A large-area color temperature tunable light-emitting device by transfer printing over horizontal interdigital electrodes and a preparation method thereof

Abstract

This invention belongs to the field of organic optoelectronic materials applications and discloses a large-area color-temperature tunable light-emitting device and its fabrication method, which involves transfer printing above horizontal interdigitated electrodes. The main feature of this device is that it has two or more parallel-arranged complementary color-emitting regions. The emission spectrum can be controllably adjusted and its stability improved by regulating the material composition and spacing of the complementary color-emitting regions in the horizontal direction. Furthermore, this invention does not require complex fine masking processes. It uses a template method for transfer printing to pattern one light-emitting region in the horizontal direction and align it with the bottom interdigitated electrode. The other light-emitting region can be grown on a large area without masking or patterning, thus achieving controllable fabrication of flexible, color-temperature tunable, large-area white light panels.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials application, specifically relating to a method for preparing and applying a large-area color temperature adjustable light-emitting device by transfer printing above horizontal interdigitated electrodes. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have attracted continuous attention from researchers in academia and industry due to their unique advantages such as flexibility, low power consumption, and wide color gamut. Currently, OLED technology not only has important applications in the display field but can also be used in the lighting field to achieve flexible, uniform, and healthy light sources. However, conventional white light devices generally have multiple light-emitting layers stacked vertically. Because the electron and hole injection performance varies with the driving voltage, long-term operation can lead to color drift. Therefore, it is necessary to develop a light-emitting device structure with good spectral stability and in-situ tunability. Summary of the Invention

[0003] This invention aims to solve the problem of spectral drift of existing white light devices over time. To realize large-area, spectrally stable light-emitting devices, this invention provides a low-cost, high-efficiency, and highly spectrally stable complementary-color white light device. It relates to a method for preparing white organic light-emitting electroluminescent devices based on transfer printing technology without relying on vacuum evaporation technology.

[0004] The large-area color temperature adjustable light-emitting device with transfer printing above horizontal interdigitated electrodes includes a substrate, interdigitated anode, hole injection layer, hole transport layer, red-orange light-emitting layer, blue light-emitting layer, electron transport layer, electron injection layer, and cathode; characterized in that the red-orange light-emitting layer and the blue light-emitting layer are prepared layer by layer by transfer printing to form two horizontally parallel complementary color light-emitting regions, and white light is formed by the complementarity of sky blue light and red-orange light; The method for fabricating a large-area color temperature adjustable light-emitting device by transfer printing above horizontal interdigitated electrodes includes the following steps: (1) The electrodes on the substrate are rapidly ablated by laser to obtain patterned electrodes A and B, forming a strip-shaped interdigitated anode. After ultrasonic cleaning with acetone, ethanol and deionized water respectively, the substrate is dried with nitrogen and then placed in an ultraviolet ozone treatment device. (2) A hole injection layer is spin-coated on the substrate obtained in step (1); then poly(9-vinylcarbazole), abbreviated as PVK, is spin-coated on the hole injection layer to obtain a hole transport layer; (3) A red-orange light-emitting layer is spin-coated on a blank glass substrate. The red-orange light-emitting layer is a mixture of bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone(m-ACSO2) as the main body and doped with red-orange organic light-emitting guest material. Then, a polydimethylsiloxane (PDMS) with strip-shaped protrusions is used to contact the red-orange light-emitting layer material and pick it up and transfer it to the hole transport layer obtained in step (2). The shape is consistent with the shape of electrode A and covers the top of electrode A. After transfer with heating assistance, the PDMS is picked up to obtain a patterned red-orange light-emitting layer. (4) Similar to step (3), spin-coat a blue light emitting layer on a blank glass substrate, use a patternless PDMS to contact the blue light emitting layer material and pick it up and transfer it to the entire substrate obtained in step (3) to obtain a blue light emitting layer, which also has the electron transport function of the red and orange light emitting layer. (5) Based on step (4), the electron transport layer, electron injection layer and cathode are grown sequentially by thermal evaporation; thus the vertical structure of the red light region is: substrate / interdigital electrode / hole injection layer / hole transport layer / red-orange light emitting layer + blue light emitting layer / electron transport layer / electron injection layer / cathode; The vertical structure of the blue light region is: substrate / interdigital electrode / hole injection layer / hole transport layer / blue light emitting layer / electron transport layer / electron injection layer / cathode.

[0005] In step (1), the width of the interdigitated anode is between 10 micrometers and 300 micrometers, and the width of the blank area between adjacent anodes is between 10 micrometers and 300 micrometers.

[0006] Interdigitated anodes, including one or more composite structures of indium tin oxide, graphene, silver nanowires, and highly conductive polymers, are patterned into stripes by laser ablation.

