was tested using the space-confined current (SCLC) model.

[0046] The charge mobility (cm 2 V -1 S -1 ), horizontal: 2.98×10 -9 , vertical: 1.43×10 -4 .The thermal decomposition temperature is 402℃.

[0047] In summary, the charge generation layer material of the present invention utilizes the directionality of charge transfer to increase lateral resistance and reduce lateral crosstalk. The organic electroluminescent device having the charge generation layer material solves the lateral crosstalk problem in the stack.

[0048] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A charge generation layer material, characterized in that: A compound having the structure shown in Formula I: Wherein, R is an alkyl group.

2. The charge generation layer material according to claim 1, wherein: The R is an alkyl group with C≥8.

3. The charge generation layer material according to claim 2, wherein: The R is C 15 H 31 .

4. An organic electroluminescent device, characterized in that: Contains the charge generating layer material according to any one of claims 1 to 3.

5. The organic electroluminescent device according to claim 4, wherein: The invention comprises a first light-emitting functional layer, a second light-emitting functional layer and a charge generation layer located between the first light-emitting functional layer and the second light-emitting functional layer, wherein the first light-emitting functional layer and the second light-emitting functional layer are connected via the charge generation layer.

6. The organic electroluminescent device according to claim 5, wherein: The charge generation layer contains the charge generation layer material.

7. The organic electroluminescent device according to claim 5, wherein: The first light-emitting functional layer includes a first hole injection / transport layer, a first electron blocking layer, a first light-emitting layer, and a first electron injection / transport layer stacked in sequence.

8. The organic electroluminescent device according to claim 7, wherein: The second light-emitting functional layer includes a second hole injection / transport layer, a second electron blocking layer, a second light-emitting layer, and a second electron injection / transport layer stacked in sequence.

9. The organic electroluminescent device according to claim 8, wherein: The charge generation layer is located between the first electron injection / transport layer and the second hole injection / transport layer.

10. The organic electroluminescent device according to claim 8, wherein: An anode is provided under the first hole injection / transport layer, and a cathode is provided on the second electron injection / transport layer.

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