Organic electroluminescent device and display device

Abstract

The present invention provides an organic electroluminescent device and a display device. The organic electroluminescent device comprises a functional luminescent layer, and the luminescent layer has a current of no more than 0.01 mA / cm 2 In the first target current density interval, the electron mobility V E and hole mobility V H The requirements of Formula 1 are met. The organic electroluminescent device has a lower luminous efficiency at a low gray scale, thereby showing a relatively excellent display quality.

Description

Technical Field

[0001] The invention relates to an organic electroluminescent device and a display device, belonging to the technical field of organic electroluminescent. Background Art

[0002] Organic electroluminescent devices include a cathode, an anode, and a light-emitting layer located between the cathode and the anode. By applying voltage between the cathode and the anode, electrons from the cathode and holes from the anode will recombine in the light-emitting layer to generate excitons, which will emit light accompanied by the radiative relaxation of the excitons to the ground state.

[0003] At present, the light color of organic electroluminescent devices is determined by the three luminescent materials of red, green and blue in the luminescent layer, and different light colors are achieved by adjusting the different luminescent ratios of the three luminescent materials. Based on the demand for luminous efficiency and service life of organic electroluminescent devices, at present, red and green luminescent materials mostly use high-efficiency phosphorescent luminescent materials, while blue light uses long-life fluorescent luminescent materials.

[0004] However, this material combination often makes the red and green lights still have high luminous efficiency at low grayscale, which makes it difficult to control the luminous ratio of red and green lights, such as the difficulty in turning off the red and green lights, and the red and green lights causing crosstalk to the blue light, which ultimately leads to serious display problems at low grayscale. Having excellent display quality at low grayscale is one of the core standards for evaluating the performance of organic electroluminescent devices. Therefore, how to make organic electroluminescent devices have excellent display quality at low grayscale is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present invention provides an organic electroluminescent device, which can significantly suppress the problems of light crosstalk and the like at low gray scales, thereby showing relatively excellent display quality.

[0006] The invention provides a display device having excellent display quality.

[0007] The present invention provides an organic electroluminescent device, comprising a functional luminescent layer;

[0008] At no more than 0.01mA / cm 2 In the first target current density interval, the electron mobility V E and hole mobility V H Satisfy the requirements of formula 1:

[0009] |V E -V H |>1*10 -8 cm 2 / Vs Formula 1.

[0010] In the organic electroluminescent device as described above, the functional light-emitting layer is a red light-emitting layer and / or a green light-emitting layer.

[0011] The organic electroluminescent device as described above, wherein within the first target current density range, the electron mobility V E and hole mobility V H Satisfy the requirements of formula 2:

[0012] |V E -V H |>2*10 -8 cm 2 / Vs Formula 2.

[0013] The organic electroluminescent device as described above, wherein at a voltage greater than 0.01 mA / cm 2 And less than or equal to 5mA / cm 2 Within the target current sub-interval, the electron mobility V of the functional layer E and hole mobility V H Satisfy the requirements of formula 3:

[0014] |V E -V H |≤1*10 -8 cm 2 / Vs Formula 3.

[0015] The organic electroluminescent device as described above, wherein at a voltage greater than 5 mA / cm 2 Within the target current sub-interval, the electron mobility V of the functional layer E and hole mobility V H Satisfy the requirements of formula 4:

[0016] |V E -V H |≤3.5*10 -6 cm 2 / Vs Formula 4.

[0017] The organic electroluminescent device as described above, wherein at a voltage greater than 0.01 mA / cm 2 And less than or equal to 10mA / cm 2 In the second target current density interval, the electron mobility V of the functional light-emitting layer at the first current density E1 and hole mobility V H1 , and the electron mobility V of the functional light-emitting layer at the second current density E2 and hole mobility V H2 Satisfy the requirements of formula 5:

[0018] 0<|VE2 -V H2 |<|V E1 -V H1 Formula 5

[0019] Wherein, the first current density is smaller than the second current density.