[0007] The bar-shaped interdigitated anode is completely insulated from adjacent electrodes, and can be driven by the same voltage or different voltages to drive different light-emitting arrays.

[0008] In step (2), the hole injection layer is a conductive polymer, polyethylene dioxythiophene-poly(styrene sulfonate), or a modified formulation thereof, or a self-assembled molecular material containing phosphate groups.

[0009] Furthermore, the self-assembled molecular material containing phosphate groups is (4-(7H-benzo[c]carbazole-7-yl)butyl)phosphonic acid, abbreviated as 10Br-BCB-C4PA.

[0010] In step (3), the photoluminescence spectrum peak of the red-orange light-emitting layer is between 580-630 nm. The red-orange organic light-emitting guest material is one of 2-(4-diphenylamino)phenyl-10,10-dioxo-9-hydro-thioxanthion-9-one (TXO-TPA), bis(2-methyldibenzo[F,H]quinoxaline)iridium (Ir(MDQ)2acac), or bis(4-phenyl-thiophene[3,2-c]pyridine-C2,N)iridium(III) (PO-01); the doping ratio is 0.1~90 wt.%; it is prepared by template transfer printing on the hole transport layer and aligned with the corresponding bottom electrode.

[0011] Further, in step (3), the doping mass ratio of bis[3-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone(m-ACSO2) doped with bis(2-methyldibenzo[F,H]quinoxaline)iridium(Ir(MDQ)2acac) is 98.5:1.5, the solvent is chlorobenzene, the concentration of m-ACSO2 is 10 mg / mL, and the concentration of Ir(MDQ)2acac is 0.5 mg / mL.

[0012] In step (4), the photoluminescence spectrum peak of the blue light emitting layer is between 460-490 nm. The specific material is one or a mixture of bis[4-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone (DMAC-DPS), bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone (m-ACSO2), or 10-(4-((4-(9H-carbazole-9-yl)phenyl)sulfonyl)phenyl)-9,9-dimethyl-9,10-dihydroacrylidine (CzAcSF), and the mass percentage of a single material in the mixed matrix is ​​1% to 99%.

[0013] In step (5), the electron transport layer (8) is made of 1,3,5-tris(3-pyridyl-3-phenyl)benzene (TmPyPB) with a thickness of 50 nanometers; the electron injection layer (9) is made of lithium 8-hydroxyquinoline Liq with a thickness of 1 nanometer; and the cathode (10) is made of aluminum with a thickness of 100 nanometers.

[0014] The width of the strip electrode array and the spacing between the electrodes are between 10 and 300 micrometers.

[0015] In this invention, the red-orange light-emitting layer is deposited under the blue light-emitting layer. In the region where the blue and red light materials overlap, the blue light material does not emit light but acts as an electron transport layer due to the concentration of the red light layer in the exciton recombination region. In the region where there is no superposition growth of blue and red light materials, the blue light material only acts as a light-emitting layer.

[0016] The large-area color temperature adjustable light-emitting device obtained by the present invention, which is transferred and printed above horizontal interdigitated electrodes, is used for color display or lighting applications, and the color is adjustable.

[0017] The beneficial effects of this invention are as follows: (1) The white OLED of the present invention has the characteristics of simple process, large area and flexible fabrication.

[0018] (2) The white light spectrum of the present invention has good stability and the spectrum can be continuously controlled by adjusting the two anodes (electrode A and electrode B) at the bottom.

[0019] (3) The device structure described in this invention can be repeatedly stacked for manufacturing, which makes it easy to improve the stability of operation and is suitable for industrial production. Attached Figure Description

[0020] Figure 1 The figure shows the interdigitated electrode structure at the bottom of the transfer-printed white light device in Example 1; in the figure, d is the width of electrode B, and c is the distance between the edges of electrode A and electrode B. Figure 2 The figure shows the red-orange light transfer printing area of ​​Example 1. In the figure, a is the width of the interdigitated anode, b is the width of the blank area between adjacent anodes, and b > a. Figure 3 This is a cross-sectional view of the white light device in Example 1; Figure 4 The image shows the electroluminescence spectrum of the device in Example 1.

[0021] Explanation of reference numerals in the attached figures: 1-Substrate, 2-Electrode A, 3-Electrode B, 4-Hole injection layer, 5-Hole transport layer, 6-Red-orange light emitting layer, 7-Blue light emitting layer, 8-Electron transport layer, 9-Electron injection layer, 10-Cathode. Detailed Implementation

[0022] For the purpose of detailed explanation, the following specific embodiments are provided. It should be understood that these are merely illustrative examples of some of the compounds and device structures described, and do not imply the inclusion of all embodiments of the present invention, nor do they constitute a limitation on the content and scope of protection of the present invention. Unless otherwise specified, the functional materials in the embodiments can be obtained commercially or by known methods.

