CN113571670A

CN113571670A - Method for preparing patterned organic light-emitting device

Info

Publication number: CN113571670A
Application number: CN202110846545.4A
Authority: CN
Inventors: 吴勇; 王斯琦
Original assignee: BOE Technology Group Co Ltd
Current assignee: BOE Technology Group Co Ltd
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2021-10-29
Anticipated expiration: 2041-07-26
Also published as: CN113571670B

Abstract

The embodiment of the present disclosure provides a method of preparing a patterned organic light emitting device, including: one or more organic functional layers are formed by stripe-patterned coating, wherein the stripe pattern has a micrometer-scale line width. The method according to the present disclosure realizes a stripe-type patterned OLED device using a simple coating process, so that a stripe pattern has a micrometer-scale line width and has good edge definition.

Description

Method for preparing patterned organic light-emitting device

Technical Field

The present disclosure relates to the field of display technologies, and in particular, to a patterning method for an organic light emitting device.

Background

Solution processing techniques have attracted considerable attention in the field of Organic Light Emitting Diode (OLED) display and illumination due to low manufacturing cost, simple process, low material loss, and high scalability for large area manufacturing. In solution process technologies, OLEDs employ various printing and coating techniques to fabricate multilayer organic thin films.

In current processes, printing processes may be preferred to form laterally and/or longitudinally patterned RGB pixels requiring high resolution, while coating processes (including spin coating, doctor blading, spraying, etc.) are suitable for uniform area coating of large-OLED common layers. The solution coating process has great advantages over the printing process because of the ease of equipment maintenance and the ability to coat a variety of process materials. However, the general coating process for manufacturing patterned devices still has significant problems.

Patterning of organic thin films is difficult in coating processes where slot die coatings enable low resolution lateral patterning of organic photovoltaics, but typically have line widths in the order of millimeters, while the definition of edges is often poor. Therefore, an additional patterning process is inevitably required after coating. Photolithography and laser etching methods are generally expensive and not suitable for continuous patterning.

Disclosure of Invention

Embodiments of the present disclosure provide a method of fabricating a patterned organic light emitting device to solve or alleviate one or more technical problems of the prior art.

As an aspect of an embodiment of the present disclosure, there is provided a method of manufacturing a patterned organic light emitting device, including: forming one or more organic functional layers by stripe-patterned coating; wherein the stripe pattern has a micrometer-scale line width.

In some possible embodiments, the stripe-patterned coating is performed by means of needle slot coating.

In some possible embodiments, the needle is not hydrophobically treated, or is hydrophobically treated accordingly, depending on the hydrophilicity or hydrophobicity of the coating solution.

In some possible embodiments, the surface contact angle of the needle shaft after the hydrophobic treatment is greater than 90 °.

In some possible embodiments, the stripe width of the stripe pattern is in a range of 50 μm to 300 μm.

In some possible embodiments, the coating gap of the stripe pattern is adjusted in a range of 3 μm to 2000 μm.

In some possible embodiments, when the width of the coated stripe is greater than 100 μm, the maximum coating speed is not more than 40 mm/s; when the width of the coated stripe is less than 100 μm, the maximum coating speed is not more than 35 mm/s.

In some possible embodiments, the needle slot coating is a two-needle coating with a coating gap of 10 μm to 2000 μm.

In some possible embodiments, the hydrophobic treatment comprises coating the needle with polytetrafluoroethylene.

In some possible embodiments, the stripe pattern is a longitudinally patterned micro pattern.

In some possible embodiments, the organic functional layer is selected from one or more of a light emitting layer, a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an electron blocking layer.

In some possible embodiments, the resolution of the fringe pattern is 1 μm.

The method for manufacturing the patterned organic light emitting device in the embodiment of the disclosure realizes a longitudinal patterning micro-patterned OLED device, wherein the stripe pattern has a micrometer-scale line width and has good edge definition.

The foregoing summary is provided for the purpose of description only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present disclosure will be readily apparent by reference to the drawings and following detailed description.

Drawings

In the drawings, like reference numerals refer to the same or similar parts or elements throughout the several views unless otherwise specified. The figures are not necessarily to scale. It is appreciated that these drawings depict only some embodiments in accordance with the disclosure and are not to be considered limiting of its scope.