[0020] The organic electroluminescent device as described above, wherein at a voltage greater than 0.01 mA / cm 2 And less than or equal to 10mA / cm 2 In the second target current density interval, the electron mobility V of the functional light-emitting layer at the third current density is E3 and V H3 Satisfy the requirements of formula 6:

[0021] |V E3 -V H3 |=0 Formula 6.

[0022] The organic electroluminescent device as described above, wherein the functional luminescent layer comprises a host material and a guest material;

[0023] The host material comprises a bipolar material, or the host material comprises at least one of a mixture of an electron donor material and an electron acceptor material, a mixture of the bipolar material and the electron donor material, and a mixture of the bipolar material and the electron acceptor material;

[0024] The guest material is a phosphorescent dye or a fluorescent dye;

[0025] Preferably, the electron donor material is a compound containing at least one electron donating group selected from carbazole, arylamino, silicon, fluorenyl, dibenzothienyl, and dibenzofuranyl aromatic groups; and / or,

[0026] The electron acceptor material is a compound containing at least one electron acceptor group selected from the group consisting of pyridyl, pyrimidyl, triazine, imidazole, o-phenanthroline, sulfone, heptazine, oxadiazole, cyano and diphenylphosphonyl.

[0027] In the organic electroluminescent device as described above, the functional light-emitting layer comprises a host material and a guest material, and the host material comprises at least one of the following materials:

[0028]

[0029] The guest material includes at least one of the following materials:

[0030]

[0031] Preferably, the functional light-emitting layer is composed of any one of the following combinations:

[0032] The first combination is composed of a host material represented by H1 and a guest material represented by D1;

[0033] The second combination consists of the host material shown in H2 and the guest material shown in D1;

[0034] The third combination consists of the host material shown in H3 and the guest material shown in D2;

[0035] The fourth combination consists of the host material represented by H4 and the guest material represented by D2;

[0036] The fifth combination consists of the host material shown in H5 and the guest material shown in D2;

[0037] The sixth combination consists of the host material represented by H6 and the guest material represented by D1;

[0038] The seventh combination consists of the host material shown in H7 and the guest material shown in D1;

[0039] The eighth combination is composed of a host material formed by mixing the compounds represented by H8 and H9 and a guest material represented by D1;

[0040] The ninth combination is composed of a host material formed by mixing the compounds represented by H8 and H10 and a guest material represented by D2;

[0041] The tenth combination is composed of a host material formed by mixing the compounds represented by H8 and H11 and a guest material represented by D3;

[0042] In the functional light-emitting layer, the mass percentage of the main material is 85-99%.

[0043] The present invention further provides a display device, comprising any one of the organic electroluminescent devices described above.

[0044] In the organic electroluminescent device of the present invention, the transmission performance of holes and electrons in the functional light-emitting layer at low current density is greatly different, thereby weakening its luminous efficiency at low grayscale. Therefore, the functional light-emitting layer of the present invention is not only easier to turn off at low grayscale, but also reduces the difference in the turn-on voltage between it and the light-emitting layer that is easily crosstalked (such as the blue light-emitting layer), avoiding the problem of light crosstalk caused by improper light emission of the light-emitting layer that is easily crosstalked to the light-emitting layer that is easily crosstalked, and improving the display quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The photoluminescence spectra of the organic electroluminescent devices of Example 1, Example 9 and Comparative Example 2 of the present invention are shown. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The first aspect of the present invention provides an organic electroluminescent device, comprising a light-emitting layer and an anode and a cathode respectively located on both sides of the light-emitting layer, wherein the light-emitting layer comprises a functional light-emitting layer.

[0048] Specifically, the cathode and the anode can be made of materials commonly used in the art. For example, the anode material can be made of transparent conductive oxide materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), and any combination thereof; the cathode can be made of metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and any combination thereof.

[0049] The functional light-emitting layer is described in detail below.

[0050] The functional luminescent layer of the present invention has a current of no more than 0.01 mA / cm 2 In the first target current density interval, the electron mobility V E and hole mobility V H Satisfy the requirements of formula 1:

[0051] |V E -V H |>1*10 -8 cm 2 / Vs Formula 1.

