Tandem OLED structure with patterned interlayers

Abstract

A tandem OLED display is provided, including a substrate backplane, an anode layer, at least two stacked OLED layers, each OLED layer comprising a plurality of pixels, at least one charge generation layer (CGL), each CGL disposed between two adjacent stacked OLED layers, and a cathode layer, wherein at least one of the CGLs is patterned, the pattern providing a gap between each of a plurality of pixels.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to pending U.S. Provisional Patent Application No. 63 / 415,888, filed October 13, 2022, entitled "Tandem OLED Structure with Patterned Intermediate Layers."

[0002] The present invention relates to tandem OLED devices, and more particularly to tandem OLED devices having patterned interlayers. [Background technology]

[0003] Organic light-emitting diode devices (OLEDs) generally comprise an anode, a cathode, and an organic electroluminescent layer sandwiched between the anode and cathode. The organic electroluminescent layer generally comprises a hole-transporting layer, an emissive layer, and an electron-transporting layer. OLEDs are attractive because of their low driving voltage, high brightness, wide viewing angle, and potential for full-color displays and other applications. Tang et al. described this multilayer OLED in their U.S. Pat. Nos. 4,769,292 and 4,885,211. OLEDs can emit different colors, such as red, green, blue, or white, depending on the emission properties of their emissive layer.

[0004] "Tandem" OLEDs are fabricated by vertically stacking multiple individual OLED units and using a single power source to drive the stack. Tandem OLED structures (sometimes called stacked OLEDs or cascade OLEDs) have been disclosed by Jones et al. in U.S. Pat. No. 6,337,492, Tanaka et al. in U.S. Pat. No. 6,107,734, Kido et al. in JP 2003 / 045676A and U.S. Pat. No. 2003 / 0189401 A1, and Liao et al. in U.S. Pat. No. 6,717,358 and U.S. Pat. No. 2003 / 0170491 A1. Tandem OLEDs have attracted widespread attention due to their superior current efficiency, brightness, and operating life compared to conventional OLEDs. In a tandem OLED, several individual electroluminescent (EL) units are electrically connected in series through a connecting stack (sometimes called a connecting electrode) that functions as a charge generation layer (CGL), where holes and electrons are generated and injected into the adjacent hole transport layer (HTL) and electron transport layer (ETL), respectively. In principle, device properties such as voltage, luminance, and current efficiency scale linearly with the number of EL units in a tandem device with an efficient CGL.

[0005] With increased current efficiency, brightness, and operational lifetime, the tandem structure is an important architecture for producing high-performance OLED devices. A key element in creating high-performance tandem OLED devices is the CGL connecting the OLED units, which plays an important role in charge generation and charge injection. High-performance CGLs have been developed in recent years and typically contain high-charge mobility (p / n-doped) materials and / or thin metal films. See, for example, U.S. Patent Nos. 8,283,054 and 7,821,201.

[0006] 1 illustrates a conventional tandem OLED subpixel 100 of the prior art, including a backplane substrate 110, an anode layer 120, a first organic emissive layer 130, an n-type doped semiconductor layer 140, a p-type doped semiconductor layer 150, a second organic emissive layer 160, and a cathode layer 170. The n-type doped semiconductor layer and the p-type doped semiconductor layer form a CGL between the first organic emissive layer 130 and the second organic emissive layer 160, respectively.

[0007] The CGL plays an essential role in tandem OLED performance and consists of a junction of n-doped and p-doped semiconductor layers for electron and hole injection, respectively. In the first stage of device operation, free electrons and holes are supplied from the CGL. In the next stage, when a bias is applied to the device, these free electrons and holes in the CGL can be transported and injected into their adjacent EL units, while electrons and holes from the cathode and anode are also injected into the EL units, respectively. After that, the bipolar current gradually reaches a steady state. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 4,769,292 [Patent Document 2] U.S. Patent No. 4,885,211 [Patent Document 3] U.S. Patent No. 6,337,492 [Patent Document 4] U.S. Patent No. 6,107,734 [Patent Document 5] Japanese Patent Application Publication No. 2003 / 045676A [Patent Document 6] U.S. Patent Application Publication No. 2003 / 0189401 A1 [Patent Document 7] U.S. Patent No. 6,717,358 [Patent Document 8] U.S. Patent Application Publication No. 2003 / 0170491 A1 [Patent Document 9] U.S. Patent No. 8,283,054 [Patent Document 10] U.S. Patent No. 7,821,201 Summary of the Invention [Problem to be solved by the invention]

[0009] In a tandem OLED display, a highly conductive CGL as a common layer is problematic due to lateral current leakage, especially when the pixel-to-pixel gap is small in a high-resolution display. Figure 2 illustrates a prior art tandem OLED display having a substrate backplane 210, an anode layer 220, an OLED-1 layer 230, a CGL 240, an OLED-2 layer 250, and a cathode layer 260. As shown in Figure 1, when pixel 1 is turned on, lateral current may leak through CGL 240 to neighboring pixels (pixel 2, pixel 3), resulting in unwanted emission from OLED-2 250, causing emission crosstalk. This is particularly serious in the case of doped transport layer materials. Preventing this lateral current leakage and emission crosstalk is highly desirable.

