QLED device and application thereof

Abstract

The invention provides a QLED device and application thereof. The QLED device comprises a light-emitting layer, and the light-emitting layer comprises a first light-emitting layer, an exciton barrier layer and a second light-emitting layer which are sequentially stacked. The material of the first light-emitting layer comprises a first main body matrix and a dye; the dye comprises a blue light dye and / or a yellow light dye. According to the invention, through the design of the light-emitting layer of the QLED device and the design of the material of the first light-emitting layer, the QLED device with relatively high light-emitting efficiency and relatively high white light color rendering index is prepared, and the QLED device is suitable for preparing liquid crystal televisions with excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of light emitting diode devices, and specifically relates to a QLED device and its application. Background Art

[0002] The backlight sources of current high-end liquid crystal display (LCD) televisions (TVs) utilize color-converting white organic light-emitting diodes (WLEDs), which consist of blue LEDs, green LEDs, and quantum dot color conversion films attached to red LEDs. High-energy blue light excites red and green quantum dot materials, which then emit narrowband green and red light. This light then mixes with the blue LED light to create high-quality white light. Unlike traditional LCD backlight units, this white light achieves the wide color gamut of LCDs, enhancing their color expression.

[0003] Therefore, how to provide a new device structure to solve the problems of low efficiency and low CRI of white light quantum dot devices has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In response to the shortcomings of the prior art, the present invention aims to provide a QLED device and its application. By designing the light-emitting layer of the QLED device and further designing the material of the first light-emitting layer, the present invention produces a QLED device with high luminous efficiency and a high white light color rendering index, suitable for the production of high-performance devices such as liquid crystal televisions.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a QLED device, comprising a light-emitting layer, wherein the light-emitting layer comprises a first light-emitting layer and a second light-emitting layer stacked together;

[0007] The material of the first light-emitting layer includes a first host matrix and a dye;

[0008] The dye includes a blue light-emitting dye and / or a yellow light-emitting dye.

[0009] Color-converted WLEDs exhibit low luminous efficiency due to the reabsorption of high-energy blue light photons by narrow-bandgap quantum dot materials, internal light scattering, and photobleaching. Therefore, in order to improve the luminous efficiency, electroluminescent WLEDs based on a mixture of quantum dot materials with different luminescent colors have attracted the research interest of researchers. However, compared with green and red quantum dot materials, the electroluminescent efficiency of blue quantum dot materials is relatively low; in addition, the narrow-band emission of quantum dot materials of different colors increases the spectral spacing, thereby reducing the color rendering index (CRI) of white light. In the present invention, through the design of the light-emitting layer of the QLED device, further through the design of the first light-emitting layer material, and through the use of blue light dyes and / or yellow light dyes, a QLED device with high luminous efficiency and high white light color rendering index is prepared, which is suitable for the preparation of devices such as liquid crystal televisions with excellent performance.

[0010] In the present invention, the blue light dye has a multiple resonance effect, which can realize the localization of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) on adjacent atoms, thereby obtaining a small electron exchange energy, and realizing the effective utilization of electrically injected triplet excitons, achieving 100% exciton utilization, improving the blue light luminescence efficiency, and thus improving the efficiency of white light QLED devices. The localization of the frontier molecular orbitals on adjacent atoms also suppresses the vibration coupling between the ground state and the excited state, which can realize narrow-spectrum emission and enhance color expression.

[0011] In the present invention, the yellow dye has a multiple resonance effect, which can achieve the localization of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) on adjacent atoms, thereby obtaining a small electron exchange energy, and can achieve effective utilization of electrically injected triplet excitons, achieving 100% exciton utilization. The localization of the frontier molecular orbital on adjacent atoms also suppresses the vibrational coupling between the ground state and the excited state, which can achieve narrow-spectrum emission and enhance color expression. The introduction of the yellow multi-resonance dye can significantly reduce the spacing between the electroemission spectra of different dyes, thereby improving the white light CRI.

[0012] In the present invention, the QLED device is a quantum dot light emitting diode device.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] As a preferred technical solution of the present invention, the doping concentration of the dye in the first light-emitting layer is 1wt% to 8wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%, etc.

[0015] By controlling the dye doping concentration in the first light-emitting layer within a specific range, the present invention can produce a QLED device with excellent performance. If the dye doping concentration is too low, the resulting QLED device will have low luminous efficiency and white light rendering index. If the dye doping concentration is too high, it will cause exciton quenching at high current density, resulting in poor efficiency stability of the QLED device and low luminous efficiency.