[0052] That is, the electron mobility and hole mobility of the functional light-emitting layer in the organic electroluminescent device of the present invention in the first target current density range have a large difference, specifically, the difference between the two is not less than 1*10 -8. Therefore, within the first target current interval, the differentiation between the electron mobility and the hole mobility of the functional light-emitting layer realizes the adjustment of the electron-hole recombination rate of the functional light-emitting layer, and ultimately makes the functional light-emitting layer show lower luminous efficiency. On the one hand, the reduction of luminous efficiency makes it easier to realize the shutdown of the functional light-emitting layer, avoiding the problem of unsatisfactory light color display due to the uncontrollable shutdown of the crosstalk-prone layer; on the other hand, the reduction of luminous efficiency of the functional light-emitting layer is conducive to reducing the start-up voltage of the functional light-emitting layer, thereby making the start-up voltage difference between the functional light-emitting layer and the crosstalk-prone light-emitting layer (such as the blue light-emitting layer) smaller, and ultimately greatly suppressing the crosstalk problem of the crosstalk-prone light-emitting layer on the crosstalk-prone light-emitting layer that exists at this stage. Therefore, the organic electroluminescent device of the present invention exhibits relatively excellent display quality at low grayscale (lower current density).

[0053] It can be understood that when the light-emitting layers susceptible to crosstalk in an organic electroluminescent device are all functional light-emitting layers, it is more conducive to reducing the adverse effects of uncontrollable shutdown of the light-emitting layers susceptible to crosstalk and light crosstalk on the display quality of the organic electroluminescent device.

[0054] The method for obtaining the electron mobility and the hole mobility of the present invention is as follows.

[0055] The light-emitting layer of the organic electroluminescent device is used to make a single electron device and a single hole device, and the single electron device and the single hole device are used as the detection objects to calculate the electron mobility and the hole mobility respectively, wherein the light-emitting layer composition of the single electron device and the single hole device is the same as the light-emitting layer composition of the organic electroluminescent device. Specifically, the single electron device includes an anode, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode in sequence; the single hole device includes an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron blocking layer and a cathode in sequence. It should be noted that, except for the light-emitting layer, the materials of other functional layers of the single electron device and the single hole device may be the same as or different from the materials of the corresponding functional layers of the organic electroluminescent device.

[0056] When testing electron mobility, the prepared single electron device was tested using an IVL test machine. The test range started from 0V and lasted until the current density reached 50mA / cm 2 The current density data of the single electron device with the change of voltage was obtained. The mobility was then calculated according to the following formula.

[0057]

[0058] In formula A, J is the current density, ε0 ​​is the vacuum dielectric constant, ε is the relative dielectric constant, μ is the mobility, V is the voltage, and d is the thickness of the film (the functional layer after removing the anode and cathode in the device).

[0059] Similarly, when detecting hole mobility, the above detection can be performed using a single hole device as the detection object, which will not be described in detail here.

[0060] It should be noted that the units of electron mobility and hole mobility in the present invention are cm 2 / Vs.

[0061] Since the red light emitting layer and / or the green light emitting layer can easily cause crosstalk to the blue light emitting layer, in a specific embodiment, the functional light emitting layer is a red light emitting layer and / or a green light emitting layer, thereby helping to reduce the crosstalk phenomenon of the red light emitting layer and / or the green light emitting layer, which are easy to crosstalk light emitting layers, with the light emitting layer that is easy to be crosstalked (blue light emitting layer), thereby improving the display quality of the organic electroluminescent device at low grayscale.

[0062] Furthermore, when the electron mobility V in the first target current density range is E and hole mobility V H When the requirements of Formula 2 are met, the difference in the transport and injection capabilities of holes and electrons in the functional light-emitting layer is greater, which is conducive to further weakening the adverse effects of the red and green light-emitting layers on the display quality, making the color rendering of the organic electroluminescent device more balanced and ideal.

[0063] |V E -V H |>2*10 -8 cm 2 / Vs Formula 2.