FIGS. 1 and 2 are optical measurement images of the stripe-coated coatings of examples 1 and 2, respectively;

FIGS. 3 and 4 are optical measurement images of the two-needle applied coatings of example 3 and comparative example 1, respectively;

figure 5 is PEDOT in example 4: pictures of the PSS stripes;

FIG. 6 is a schematic view of the structure of a device in example 4;

figure 7 is PEDOT in example 4: pictures of the PSS stripes;

fig. 8 and 9 are light-emitting images of the stripe patterns in examples 4 and 5.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art can appreciate, the described embodiments can be modified in various different ways, without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

The present invention provides a method for preparing a patterned organic functional layer in an organic light emitting device, in particular an OLED. Specifically, the invention adopts a simple needle slot coating mode to realize longitudinal patterning micro-patterning of the organic functional layer of the OLED device. The organic functional layer is an emission layer (EML), a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), a Hole Blocking Layer (HBL), an Electron Injection Layer (EIL), an Electron Transport Layer (ETL) or an Electron Blocking Layer (EBL).

In the present invention, the thin film patterning coating is performed by needle slot coating, and it is usually determined whether the needle needs to be subjected to surface hydrophobic treatment according to the hydrophilicity and hydrophobicity of the coating solution.

If the coating solution is hydrophilic, no surface treatment of the needle is necessary. If the coating solution is hydrophobic, a surface treatment of the needle is required. In the present invention, the surface hydrophobic treatment of the needle comprises coating the surface of the needle with a hydrophobic material, preferably comprises coating the needle with polytetrafluoroethylene. After the surface hydrophobic treatment, the surface contact angle of the needle head is larger than 90 degrees. The hydrophobic treatment of the needle bar can prevent the problems of capillary flow in the transverse direction and the longitudinal direction and avoid meniscus and stripe contour oscillation at the end of the stripe pattern.

In the method of the invention, the pinhole internal diameter is typically less than 160 μm, preferably less than 120 μm, for needles used for coating. The smaller the pinhole inner diameter, the narrower its coating bar width. In the method of the present invention, the width of the coating stripe is in the range of 50 to 300. mu.m, preferably 100 to 200. mu.m, and more preferably 150. mu.m.

The choice of coating speed during film coating also affects the coating stripe width. When the width of the coating stripe is more than 100 mu m, the maximum coating speed is not more than 40 mm/s; when the width of the coating stripe is less than 100 μm, the maximum coating speed is not more than 35 mm/s. The faster the coating speed, the narrower the line width, but above the maximum speed, streak breakage may occur.

According to one embodiment, the method of the invention can also be applied by means of a two-needle coating. One of the two is a suction needle filled with a coating solvent; one is a discharge needle containing the coating solution. The coating solution is optionally added with a surfactant before coating and filtered to remove the micro-aggregated particles in the coating solution.

The coating gap using the double needle coating method can be adjusted in the range of 10 μm to 2000 μm, and the resolution can be 1 μm. Under this gap, no meniscus is formed between the suction needle and the substrate while removing the dissolved film, and the edge is well defined.

The method of the invention realizes the stripe type patterned OLED device by using the coating process, and the line width of the stripe is in a micron order. Meanwhile, the problem of edge definition is well solved through process optimization.

Various embodiments and features of the present invention are further illustrated by the following specific examples.

Example 1

A PEDOT PSS stripe layer was applied by needle slot coating with a hydrophilic needle having an inner diameter of 108 μm at a coating speed of 30 mm/s.

Example 2

The PEDOT PSS striation layer was coated by needle slot coating with a hydrophobic needle having an inner diameter of 108 μm at a coating speed of 30 mm/s. The hydrophobic treatment mode of the needle comprises the following steps: the needle is coated with polytetrafluoroethylene for hydrophobization.

Example 3

A double needle coating was carried out by needle slot coating using a hydrophilic needle having an inner diameter of 108 μm at a coating speed of 17mm/s with a PEDOT PSS striation layer.

Comparative example 1

PSS layer was coated using the same conditions as in case C) of example 1, except that a coating speed of 1mm/s was used.

Example 4

PSS layer over PET, strip PEDOT coated by needle:

1. coating polytetrafluoroethylene on the outer surface of the needle head to make the needle head hydrophobic;

2. coating the PET with PEDOT at a coating speed of 40mm/s and a coating needle with an inner diameter of 108 μm, wherein the PET is coated with the PEDOT at a 42 μm interval, and PSS strips are used as anodes;

3. then, an HIL, an HTL, an EBL, an EML, an ETL, LiF and an Al cathode are sequentially evaporated on the anode to play a role, so that the phosphorescent device with stripe luminescence is prepared.

The device structure of the organic EL element of this example is schematically shown as follows: substrate (PET)/PEDOT PSS/HIL/HTL/EBL/EML/HBL/ETL/LiF/Al as shown in FIG. 6.