[0016] Preferably, the doping concentration of the blue light dye in the first light-emitting layer is 0.5wt% to 8wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%, etc.

[0017] Preferably, the doping concentration of the yellow dye in the first light-emitting layer is 0.5wt% to 8wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%, etc.

[0018] Preferably, the dye is a blue dye or a combination of a yellow dye and a blue dye, further preferably a combination of a yellow dye and a blue dye. A lower doping concentration can prevent the blue light emission in the first light-emitting layer from being completely quenched by the yellow dye, while reducing the spacing between different emission peaks and improving the CRI of white light.

[0019] In the present invention, a blue light dye or a combination of a yellow light dye and a blue light dye is selected as the dye of the first light-emitting layer, which can further improve the overall performance of the QLED device.

[0020] As a preferred technical solution of the present invention, the blue light dye is selected from compounds having a multiple resonance effect.

[0021] Preferably, the blue light dye comprises a compound having a structure shown in the following formula I:

[0022]

[0023] Wherein, R1 is selected from C1-C10 alkyl;

[0024] R2 and R3 are each independently selected from substituted or unsubstituted C6-C12 aryl groups;

[0025] R4 and R5 are each independently selected from a C1-C10 alkyl group, a substituted or unsubstituted C6-C12 aryl group, or a substituted or unsubstituted C3-C15 heteroaryl group; R4 may be connected to the connected phenyl ring A via a single bond or -O-; and R5 may be connected to the connected phenyl ring B via a single bond or -O-;

[0026] The substituents in R2-R5 are each independently selected from C1-C10 alkyl groups.

[0027] In the present invention, C1-C10 can be C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10 (the same below).

[0028] C6-C12 can be C6, C8, C10 or C12, etc. (the same below).

[0029] C3-C15 can be C3, C5, C7, C10, C12 or C15, etc. (the same below).

[0030] Preferably, R1 is selected from any one of methyl, ethyl, n-propyl, isopropyl or butyl, more preferably isopropyl.

[0031] R2 and R3 are each independently selected from phenyl, naphthyl, biphenyl, more preferably The dotted lines indicate the junction sites.

[0032] R4 and R5 are each independently selected from methyl, ethyl, n-propyl, isopropyl, butyl, phenyl, naphthyl, biphenyl, Any one of, more preferably isopropyl, phenyl, In any one of the above, the dotted line indicates the connection site, R4 can be connected to the connected benzene ring A through a single bond or -O-, and R5 can be connected to the connected benzene ring B through a single bond or -O-.

[0033] Preferably, the blue light dye is selected from at least one of compounds a1-a9:

[0034]

[0035] As a preferred technical solution of the present invention, the yellow dye includes a compound having a structure shown in the following formula II, formula III or formula IV:

[0036]

[0037] Wherein, X1 to X6 are each independently selected from carbonyl or R A 、R B Each is independently selected from C1-C5 alkyl, and the dotted line indicates the attachment site;

[0038] R 21 、R 31 、R 41 、R 42 Each independently selected from C1-C10 alkyl, C6-C15 aryl;

[0039] R 22 、R 23 、R 32 、R 33 、R 43 、R 44 are each independently selected from H, C1-C10 alkyl, substituted or unsubstituted C6-C15 aryl, substituted or unsubstituted C5-C30 heteroaryl, wherein R 43 It can be connected to the benzene ring C through a single bond.

[0040] In the present invention, C1-C5 can be C1, C2, C3, C4 or C5 (the same below).

[0041] C6-C15 can be C6, C7, C8, C10, C12 or C15 (the same below).

[0042] C5-C30 can be C5, C7, C10, C12, C18, C24 or C30 (the same below).

[0043] Preferably, X1 and X2 are carbonyl groups.

[0044] Preferably, each of X3 to X6 is independently selected from a carbonyl group or Dashed lines indicate the junction sites.

[0045] Preferably, the R 21 、R 31 、R 41 、R 42 Each is independently selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, phenyl, naphthyl and biphenyl, and is more preferably isopropyl or phenyl.

[0046] Preferably, the R 21 It is isopropyl.

[0047] Preferably, the R 31 、R 41 、R 42 It is phenyl.