[0064] The organic electroluminescent device of the present invention has a functional light-emitting layer with lower light-emitting efficiency at low current density, which weakens the adverse effects of the red and green light-emitting layers on the display quality of the organic electroluminescent device at low grayscales. By improving the problems of the red and green light-emitting layers being difficult to shut down and the excessively high start-up voltage, the organic electroluminescent device can exhibit more excellent color rendering performance at low grayscales.

[0065] Furthermore, based on the requirements of organic electroluminescent devices for high luminous efficiency and low roll-off at high grayscale, the 2 And less than or equal to 5mA / cm 2 Within the target current sub-range, the electron mobility V E and hole mobility V H Satisfy the requirements of formula 3:

[0066] |V E -V H |≤1*10 -8 cm 2 / Vs Formula 3,

[0067] Obviously, at a value greater than 0.01 mA / cm 2And less than or equal to 5mA / cm 2 In the target current sub-range, the difference between the electron mobility and the hole mobility of the functional light-emitting layer satisfying Formula 3 is small. Therefore, at high grayscale (higher current density), the difference between the electron injection and transmission capabilities and the hole injection and transmission capabilities of the functional light-emitting layer is small, so the higher electron-hole recombination rate allows the system to have more excitons capable of energy level transition and energy transfer, which is conducive to achieving an improvement in the luminous efficiency of the organic electroluminescent device at high grayscale and a decrease in efficiency roll-off.

[0068] In addition, by limiting the difference between the electron mobility and the hole mobility of the functional layer at a higher grayscale, the requirement for high luminous efficiency of the organic electroluminescent device at a high grayscale can also be met. 2 Within the target current sub-interval, the electron mobility V of the functional layer E and hole mobility V H Satisfy the requirements of formula 4:

[0069] |V E -V H |≤3.5*10 -6 cm 2 / Vs Formula 4.

[0070] At more than 5mA / cm 2 Under high grayscale conditions, the difference between the electron mobility and the hole mobility of the functional layer satisfying Formula 4 is small, the electron transport and injection capabilities of the functional light-emitting layer are relatively balanced with the hole transport and injection capabilities, and the organic electroluminescent device exhibits satisfactory luminous efficiency by maintaining a high electron-hole recombination rate.

[0071] Furthermore, in a specific embodiment, at a temperature greater than 0.01 mA / cm 2 And less than or equal to 10mA / cm 2 In the second target current density interval, the electron mobility V of the functional light-emitting layer at the first current density E1 and hole mobility V H1 , the electron mobility V of the functional light-emitting layer at the second current density E2 and hole mobility V H2 Satisfy the requirements of formula 5:

[0072] 0<|V E2 -V H2 |<|V E1 -V H1 Formula 5

[0073] Wherein, the first current density is smaller than the second current density.

[0074] That is to say, within the second target current density range, as the current density gradually increases, the difference between the electron mobility and the hole mobility of the functional light-emitting layer gradually decreases. This gradually decreasing difference means that the electrons from the cathode and the holes from the anode can enter the functional light-emitting layer with more balanced and equal abilities and numbers to recombine one by one and generate excitons, avoiding the defect of unbalanced carriers in the functional light-emitting layer caused by the unbalanced electron and hole transport capabilities, and improving the utilization rate of carriers to make the organic electroluminescent device have better luminous efficiency at gradually increasing current density. The present invention does not limit the specific values ​​of the first current density and the second current density, as long as they are within the second target current density range.

[0075] In another specific embodiment, at greater than 0.01 mA / cm 2 And less than or equal to 10mA / cm 2 In the second target current density interval, the electron mobility V E3 and V H3 Satisfy the requirements of formula 6:

[0076] |V E3 -V H3 |=0 Formula 6

[0077] At this time, the transmission and injection capabilities of electrons are completely equal and balanced with the transmission and injection capabilities of holes, and electrons and holes are evenly and evenly distributed in the functional light-emitting layer and recombine one by one to generate excitons, thereby further improving the luminous efficiency of the organic electroluminescent device at high grayscale. The third current density is not unique, that is, in the second target current density range, it includes multiple different third current densities, and under these multiple different third current densities, the electron mobility and the hole mobility of the functional layer are equal.