[0010] All references cited herein are fully incorporated by reference in their entirety. [Means for solving the problem]

[0011] It should be understood that this Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to be used to limit the scope of the claimed subject matter.

[0012] In a first exemplary embodiment of the present invention, a tandem OLED display is provided, including a substrate backplane, an anode layer, at least two stacked OLED layers, each OLED layer having a plurality of pixels, at least one charge generation layer (CGL), each CGL disposed between two adjacent stacked OLED layers, and a cathode layer, wherein at least one of the CGLs is patterned, the pattern providing a gap between each of a plurality of pixels.

[0013] The patterned CGL can be made of an organic material. Alternatively, the patterned CGL can be made of a metal. The patterned CGL may be processed in a high vacuum by thermal expansion. The patterned CGL can have at least two layers. The thickness dimension of the patterned CGL can be, for example, in the range of about 0.5 μm to 50 μm. The gap in the CGL layer can be, for example, in the range of 0.2 μm to 50 μm.

[0014] The anode layer may also be patterned with gaps between each of the plurality of pixels. Similarly, the cathode layer may also be patterned with gaps between each of the plurality of pixels. At least one of the OLED layers may also be patterned with gaps between each of the plurality of pixels.

[0015] In a second exemplary embodiment of the present invention, a tandem OLED display is provided, including a substrate backplane, an anode layer, at least two stacked OLED layers, each OLED layer comprising a plurality of pixels, at least one charge generation layer, each CGL disposed between two adjacent stacked OLED layers, and a cathode layer. At least one of the CGLs is patterned, the pattern providing gaps between each of the plurality of pixels. The anode layer is patterned with gaps between each of the plurality of pixels, the cathode layer is patterned with gaps between each of the plurality of pixels, and at least one of the OLED layers is patterned with gaps between each of the plurality of pixels.

[0016] The patterned CGL can be fabricated from an organic material. Alternatively, the patterned CGL can be fabricated from a metal. The patterned CGL may be processed in a high vacuum by thermal expansion. The patterned CGL can include at least two layers. The thickness dimension of the patterned CGL can be, for example, in the range of about 0.5 μm to 50 μm. The gap in the CGL layer can be, for example, in the range of 0.2 μm to 50 μm.

[0017] Embodiments of the present invention will be better understood with reference to the following detailed description taken in conjunction with the drawings, which are not necessarily to scale. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 depicts a conventional OLED subpixel of the prior art, including a CGL. [Figure 2] FIG. 1 is a simplified block diagram of a conventional tandem OLED display of the prior art with a typical CGL. [Figure 3] FIG. 2 is a simplified block diagram of a tandem OLED display having a patterned CGL in accordance with an exemplary embodiment of the present invention. [Figure 4]FIG. 1 is a simplified block diagram of a tandem OLED display having a patterned CGL and other layers in accordance with another exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Referring now to the drawings, wherein like reference numerals refer to like elements throughout the several views, FIG. 3 shows a tandem OLED display 10 having a patterned interlayer in accordance with an exemplary embodiment of the present invention.

[0020] Tandem OLED display 10 includes a substrate backplane 12, an anode layer 14, an OLED-1 layer 16, a CGL 18, an OLED-2 layer 20, and a cathode layer 22. According to an exemplary embodiment of the present invention, CGL 18 is patterned so that for each individual pixel, there are gaps 24, 26 between active pixels 28, 30, 32.

[0021] For example, the CGL 18 to be patterned can be an organic material or a metal. CGL 18 patterning can be performed in high vacuum, for example, by thermal evaporation, as is known. The CGL 18 to be patterned can be one layer, or more than one layer. The CGL 18 to be patterned can be, for example, 0.5 μm to 50 μm thick. The gap between the patterned CGL 18 and the adjacent layer can be, for example, 0.2 μm to 50 μm.