[0048] Preferably, the R 22 、R 23 、R 32 、R 33 、R 43 、R 44 Each is independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, phenyl, naphthyl, biphenyl, carbazolyl, At least one of the R 43 It can be connected to the benzene ring C through a single bond.

[0049] Preferably, the R 22 、R 23 、R 32 、R 33 Each independently selected from H or

[0050] Preferably, the R 43 、R 44 Each independently selected from H, isopropyl, carbazolyl or At least one of the R 43 It can be connected to the benzene ring C through a single bond.

[0051] Preferably, the yellow dye is selected from at least one of compounds b1-b9:

[0052]

[0053] In the present invention, by selecting a specific compound as a blue light dye and a specific compound as a yellow light dye, a QLED device with excellent performance can be prepared.

[0054] It should be noted that the present invention does not have any special restrictions on the preparation methods of the compounds represented by Formula I to Formula IV, and any commonly used preparation methods in the art are applicable.

[0055] As a preferred technical solution of the present invention, the band gap of the first host matrix is ​​≥3.5eV (for example, it can be 3.5eV, 3.55eV, 3.6eV, 3.65eV, 3.7eV, 3.75eV, 3.8eV, 3.85eV, 3.9eV, 3.95eV or 4.0eV, etc.), and the lowest triplet energy level (T1) is ≥3.2eV (for example, it can be 3.2eV, 3.3eV, 3.64eV, 3.5eV, 3.6eV, 3.7eV, 3.8eV, 3.9eV or 4.0eV, etc.).

[0056] In the present invention, by selecting a material with a wide band gap and a lowest triplet energy level (T1) ≥ 3.2 eV as the first host matrix, the energy backtransfer of high-energy blue light excitons to the first host matrix can be effectively avoided. In addition, the host matrix has a high hole mobility and is used in combination with a specific dye to prepare a QLED device with high luminous efficiency and high white light color rendering index.

[0057] It should be noted that there is no special restriction on the specific selection of the first host matrix in the present invention, and any material in the art that satisfies the requirements of a band gap ≥ 3.5 eV and a lowest triplet energy level ≥ 3.2 eV is applicable.

[0058] Preferably, the thickness of the first light-emitting layer is 15 to 40 nm, for example, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm or 40 nm.

[0059] As a preferred technical solution of the present invention, the material of the second light-emitting layer includes a second host matrix, a red light quantum dot material and a green light quantum dot material.

[0060] It should be noted that there is no particular limitation on the specific selection of the second host matrix in the present invention, and any host matrix commonly used in the art is applicable.

[0061] As a preferred technical solution of the present invention, the doping concentration of the red light quantum dot material in the second light-emitting layer is 5wt% to 10wt%, for example, it can be 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, etc.

[0062] Preferably, the doping concentration of the green light quantum dot material in the second light-emitting layer is 20wt% to 40wt%, for example, it can be 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, 32wt%, 34wt%, 36wt%, 38wt% or 40wt%, etc.

[0063] In the present invention, the doping concentrations of the green light quantum dot material and the red light quantum dot material are designed, and the doping concentration of the green light quantum dot material is further designed to be much higher than the doping concentration of the red light quantum dot material. Among them, the lower red light doping concentration can avoid the quenching of the green light quantum dot luminescence by the low-energy red light quantum dot emission, and finally a QLED device with excellent performance is prepared.

[0064] It should be noted that there is no special restriction on the specific selection of green quantum dot materials and red quantum dot materials in the present invention, and the green quantum dot materials and red quantum dot materials commonly used in the art are applicable.

[0065] Preferably, the thickness of the second light-emitting layer is 15 to 40 nm, for example, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm or 40 nm.

[0066] As a preferred technical solution of the present invention, an exciton blocking layer can be further provided between the first light-emitting layer and the second light-emitting layer.

[0067] Preferably, the lowest triplet energy level (T1) of the material of the exciton blocking layer is ≥3.2 eV, for example, it can be 3.2 eV, 3.3 eV, 3.64 eV, 3.5 eV, 3.6 eV, 3.7 eV, 3.8 eV, 3.9 eV or 4.0 eV.

[0068] Preferably, the thickness of the exciton blocking layer is 5 nm to 10 nm, for example, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm or 10 nm.