[0078] It should be noted that when the 2 And less than or equal to 10mA / cm 2 Within the second target current density range, the organic electroluminescent device of the present invention can simultaneously meet the requirements of Formula 5 and Formula 6.

[0079] The present invention makes the electron mobility and hole mobility of the functional light-emitting layer have different differences at different current densities, thereby not only solving the problem that the red and green light-emitting layers of the organic electroluminescent device are difficult to shut down due to abnormal display at low grayscale and the crosstalk to the blue light-emitting layer, but also improves the luminous efficiency of the organic electroluminescent device at high grayscale, so that the organic electroluminescent device has excellent display quality.

[0080] The inventors have found that by controlling the composition of the functional light-emitting layer, it is possible to achieve differential control of the electron mobility and hole mobility of the functional light-emitting layer at different current densities. Of course, the present invention does not limit the specific composition of the functional light-emitting layer, and any functional light-emitting layer that meets the aforementioned definition is within the protection scope of the present invention.

[0081] Generally, the functional light-emitting layer includes a host material and a guest material. In specific applications, matching host materials and guest materials can be selected according to the difference relationship between different electron mobilities and hole mobilities of the functional light-emitting layer at different current densities.

[0082] In one embodiment, the host material comprises a bipolar material, or the host material comprises at least one of a mixture of an electron donor type material and an electron acceptor type material, a mixture of the bipolar material and the electron donor type material, and a mixture of the bipolar material and the electron acceptor type material;

[0083] The guest material is a phosphorescent dye or a fluorescent dye.

[0084] The above-mentioned bipolar material refers to a compound having both an electron-donating group and an electron-accepting group;

[0085] The above mixture refers to at least one of a mixture of a host material including a hole-type material (electron donor material) and an electron-type material (electron acceptor material), and a mixture of a bipolar material and a hole-type material or an electron-type material. Generally, the mass ratio of the two materials in the mixture is (1-9): (9-1), further (3-7): (7-3), and further (4-6): (6-4).

[0086] The electron donor material is a compound having hole transport properties and containing at least one electron donating group selected from carbazole, aromatic amino, silicon, fluorene, dibenzothienyl, and dibenzofuranyl aromatic groups.

[0087] Specifically, the electron donor material can be, but is not limited to, selected from compounds shown in one of the following structures:

[0088]

[0089]

[0090] Among them, the electron acceptor material is a compound with electron transport properties containing at least one electron acceptor group selected from pyridyl, pyrimidinyl, triazine, imidazole, o-phenanthroline, sulfone, heptazine, oxadiazole, cyano, and diphenylphosphonyl.

[0091] Specifically, the electron acceptor type material can be, but is not limited to, selected from compounds shown in one of the following structures:

[0092]

[0093]

[0094]

[0095] Exemplarily, the functional light-emitting layer is composed of any one of the following combinations:

[0096] The first combination is composed of a host material represented by H1 and a guest material represented by D1;

[0097] The second combination consists of the host material shown in H2 and the guest material shown in D1;

[0098] The third combination consists of the host material shown in H3 and the guest material shown in D2;

[0099] The fourth combination consists of the host material represented by H4 and the guest material represented by D2;

[0100] The fifth combination consists of the host material shown in H5 and the guest material shown in D2;

[0101] The sixth combination consists of the host material represented by H6 and the guest material represented by D1;

[0102] The seventh combination consists of the host material shown in H7 and the guest material shown in D1;

[0103] The eighth combination is composed of a host material formed by mixing the compounds represented by H8 and H9 and a guest material represented by D1;

[0104] The ninth combination is composed of a host material formed by mixing the compounds represented by H8 and H10 and a guest material represented by D2;

[0105] The tenth combination is composed of a host material formed by mixing the compounds represented by H8 and H11 and a guest material represented by D3;

[0106] In the functional light-emitting layer, the mass percentage of the main material is 85-99%.