[0023] Example 1

[0024] (1) The electrodes on the glass substrate (1) are rapidly ablated using a laser to obtain patterned electrodes A (2) and B (3), forming interdigitated anodes, such as Figure 1 and 2As shown, the widths a and d of the two electrodes are both 100 micrometers, and the distance between their edges is c = 100 micrometers and b = 300 micrometers. Then, the electrodes are ultrasonically cleaned for 10 minutes each with acetone, ethanol, and deionized water, respectively. After that, the substrate is dried with nitrogen and then placed in an ultraviolet ozone treatment device for 10 minutes.

[0025] (2) A hole injection layer (4) is obtained by spin-coating an ethanol solution of self-assembled material (4-(7H-benzo[c]carbazole-7-yl)butyl)phosphonic acid (10Br-BCB-C4PA) at a speed of 3000 rpm on the substrate obtained in step (1) for 30 seconds. Next, a solution of poly(9-vinylcarbazole) (PVK) was spin-coated onto the hole injection layer to obtain a hole transport layer (5). The solvent was chlorobenzene with a concentration of 5 mg / mL, and the film was formed by spin-coating at a speed of 1000 rpm for 30 seconds.

[0026] A red-orange light-emitting layer is spin-coated on a blank glass substrate. The layer is bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone(m-ACSO2) doped with bis(2-methyldibenzo[F,H]quinoxaline)iridium(Ir(MDQ)2acac) at a mass ratio of 98.5:1.5. The solvent is chlorobenzene, the concentration of m-ACSO2 is 10 mg / mL, and the concentration of Ir(MDQ)2acac is 0.5 mg / mL. Then, a polydimethylsiloxane (PDMS) with strip-shaped protrusions is used to contact the red light-emitting layer material and pick it up and transfer it to the hole transport layer (5) obtained in step (2). The shape is consistent with the shape of electrode A (2) and covers the top of electrode A (2). After heat-assisted transfer printing, the PDMS is picked up and peeled off to obtain a patterned red light-emitting layer (6). (4) Similar to step (3), spin-coat a blue light-emitting layer of bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone(m-ACSO2) onto a blank glass substrate. Use a patternless PDMS to contact the blue light-emitting layer material and pick it up, then transfer it to the entire substrate obtained in step (3) (e.g., Figure 1 On the layer shown, a blue light layer (7) is obtained, which also has the electron transport function of the red light layer; (5) Based on step (4), a 50 nm electron transport layer 1,3,5-tris(3-pyridyl-3-phenyl)benzene (TmPyPB) (8), a 1 nm electron injection layer (Liq) (9), and a 100 nm cathode aluminum (10) are sequentially grown by thermal evaporation; thus, the vertical structure of the red light region is: ITO / 10Br-BCB-C4PA / PVK / m-ACSO2:Ir(MDQ)2acac(98.5:1.5) / TmPyPB / Liq / Al, while the vertical structure of the blue light region is ITO / 10Br-BCB-C4PA / PVK / m-ACSO2 / TmPyPB / Liq / Al. Figure 3 As shown, when 7 volts are applied to electrodes A (2) and B (3) of the interdigitated electrodes respectively, the following can be measured in the far field: Figure 4 The electroluminescence spectrum is shown.