[0069] In the present invention, by selecting a material with a lowest triplet energy level (T1) ≥ 3.2 eV to prepare the exciton-blocking layer and controlling its thickness within a specific range, the resonant energy transfer of high-energy blue excitons in the first luminescent layer to the second luminescent layer can be effectively prevented, ensuring that the blue excitons are not quenched by the low-energy second luminescent layer. If the lowest triplet energy level (T1) of the exciton-blocking layer material is too low, it is easy to quench the excitons in the luminescent layer, resulting in lower luminous efficiency; if the thickness of the exciton-blocking layer is too small, it is difficult to effectively prevent the leakage of high-energy excitons into green or red light; if the thickness of the exciton-blocking layer is too large, effective resonant energy transfer is difficult to occur, making it difficult to synthesize white light.

[0070] The material of the exciton blocking layer is selected from TSPO1.

[0071] As a preferred technical solution of the present invention, the QLED device further includes a first electrode and an electron transport layer stacked on one side of the light-emitting layer, and further includes a hole transport layer, a second electrode and a substrate stacked on the other side of the light-emitting layer;

[0072] The first light-emitting layer in the light-emitting layer is attached to the hole transport layer, and the second light-emitting layer in the light-emitting layer is attached to the electron transport layer.

[0073] That is, the QLED device provided by the present invention includes a first electrode, an electron transport layer, a second light-emitting layer, an exciton blocking layer, a first light-emitting layer, a hole transport layer, a second electrode and a substrate, which are stacked in sequence;

[0074] The first electrode is a cathode, and the second electrode is an anode;

[0075] Alternatively, the first electrode is an anode and the second electrode is a cathode.

[0076] It should be noted that in the present invention, there are no special restrictions on the selection of materials and thickness design of the cathode, electron transport layer, hole transport layer, anode and substrate. Commonly used materials and thicknesses in the art are applicable, including but not limited to:

[0077] Cathode: Material selected from Ag, Al, IZO, etc., with a thickness of 20 to 200 nm, for example, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm or 200 nm;

[0078] Electron transport layer: material selected from ZnO or ZnMgO; thickness is 40 to 100 nm, for example, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm;

[0079] Hole transport layer: the material is selected from PEDOT:PSS, with a thickness of 20 to 40 nm, for example, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm or 40 nm;

[0080] Anode: The material is selected from ITO or ITO / Ag / ITO, IZO, with a thickness of 80 to 100 nm, for example, 80 nm, 82 nm, 84 nm, 86 nm, 88 nm, 90 nm, 92 nm, 94 nm, 96 nm, 98 nm or 100 nm;

[0081] Substrate: The material is selected from glass, and the thickness is 0.2-1 mm, for example, it can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm.

[0082] It should also be noted that the present invention has no special restrictions on the preparation method of QLED devices, and commonly used methods in the field are applicable, including but not limited to:

[0083] The method for preparing the QLED device specifically includes the following steps:

[0084] The ITO conductive glass substrate was cleaned with acetone, cleaning solution, and secondary deionized water in sequence, and then transferred to a 120°C oven for drying. The dried ITO glass substrate was then placed in a UV / Ozone atmosphere for 40 minutes, and then spin-coated with the hole transport layer material at a speed of 5000 rpm for 40 seconds. The substrate was then transferred to a 120°C oven for 45 minutes, and the dried substrate was quickly transferred to a vacuum evaporator and evacuated to a pressure of less than 4×10 -4 At Pa, the materials for the first light-emitting layer and the exciton blocking layer were evaporated, and the evaporated substrate was transferred to a glove box, the materials for the second light-emitting layer were spin-coated, and finally the materials for the electron transport layer, ZnO, and the metal electrode were evaporated.

[0085] In a second aspect, the present invention provides a device comprising the QLED device as described in the first aspect, wherein the device includes a liquid crystal television, an OLED television, and a white light lighting device.