[0107]

[0108]

[0109] It can be understood that the organic electroluminescent device of the present invention includes a blue light emitting layer in addition to the functional light emitting layer, and the blue light emitting layer is also located between the cathode and the anode, and is arranged in parallel with the functional light emitting layer according to the target light emitting color. The present invention refers to the combination of the functional light emitting layer and the blue light emitting layer as a light emitting layer.

[0110] In order to ensure the normal generation and transmission of holes and electrons, a hole region is provided between the anode and the light-emitting layer of the organic electroluminescent device of the present invention, and an electron region is provided between the cathode and the light-emitting layer.

[0111] The hole region may be a hole transport layer (HTL) of a single-layer structure, including a single-layer hole transport layer containing only one compound and a single-layer hole transport layer containing multiple compounds. According to the direction in which the anode points to the light-emitting layer, the hole region may also be a multilayer structure including at least two layers of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL) in sequence.

[0112] The present invention does not limit the selection of materials (including HIL, HTL and EBL) of the hole region, which can be materials commonly used in the art. For example, it can be selected from but not limited to phthalocyanine derivatives such as CuPc, conductive polymers or polymers containing conductive dopants such as polyphenylene ethylene, polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (Pani / CSA), polyaniline / poly(4-styrenesulfonate) (Pani / PSS), aromatic amine derivatives.

[0113] The electron region may be a single-layer electron transport layer (ETL), including a single-layer electron transport layer containing only one compound and a single-layer electron transport layer containing multiple compounds. According to the direction in which the cathode points to the light-emitting layer, the electron region may also be a multilayer structure including at least two layers of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL) in sequence.

[0114] The present invention does not limit the selection of materials for the electron region (including EIL, ETL and HBL), which can be materials commonly used in the art. For example, the materials for the electron transport layer and the hole blocking layer can be selected from, but not limited to, one or more combinations of ET-1 to ET-57 listed below.

[0115]

[0116]

[0117]

[0118] The electron injection layer material includes but is not limited to one or more combinations of the following: LiQ, LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca.

[0119] The thickness of each layer mentioned above can adopt the conventional thickness of these layers in the art.

[0120] The embodiment of the present invention further provides a display device, which includes the organic electroluminescent device provided above. The display device can specifically be a display device such as an OLED display, and any product or component with a display function such as a television, a digital camera, a mobile phone, a tablet computer, etc. that includes the display device. The display device has the same advantages as the above-mentioned organic electroluminescent device over the prior art, which will not be repeated here.

[0121] The organic electroluminescent device of the present invention is further described below through specific embodiments.

[0122] Examples 1-10 and Comparative Examples 1-3

[0123] Examples 1-10 and Comparative Examples 1-3 respectively provide an organic electroluminescent device, wherein the device structure comprises an ITO anode, a hole injection layer (3wt% E1+97wt% E2, )、hole transport layer (E2, )、blue light emitting layer (97wt% E3+3wt% E4, ), green light emitting layer (composition see Table 1, ), red light emitting layer (composition see Table 1, ) electron transport layer (50wt% E5+50wt% Liq, ), electron injection layer (material is Yb, ) and cathode (50wt% Mg+50wt% Ag). It should be noted that 3wt% E1+97wt% E2 means that the hole injection layer is composed of 3wt% E1 and 97wt% E2, with a thickness of

[0124] Among them, the compositions of the organic electroluminescent devices of Examples 1, 2, 6, 7, and 8 are basically the same as those of the organic electroluminescent device of Comparative Example 2 (the composition of the green light emitting layer is the same as that of Comparative Example 3), and the only difference is that the main materials in their respective red light emitting layers are different. The specific composition of the red light emitting layer is shown in Table 1.

[0125] The compositions of the organic electroluminescent devices of Examples 3, 4, 5, and 9 are basically the same as those of the organic electroluminescent device of Comparative Example 1 (the composition of the red light emitting layer is the same as that of Comparative Example 2). The only difference is that the main materials in their respective green light emitting layers are different. The specific composition of the green light emitting layer is shown in Table 1.

[0126] The compositions of the organic electroluminescent device of Example 10 and the organic electroluminescent device of Comparative Example 3 are basically the same (the composition of the red light emitting layer is the same as that of Comparative Example 2). The only difference is that the main materials in their respective green light emitting layers are different. The specific composition of the green light emitting layer is shown in Table 1.