[0022] 4, a tandem OLED display 50 is shown including a substrate backplane 52, an anode layer 54, an OLED-1 layer 56, a CGL 58, an OLED-2 layer 60, and a cathode layer 62. In this tandem OLED display 50, the anode layer 54, the OLED-1 layer 56, and the OLED-2 layer 60 may be stacked in a similar manner to the CGL 58, with the exception of the CGL 58. This provides further protection against lateral current leakage and emission crosstalk.

[0023] The device applies to both white OLEDs with color filters and directly patterned OLEDs.

[0024] The present invention offers many advantages over the prior art. First, as noted above, a tandem OLED display 10 with a patterned CGL will significantly reduce lateral current leakage and crosstalk in the display 10. Furthermore, the display 10 of the present invention provides high resolution, high efficiency, and long operating life.

[0025] It should be understood that this disclosure teaches only one example of an exemplary embodiment, that many variations of the invention will be readily apparent to those skilled in the art after reading this disclosure, and that the scope of the invention is determined by the claims that follow. [Explanation of symbols]

[0026] 10 Tandem OLED display 12-Board Backplane 14 anode layer 16 OLED-1 layer 18 CGL 20 OLED-2 layers 22 cathode layer 24 Gap 26 Gap 28 pixels 30 pixels 32 pixels 50 Tandem OLED displays 52 PCB Backplane 54 Anode layer 56 OLED-1 layer 58 CGL 60 OLED-2 layers 62 cathode layer 100 tandem OLED subpixels 110 Backplane Board 120 anode layer 130 First organic emissive layer 140 n-type doped semiconductor layer 150 p-type doped semiconductor layer 160 Second organic emissive layer 170 cathode layer 210 Board Backplane 220 Anode layer 230 OLED-1 layer 240 CGL 250 OLED-2 layers 260 cathode layer

Claims

1. (a) a substrate backplane; (b) an anode layer; (c) at least two stacked OLED layers, each OLED layer comprising a plurality of pixels; (d) at least one charge generation layer (CGL), each CGL disposed between two adjacent stacked OLED layers; (e) a cathode layer; Equipped with (f) a tandem OLED display, wherein at least one of the CGLs is patterned, the pattern providing a gap between each of the plurality of pixels.

2. 10. The tandem OLED display of claim 1, wherein the patterned CGL is made of an organic material.

3. 10. The tandem OLED display of claim 1, wherein the patterned CGL is made of metal.

4. 10. The tandem OLED display of claim 1, wherein the patterned CGL is processed in high vacuum by thermal expansion.

5. 10. The tandem OLED display of claim 1, wherein the patterned CGL comprises at least two layers.

6. 10. The tandem OLED display of claim 1, wherein the patterned CGL has a thickness dimension ranging from about 0.5 [mu]m to 50 [mu]m.

7. 10. The tandem OLED display of claim 1, wherein the gap in the CGL layer ranges from 0.2 μm to 50 μm.

8. 10. The tandem OLED display of claim 1, wherein the anode layer is patterned with gaps between each of the plurality of pixels.

9. 10. The tandem OLED display of claim 1, wherein the cathode layer is patterned with gaps between each of the plurality of pixels.

10. 10. The tandem OLED display of claim 1, wherein at least one of said OLED layers is patterned with gaps between each of said plurality of pixels.

11. (a) a substrate backplane; (b) an anode layer; (c) at least two stacked OLED layers, each OLED layer comprising a plurality of pixels; (d) at least one charge generation layer (CGL), each CGL disposed between two adjacent stacked OLED layers; (e) a cathode layer; Equipped with (f) at least one of the CGLs is patterned, the pattern providing a gap between each of the plurality of pixels; (g) the anode layer is patterned with gaps between each of the plurality of pixels; (h) the cathode layer is patterned with gaps between each of the plurality of pixels; (i) A tandem OLED display, wherein at least one of the OLED layers is patterned with a gap between each of the plurality of pixels.

12. 12. The tandem OLED display of claim 11, wherein the patterned CGL is made of an organic material.

13. 12. The tandem OLED display of claim 11, wherein the patterned CGL is made of metal.

14. 12. The tandem OLED display of claim 11, wherein the patterned CGL is processed in high vacuum by thermal expansion.

15. 12. The tandem OLED display of claim 11, wherein the patterned CGL comprises at least two layers.

16. 12. The tandem OLED display of claim 11, wherein the patterned CGL has a thickness dimension ranging from about 0.5 μm to 50 μm.

17. 12. The tandem OLED display of claim 11, wherein the gap in the CGL layer ranges from 0.2 μm to 50 μm.

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