[0086] Compared with the prior art, the present invention has the following beneficial effects:

[0087] In the present invention, by designing the light-emitting layer of the QLED device, further by designing the first host matrix and dye in the first light-emitting layer, and in combination with an exciton blocking layer with a specific thickness, a QLED device with high luminous efficiency and high white light color rendering index is prepared, which is suitable for preparing LCD TVs, OLED TVs, and white light lighting devices with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 2 is a schematic structural diagram of a QLED device provided by an embodiment of the present invention;

[0089] Among them, 1-first electrode, 2-electron transport layer, 3-light-emitting layer, 31-second light-emitting layer, 32-exciton blocking layer, 33-first light-emitting layer, 4-hole transport layer, 5-second electrode, 6-substrate. DETAILED DESCRIPTION

[0090] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0091] The sources of some components in the following examples and comparative examples are shown in Table 1 below:

[0092] Table 1

[0093]

[0094] Examples 1-16

[0095] Examples 1-16 provide a QLED device, respectively. The schematic structural diagram of the QLED device is shown in FIG. Figure 1 As shown, it includes a first electrode 1, an electron transport layer 2, a light-emitting layer 3, a hole transport layer 4, a second electrode 5 and a substrate 6 which are stacked in sequence;

[0096] The light-emitting layer 3 includes a second light-emitting layer 31, an exciton blocking layer 32, and a first light-emitting layer 33;

[0097] The first electrode 1 is made of Al and has a thickness of 150 nm;

[0098] The material of the electron transport layer 2 is ZnO, and the thickness is 40nm;

[0099] The specific composition of the second light-emitting layer 31 is shown in Table 2 or Table 3 below, and the thickness is 20 nm;

[0100] The material of the exciton blocking layer 32 is B1, and the thickness is shown in Table 2 or Table 3 below;

[0101] The specific composition of the first light-emitting layer 33 is shown in Table 2 or Table 3 below. The thickness is 30 nm.

[0102] The hole transport layer 4 is made of PEDOT:PSS with a thickness of 30 nm.

[0103] The second electrode 5 is ITO with a thickness of 100 nm;

[0104] The substrate 6 is a glass substrate with a thickness of 0.5 mm.

[0105] The specific preparation method of the above-mentioned QLED device is as follows:

[0106] The ITO conductive glass substrate was cleaned with acetone, cleaning solution, and secondary deionized water in sequence, and then transferred to a 120°C oven for drying. The dried ITO glass substrate was then placed in a UV / Ozone atmosphere for 40 minutes, and then spin-coated with PEDOT:PSS (P4083) at a speed of 5000 rpm for 40 seconds. It was then transferred to a 120°C oven for 45 minutes. The dried substrate was quickly transferred to a vacuum evaporator and evacuated to a pressure of less than 4×10 -4 Pa, the first light-emitting layer and the exciton blocking layer were evaporated, and the evaporated substrate was transferred to the glove box, and the second light-emitting layer and the electron transport layer were spin-coated. Finally, the electron transport layer ZnO (40 nm) and the metal electrode were evaporated.

[0107] Table 2

[0108]

[0109]

[0110] Table 3

[0111]

[0112] Comparative Example 1

[0113] Comparative Example 1 uses the same device preparation method as the embodiment; the only difference is that the first light-emitting layer of the comparative example uses a blue light quantum dot material; the blue light quantum dot material is a relatively conventional blue light quantum dot material such as CdSe.

[0114] The performance of the QLED devices provided in the above embodiments and comparative examples was tested, and the specific testing method is as follows:

[0115] Luminous efficiency: The current density, voltage, brightness, and efficiency characteristics of electroluminescent devices were measured using a Keithley source meter module in an atmospheric environment. The electroluminescent spectrum and color coordinates were measured using a CS2000.

[0116] White light color rendering index: measured by color rendering index tester, model HPCS320D.

[0117] The above performance test structure is shown in Table 4 below:

[0118] Table 4

[0119]

[0120] From the above content, it can be seen that in the present invention, through the design of the light-emitting layer of the QLED device, further through the design of the first host matrix and dye in the first light-emitting layer, and in combination with an exciton blocking layer with a specific thickness, a QLED device with high luminous efficiency and high white light color rendering index is prepared. It is suitable for the preparation of high-performance liquid crystal televisions and other devices, with a luminous efficiency of 35 to 56 cd / A and a white light color rendering index of 69 to 92.