[0127] It should be noted that, based on the above composition, Comparative Example 2 and Comparative Example 3 are actually the same organic electroluminescent device. In Table 1, Comparative Example 2 refers to the composition of the red light emitting layer of the organic electroluminescent device, and Comparative Example 3 refers to the composition of the green light emitting layer of the organic electroluminescent device; in addition, Examples 1, 2, 6, 7, and 8 in Table 1 actually correspond to the red light emitting layer in the organic electroluminescent device, and Examples 3, 4, 5, 9 and Comparative Example 1 in Table 1 actually correspond to the green light emitting layer in the organic electroluminescent device.

[0128]

[0129] The hole mobility and electron mobility of the red light emitting layer R or the green light emitting layer G in the above embodiments and comparative examples are obtained by testing the hole migration device HOD and the electron migration device EOD, and calculating them by formula A. The specific results are shown in Table 1. The structures of HOD and EOD are shown below.

[0130] HOD:

[0131]

[0132] EOD:

[0133]

[0134] Table 1

[0135]

[0136]

[0137] Test Example 1

[0138] The luminous efficiency of the organic electroluminescent devices in the embodiments and comparative examples was tested using Keithley 2602 electrical testing equipment. The results are shown in Table 2.

[0139] Table 2

[0140]

[0141] From Table 2, we can see that:

[0142] 1. Compared with Comparative Example 1, the composition of the green light emitting layer of Examples 3, 4, 5, and 9 of the present invention is conducive to reducing the green light emitting efficiency of the organic electroluminescent device at low grayscale, thereby suppressing the phenomenon of display quality degradation caused by green light crosstalk; in addition, at high grayscale, the green light emitting efficiency of Examples 3, 4, 5, and 9 is better than or equivalent to the green light emitting efficiency of Comparative Example 1; therefore, the organic electroluminescent devices based on Examples 3, 4, 5, and 9 of the present invention have better display quality and luminous efficiency;

[0143] Similarly, compared with Comparative Example 3, the composition of the green light emitting layer of Example 10 of the present invention is conducive to reducing the green light emitting efficiency of the organic electroluminescent device at low grayscale, thereby suppressing the phenomenon of display quality degradation caused by green light crosstalk; in addition, at high grayscale, the green light emitting efficiency of Example 10 is better than or equivalent to the green light emitting efficiency of Comparative Example 1; therefore, the organic electroluminescent device based on Example 10 of the present invention has better display quality and luminous efficiency;

[0144] 2. Compared with comparative example 2, the composition of the red light emitting layer of embodiments 1, 2, 6, 7, and 8 of the present invention is conducive to reducing the red light emitting efficiency of the organic electroluminescent device at low grayscale, thereby suppressing the phenomenon of display quality degradation caused by red light crosstalk; in addition, at high grayscale, the red light emitting efficiency of embodiments 1, 2, 6, 7, and 8 is better than or equivalent to the red light emitting efficiency of comparative example 2; therefore, the organic electroluminescent devices based on embodiments 1, 2, 6, 7, and 8 of the present invention have better display quality and luminescence efficiency.

[0145] Test Example 2

[0146] The photoluminescence spectrum of the organic electroluminescent devices of Comparative Example 2, Example 1 and Implementation 9 was tested at a low gray scale of G4 using a spectrum testing device CS200.

[0147] Figure 1 The photoluminescence spectra of the organic electroluminescent devices of Example 1, Example 9 and Comparative Example 2 of the present invention are shown.