Example 5

1. Coating a long-strip PEDOT (PSS) layer on a PET substrate through a discharge needle by using double-needle coating;

2. coating polytetrafluoroethylene on the outer surface of the needle head to make the needle head have hydrophobicity;

3. micropatterning was performed using a discharge needle and a suction needle each having an inner diameter of 108 μm at a discharge rate of 1 μ L/min and a coating speed of 30 mm/s;

4. the distance between the suction needle and the discharge needle is the same as the coating distance and is 20 mu m;

5. and preparing a green phosphorescent OLED with PEDOT: PSS as HIL on an ITO substrate, wherein the patterned PEDOT: PSS stripes (the remaining functional layer structure was the same as in example 4).

Characterization test:

the fringe patterns obtained according to examples 1 and 2 were optically measured, and the resulting images are shown in fig. 1 and 2, respectively. As shown in FIGS. 1 and 2, in examples 1 and 2, the hydrophilic needle and the hydrophobic needle having the same inner diameter (108 μm) were used, and at the same coating speed (30mm/s), stripe patterns having line widths of 60 μm and 54 μm were obtained, respectively, and the line edges were clearly defined.

The stripe patterns obtained by the hydrophilic-double needle coating according to example 3 and comparative example 1 were optically measured, and the obtained images are shown in fig. 3 and 4, respectively. As shown in fig. 3 and 4, the same inner diameter (108 μm) of the hydrophilic needle was used in both example 3 and comparative example 1, and the stripe patterns obtained by coating the hydrophilic needles of 17 were optically measured, and the images obtained were respectively shown in fig. 3 and 4. As shown in FIGS. 3 and 4, stripe patterns with line widths of 60 μm and gaps of 260 μm and 396 μm, respectively, were obtained at coating speeds of example mm/s and 1mm/s, respectively, and line edges were clearly defined. However, the end of the stripe pattern according to comparative example 1 has a meniscus.

The stripe pattern obtained by needle coating according to example 4 was optically measured, and the resulting image was shown in fig. 5. As shown in FIG. 5, the stripe pattern obtained in example 4 had a length of 12.7mm, a line width of the stripe of 73 to 84 μm, and a gap of 37 to 44 μm.

PEDOT prepared according to example 4: the PSS strips are illustrated in fig. 7, with the long pattern having a clear edge definition.

Luminescence images of the stripe patterns prepared according to examples 4 and 5 are shown in fig. 8 and 9, respectively. As shown in fig. 8 and 9, in examples 4 and 5, which respectively employ single hydrophobic needle coating and double hydrophobic needle coating, the stripe pattern prepared according to example 4 has a line width of 68 μm and sharp edges; the stripe pattern prepared according to example 5 had a gap of 350 μm and the edges were sharp.

The above is only a specific embodiment of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive various changes or substitutions within the technical scope of the present disclosure, which should be covered by the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A method of making a patterned organic light emitting device, comprising: forming one or more organic functional layers by stripe-patterned coating;

wherein the stripe pattern has a micrometer-scale line width.

2. The method of claim 1, wherein the stripe-patterned coating is performed by needle slot coating.

3. The method according to claim 2, wherein the needle is not hydrophobically treated or is hydrophobically treated depending on the hydrophilicity or hydrophobicity of the coating solution, respectively.

4. A method according to claim 3, wherein the surface contact angle of the needle after the hydrophobic treatment is greater than 90 °.

5. The method of claim 1, wherein the stripe pattern has a stripe width in a range of 50 μm to 300 μm.

6. The method of claim 1, wherein the stripe pattern has a coating gap in a range of 3 μ ι η to 2000 μ ι η.

7. The method according to claim 5, wherein when the width of the coated stripe is more than 100 μm, the maximum coating speed is not more than 40 mm/s; when the width of the coated stripe is less than 100 μm, the maximum coating speed is not more than 35 mm/s.

8. The method of claim 2, wherein the needle slot coating is a two-needle coating with a coating gap of 10 to 2000 μ ι η.

9. The method of claim 3, wherein the hydrophobic treatment comprises coating the needle with polytetrafluoroethylene.

10. The method of claim 3, wherein the stripe pattern is a longitudinally patterned micropattern.

11. The method of claim 1, wherein the organic light emitting device is an organic light emitting diode.

12. The method according to claim 1, wherein the organic functional layer is selected from one or more of a light-emitting layer, a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an electron blocking layer.

13. The method according to claim 6 or 8, wherein the resolution of the fringe pattern is 1 μm.