[0121] It can be seen from the data of Examples 1-6 that the performance of the QLED device can be further improved by selecting a blue dye or a combination of a blue dye and a yellow dye as the dye of the first light-emitting layer in the present invention. The blue dye has a multiple resonance effect, which can realize the localization of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) on adjacent atoms, thereby obtaining a small electron exchange energy, and can realize the effective utilization of the electrically injected triplet excitons, achieve 100% exciton utilization, improve the blue light luminescence efficiency, and thus improve the efficiency of the white light QLED device; the localization of the frontier molecular orbital on the adjacent atoms also suppresses the vibration coupling between the ground state and the excited state, can realize narrow spectrum generation emission, and improve color expression; in addition, the doping concentration of the blue dye is 0.5wt% to 8wt%. The lower doping concentration can effectively avoid exciton quenching at high current density and improve efficiency stability. The first light-emitting layer is also doped with a yellow dye, and the doping concentration of the yellow dye is between 0.5 and 8 wt%. The lower doping concentration can prevent the blue light emission in the first light-emitting layer from being completely quenched by the yellow dye; the yellow dye has a multiple resonance effect, which can realize the localization of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) on adjacent atoms, thereby obtaining a small electron exchange energy, and can realize the effective utilization of the electrically injected triplet excitons, achieving 100% exciton utilization rate. The localization of the frontier molecular orbital on the adjacent atoms also suppresses the vibration coupling between the ground state and the excited state, which can realize narrow-spectrum emission and enhance color expression; the introduction of the yellow multiple resonance dye can significantly reduce the spacing between the electroemission spectra of different dyes, thereby improving the white light CRI.

[0122] As can be seen from the data of Examples 1 and 7-11, in the present invention, by controlling the doping concentration of the dye in the first light-emitting layer within a specific range and combining it with a first host matrix having a wide band gap (band gap ≥ 3.5 eV) and a lowest triplet energy level (T1) ≥ 3.2 eV, the performance of the QLED device can be further improved, effectively avoiding the energy back transfer of high-energy blue light excitons to the host matrix, and the host matrix has a high hole mobility.

[0123] The data from Examples 1 and 12-15 demonstrate that, by controlling the thickness of the exciton-blocking layer within a specific range, the present invention can produce a QLED device with high luminous efficiency and a high white light color rendering index. The exciton-blocking layer also has a high lowest triplet energy level of ≥3.2 eV and a thickness of 5-10 nm. This effectively prevents resonant energy transfer of high-energy blue excitons in the first luminescent layer to the second luminescent layer, ensuring that the blue excitons are not quenched by the lower-energy second luminescent layer.

[0124] The data from Examples 1 and 16 demonstrate that by controlling the doping concentrations of the green and red quantum dot materials in the second light-emitting layer within a specific range, the present invention can further improve QLED device performance. A lower red doping concentration can prevent quenching of the green quantum dot emission by the low-energy red quantum dot emission.

[0125] It can be seen from the data of Examples 1-16 and Comparative Example 1 that by designing the light-emitting layer of the QLED device, a QLED device with higher luminous efficiency and higher white light color rendering index was prepared.

[0126] In summary, in the present invention, through the design of the light-emitting layer of the QLED device, further through the design of the first host matrix and dye in the first light-emitting layer, and in combination with an exciton blocking layer with a specific thickness, a QLED device with high luminous efficiency and high white light color rendering index is prepared, which is suitable for the preparation of LCD TVs, OLED TVs, and white light lighting devices with excellent performance.

[0127] The applicant declares that the present invention is intended to illustrate the detailed structural features of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed structural features. This does not mean that the present invention must rely on the above-described detailed structural features in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A QLED device, characterized in that: The QLED device includes a light-emitting layer, wherein the light-emitting layer includes a first light-emitting layer and a second light-emitting layer stacked together; The material of the first light-emitting layer includes a first host matrix and a dye; The dye includes a blue light-emitting dye and / or a yellow light-emitting dye.

2. The QLED device according to claim 1, wherein The doping concentration of the dye in the first light-emitting layer is 1 wt% to 8 wt%; Preferably, the doping concentration of the blue dye in the first light-emitting layer is 0.5 wt % to 8 wt %; Preferably, the doping concentration of the yellow dye in the first light-emitting layer is 0.5 wt % to 8 wt %; Preferably, the dye is a blue dye or a combination of a yellow dye and a blue dye, more preferably a combination of a yellow dye and a blue dye.