[0148] Depend on Figure 1 It can be seen that, compared with Comparative Example 2, the red light crosstalk phenomenon of the organic electroluminescent device of Example 1 is significantly suppressed, and the green light crosstalk phenomenon of the organic electroluminescent device of Example 9 is significantly suppressed. Therefore, the functional light-emitting layer with low luminous efficiency at low grayscale of the present invention helps to reduce the red-green light crosstalk phenomenon of the organic electroluminescent device and improve the display quality of the organic electroluminescent device.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An organic electroluminescent device, characterized in that: including a functional luminescent layer; In the first target current density interval not greater than 0.01 mA / cm², the electron mobility V E and hole mobility V H Satisfy the requirements of formula 1: |V E -V H |>1 10 -8 cm² / Vs formula 1; In a second target current density interval greater than 0.01 mA / cm² and less than or equal to 10 mA / cm², the electron mobility V of the functional light-emitting layer at the first current density E1 and hole mobility V H1 , and the electron mobility V of the functional light-emitting layer at the second current density E2 and hole mobility V H2 Satisfy the requirements of formula 5: 0 < |V E2 -V H2 | < |V E1 -V H1 | Equation 5, wherein the first current density is less than the second current density; In the second target current density interval greater than 0.01 mA / cm² and less than or equal to 10 mA / cm², the electron mobility V E3 and V H3 Satisfy the requirements of formula 6: |V E3 -V H3 |=0 Formula 6; The functional luminescent layer comprises a host material and a guest material; The host material includes a bipolar material, or the host material includes at least one of a mixture of an electron donor material and an electron acceptor material, a mixture of the bipolar material and the electron donor material, and a mixture of the bipolar material and the electron acceptor material.

2. The organic electroluminescent device according to claim 1, characterized in that: The functional luminescent layer is a red luminescent layer and / or a green luminescent layer.

3. The organic electroluminescent device according to claim 1 or 2, characterized in that: In the first target current density range, the electron mobility V E and hole mobility V H Satisfy the requirements of formula 2: |V E -V H |>2 10 -8 cm² / Vs formula 2.

4. The organic electroluminescent device according to claim 3, characterized in that: In the target current density range greater than 0.01 mA / cm² and less than or equal to 5 mA / cm², the electron mobility V E and hole mobility V H Satisfy the requirements of formula 3: |V E -V H |≤1 10 -8 cm² / Vs formula 3.

5. The organic electroluminescent device according to claim 4, characterized in that: In the target current density range greater than 5 mA / cm², the electron mobility V E and hole mobility V H Satisfy the requirements of formula 4: |V E -V H |≤3.5 10 -6 cm² / Vs formula 4.

6. The organic electroluminescent device according to claim 1, characterized in that: The guest material is a phosphorescent dye or a fluorescent dye.

7. The organic electroluminescent device according to claim 1, characterized in that: The electron donor material is a compound containing at least one electron donating group selected from carbazole, arylamino, silicon, fluorenyl, dibenzothienyl, and dibenzofuranyl aryl groups; and / or, The electron acceptor material is a compound containing at least one electron acceptor group selected from the group consisting of pyridyl, pyrimidyl, triazine, imidazole, o-phenanthroline, sulfone, heptazine, oxadiazole, cyano and diphenylphosphonyl.

8. The organic electroluminescent device according to claim 1, characterized in that: The main material includes at least one of the following materials: ； The guest material includes at least one of the following materials: 。 9. The organic electroluminescent device according to claim 8, characterized in that: The functional light-emitting layer is composed of any one of the following combinations: The first combination consists of a host material represented by H1 and a guest material represented by D1; The second combination consists of the host material shown in H2 and the guest material shown in D1; The third combination consists of the host material shown in H3 and the guest material shown in D2; The fourth combination consists of the host material represented by H4 and the guest material represented by D2; The fifth combination consists of the host material shown in H5 and the guest material shown in D2; The sixth combination consists of the host material represented by H6 and the guest material represented by D1; The seventh combination consists of the host material shown in H7 and the guest material shown in D1; The eighth combination is composed of a host material formed by mixing the compounds represented by H8 and H9 and a guest material represented by D1; The ninth combination is composed of a host material formed by mixing the compounds represented by H8 and H10 and a guest material represented by D2; The tenth combination is composed of a host material formed by mixing the compounds represented by H8 and H11 and a guest material represented by D3; In the functional light-emitting layer, the mass percentage of the main material is 85-99%.

10. A display device, characterized in that: An organic electroluminescent device comprising any one of claims 1 to 9.

Images