[0027] The above embodiments are examples of methods and applications for constructing complementary color luminescent materials based on horizontal interdigitated electrodes and preparing white light devices. However, the scope of protection of the present invention is not limited thereto. Any simple changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a large-area color-temperature tunable light-emitting device by transfer printing above horizontal interdigitated electrodes, the light-emitting device comprising a substrate, interdigitated anodes, a hole injection layer, a hole transport layer, a red-orange light-emitting layer, a blue light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; characterized in that, The red-orange and blue-orange emitting layers are fabricated layer by layer using transfer printing to form two horizontally parallel complementary color emitting regions. White light is formed by the complementarity of sky blue and red-orange light. The specific steps are as follows: (1) The electrodes on the substrate (1) are rapidly ablated by laser to obtain patterned electrodes A (2) and B (3) to form a strip-shaped interdigitated anode. After ultrasonic cleaning with acetone, ethanol and deionized water respectively, the substrate is dried with nitrogen and then placed in an ultraviolet ozone treatment device for treatment. (2) A hole injection layer (4) is spin-coated on the substrate obtained in step (1); then poly(9-vinylcarbazole), abbreviated as PVK, is spin-coated on the hole injection layer (4) to obtain a hole transport layer (5). (3) A red-orange light-emitting layer is spin-coated on a blank glass substrate. The red-orange light-emitting layer is a mixture of bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone m-ACSO2 as the main body and doped with red-orange organic light-emitting guest material. Then, a polydimethylsiloxane PDMS with strip-shaped protrusions is used to contact the red-orange light-emitting layer material and pick it up and transfer it to the hole transport layer (5) obtained in step (2). The shape is consistent with the shape of electrode A (2) and covers the top of electrode A (2). The PDMS is released by heating to obtain a patterned red-orange light-emitting layer (6). (4) Similar to step (3), spin-coat a blue light emitting layer on a blank glass substrate, use a patternless PDMS to contact the blue light emitting layer material and pick it up and transfer it to the entire substrate obtained in step (3) to obtain a blue light emitting layer (7), which also has the electron transport function of the red and orange light emitting layer. (5) Based on step (4), the electron transport layer (8), electron injection layer (9), and cathode (10) are grown sequentially by thermal evaporation; thus, the vertical structure of the red light region is: substrate / interdigital electrode / hole injection layer / hole transport layer / red-orange light emitting layer + blue light emitting layer / electron transport layer / electron injection layer / cathode; The vertical structure of the blue light region is: substrate / interdigital electrode / hole injection layer / hole transport layer / blue light emitting layer / electron transport layer / electron injection layer / cathode.

2. The preparation method according to claim 1, characterized in that: In step (1), The width of the interdigitated anode is between 10 micrometers and 300 micrometers, and the width of the blank area between adjacent anodes is between 10 micrometers and 300 micrometers; Interdigitated anodes, including one or more composite structures of indium tin oxide, graphene, silver nanowires, and highly conductive polymers, are patterned into stripes by laser ablation; The bar-shaped interdigitated anode is completely insulated from adjacent electrodes, and can be driven by the same voltage or different voltages to drive different light-emitting arrays.

3. The preparation method according to claim 1, characterized in that: In step (2), the hole injection layer is a conductive polymer, polyethylene dioxythiophene-poly(styrene sulfonate), or a modified formulation thereof, or a self-assembled molecular material containing phosphate groups.

4. The preparation method according to claim 3, characterized in that: In step (2), the self-assembled molecular material containing phosphate groups is (4-(7H-benzo[c]carbazole-7-yl)butyl)phosphonic acid, abbreviated as 10Br-BCB-C4PA.

5. The preparation method according to claim 1, characterized in that: In step (3), the photoluminescence spectrum peak of the red-orange light-emitting layer is between 580-630 nm. The red-orange organic light-emitting guest material is one of 2-(4-diphenylamino)phenyl-10,10-dioxo-9-hydro-thioxanthion-9-one TXO-TPA, bis(2-methyldibenzo[F,H]quinoxaline)iridiumIr(MDQ)2acac, or bis(4-phenyl-thiophene[3,2-c]pyridine-C2,N)iridium(III)PO-01; the doping ratio is 0.1~90 wt.%; it is prepared by template transfer printing on the hole transport layer and aligned with the corresponding bottom electrode.

6. The preparation method according to claim 5, characterized in that: In step (3), the doping mass ratio of bis[3-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone m-ACSO2 doped with bis(2-methyldibenzo[F,H]quinoxaline)iridiumIr(MDQ)2acac is 98.5:1.5, the solvent is chlorobenzene, the concentration of m-ACSO2 is 10 mg / mL, and the concentration of Ir(MDQ)2acac is 0.5 mg / mL.

7. The preparation method according to claim 1, characterized in that: In step (4), the photoluminescence spectrum peak of the blue light emitting layer is in the range of 460-490 nm. The specific materials are bis[4-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone DMAC-DPS, bis[3-(9,9-dimethyl-9,10-dihydroacrylidine)phenyl]sulfone m-ACSO2, or 10-(4-((4-(9H-carbazole-9-yl)phenyl)sulfonyl)phenyl)-9,9-dimethyl-9,10-dihydroacrylidine CzAcSF).

8. The preparation method according to claim 1, characterized in that: In step (5), the electron transport layer (8) is made of 1,3,5-tris(3-pyridyl-3-phenyl)benzene TmPyPB with a thickness of 50 nanometers; the electron injection layer (9) is made of lithium 8-hydroxyquinoline Liq with a thickness of 1 nanometer; and the cathode (10) is made of aluminum with a thickness of 100 nanometers.

9. A large-area color temperature adjustable light-emitting device with transfer printing performed above horizontal interdigitated electrodes, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8, and the color is adjustable.

10. The use of the large-area color temperature adjustable light-emitting device with transfer printing above horizontal interdigitated electrodes as described in claim 9 for color display or illumination.

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