3. The QLED device according to claim 1 or 2, wherein: The blue light dye is selected from compounds having a multiple resonance effect; Preferably, the blue light dye comprises a compound having a structure shown in the following formula I: Wherein, R1 is selected from C1-C10 alkyl; R2 and R3 are each independently selected from substituted or unsubstituted C6-C12 aryl groups; R4 and R5 are each independently selected from a C1-C10 alkyl group, a substituted or unsubstituted C6-C12 aryl group, or a substituted or unsubstituted C3-C15 heteroaryl group; R4 may be connected to the connected phenyl ring A via a single bond or -O-; and R5 may be connected to the connected phenyl ring B via a single bond or -O-; The substituents in R2-R5 are each independently selected from C1-C10 alkyl groups; Preferably, R1 is selected from any one of methyl, ethyl, n-propyl, isopropyl or butyl, more preferably isopropyl; R2 and R3 are each independently selected from phenyl, naphthyl, biphenyl, more preferably The dotted lines indicate the junction sites; R4 and R5 are each independently selected from methyl, ethyl, n-propyl, isopropyl, butyl, phenyl, naphthyl, biphenyl, Any one of, more preferably isopropyl, phenyl, Any one of the compounds a1-a9, wherein the dotted line represents the connection site, R4 can be connected to the connected benzene ring A through a single bond or -O-, and R5 can be connected to the connected benzene ring B through a single bond or -O-; preferably, the blue light dye includes at least one of compounds a1-a9:

4. The QLED device according to any one of claims 1 to 3, wherein: The yellow dye includes a compound having a structure shown in the following formula II, formula III or formula IV: Wherein, X1 to X6 are each independently selected from carbonyl or R A 、R B Each is independently selected from C1-C5 alkyl, and the dotted line indicates the attachment site; R 21 、R 31 、R 41 、R 42 Each independently selected from C1-C10 alkyl, C6-C15 aryl; R 22 、R 23 、R 32 、R 33 、R 43 、R 44 are each independently selected from H, C1-C10 alkyl, substituted or unsubstituted C6-C15 aryl, substituted or unsubstituted C5-C30 heteroaryl, wherein R 43 It can be connected to the benzene ring C through a single bond; Preferably, X1 and X2 are carbonyl groups; Preferably, each of X3 to X6 is independently selected from a carbonyl group or Dashed lines indicate junction sites; Preferably, the R 21 、R 31 、R 41 、R 42 Each independently selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, phenyl, naphthyl or biphenyl, more preferably isopropyl or phenyl; Preferably, the R 21 isopropyl; Preferably, the R 31 、R 41 、R 42 is phenyl; Preferably, the R 22 、R 23 、R 32 、R 33 、R 43 、R 44 Each is independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, phenyl, naphthyl, biphenyl, carbazolyl, At least one of the R 43 It can be connected to the benzene ring C through a single bond; Preferably, the R 22 、R 23 、R 32 、R 33 Each independently selected from H or Preferably, the R 43 、R 44 Each independently selected from H, isopropyl, carbazolyl or At least one of the R 43 It can be connected to the benzene ring C through a single bond; preferably, the yellow dye includes at least one of compounds b1-b9:

5. The QLED device according to any one of claims 1 to 4, wherein: The band gap of the first host matrix is ​​≥3.5 eV, and the lowest triplet energy level is ≥3.2 eV; Preferably, the thickness of the first light-emitting layer is 15-40 nm.

6. The QLED device according to any one of claims 1 to 5, wherein: The materials of the second light-emitting layer include a second host matrix, a red light quantum dot material and a green light quantum dot material.

7. The QLED device according to claim 6, wherein: The doping concentration of the red light quantum dot material in the second light-emitting layer is 5wt% to 10wt%; Preferably, the doping concentration of the green light quantum dot material in the second light-emitting layer is 20 wt% to 40 wt%; Preferably, the thickness of the second light-emitting layer is 15-40 nm.

8. The QLED device according to any one of claims 1 to 7, wherein: An exciton blocking layer is further provided between the first light-emitting layer and the second light-emitting layer; Preferably, the lowest triplet energy level of the material of the exciton blocking layer is ≥3.2 eV; Preferably, the thickness of the exciton blocking layer is 5 nm to 10 nm.

9. The QLED device according to any one of claims 1 to 8, wherein: The QLED device further includes a first electrode and an electron transport layer stacked on one side of the light-emitting layer, and a hole transport layer, a second electrode and a substrate stacked on the other side of the light-emitting layer; The first light-emitting layer in the light-emitting layer is adhered to the hole transport layer, and the second light-emitting layer in the light-emitting layer is adhered to the electron transport layer.

10. A device comprising the QLED device according to any one of claims 1 to 9, characterized in that: The devices include liquid crystal televisions, OLED televisions, and white light lighting devices.

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