Organic light emitting display device

Abstract

Discussed is an organic light emitting display device capable of realizing enhancement of a blue color property by using a hole-only device (HOD) structure to design a blue sub-pixel in a sub-pixel, while having the same size of sub-pixels. The blue sub-pixel can include two blue light emitting material layers stacked to form the HOD structure. The blue sub-pixel can be driven using two data lines and two driving transistors, such that the two blue light emitting material layers emit light alternately based on a frame.

Description

Technical Field

[0001] This invention relates to an organic light-emitting display device using a hole-only device (HOD) structure. Background Technology

[0002] In our information-related society, various technologies are being developed in connection with display devices used to display visual information in the form of images or pictures.

[0003] Among various display devices, organic light-emitting display devices are touted as the next generation of displays because they use organic light-emitting diodes (OLEDs). OLEDs are self-emissive elements configured to emit light from their light-emitting material layers through the recombination of electrons and holes. As a result, organic light-emitting display devices can not only possess characteristics such as fast response time, high brightness, low driving voltage, and ultra-thinness, but can also be realized in various shapes.

[0004] However, when the unit pixel of such an organic light-emitting display device is composed of red sub-pixels of an OLED configured to emit red, green sub-pixels of an OLED configured to emit green, and blue sub-pixels of an OLED configured to emit blue, the peak brightness may be limited.

[0005] Furthermore, blue OLEDs exhibit relatively low efficiency and a relatively short lifespan. Therefore, blue subpixels are designed to have a relatively large size to enhance blue properties. Summary of the Invention

[0006] Therefore, this disclosure relates to an organic light-emitting display device that substantially eliminates one or more problems caused by the limitations and disadvantages of related technologies.

[0007] One object of the present invention is to provide an organic light-emitting display device that, by using a hole-only device (HOD) structure to design blue sub-pixels, can achieve enhanced blue characteristics while having sub-pixels of the same size.

[0008] Further advantages, objects, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art upon examination of the description, or may be learned by practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, the claims, and the drawings.

[0009] To achieve these and other advantages, and according to the purposes of the invention, as embodied and broadly described herein, an organic light-emitting display device includes an organic light-emitting display device comprising a display panel including multiple data lines and multiple scan lines intersecting each other, and unit pixels arranged in a matrix such that each of the unit pixels is disposed in a region where one scan line intersects with four data lines. Each of the unit pixels comprises at least three sub-pixels, and one of the at least three sub-pixels comprising two light-emitting material layers stacked to form a hole-only device (HOD) structure.

[0010] A subpixel can be driven by two driving transistors.

[0011] A subpixel can be driven by two data lines.

[0012] A sub-pixel also includes a first electrode and a second electrode, and the first hole injection layer, the first hole transport layer, the first layer of the light-emitting material layer, the first electron transport layer, the charge generation layer, the second electron transport layer, the second layer of the light-emitting material layer, the second hole transport layer and the second hole injection layer can be stacked sequentially between the first electrode and the second electrode in this order.

[0013] The first hole injection layer, the first hole transport layer, the first luminescent material layer, the first electron transport layer, the charge generation layer, the second electron transport layer, the second luminescent material layer, the second hole transport layer, and the second hole injection layer can be formed by inkjet printing.

[0014] Each of the first and second luminescent material layers may include a blue luminescent material layer.

[0015] When a positive (+) voltage is applied to the first electrode and a negative (-) voltage is applied to the second electrode, only the first luminescent material layer emits light. When a negative (-) voltage is applied to the first electrode and a positive (+) voltage is applied to the second electrode, only the second luminescent material layer emits light.

[0016] A sub-pixel can be driven by a scan line and first and second data lines. The sub-pixel may include: a first switching transistor comprising a gate connected to the scan line, a first electrode connected to the first data line, and a second electrode connected to a first node, controlled by a scan pulse of the scan line to send a data voltage from the first data line to the first node; a first driving transistor comprising a gate connected to the first node, a first electrode connected to a first high-level voltage supply line, and a second electrode connected to the second node, thereby controlling the current flowing through a first organic light-emitting element according to the voltage of the first node; a first capacitor connected between the first node and the second node to store the data voltage supplied to the first node within a frame; a second switching transistor comprising a gate connected to the scan line, a first electrode connected to the second data line, and a second electrode connected to a third node, thereby controlled by a scan pulse of the scan line to transmit the data voltage from the second data line to the third node; a second driving transistor comprising a gate connected to the third node, a first electrode connected to a second high-level voltage supply line, and a second electrode connected to the second node, thereby controlling the current flowing through a second organic light-emitting element according to the voltage of the third node; and a second capacitor connected between the third node and the second high-level voltage supply line, which supplies the data voltage to the third node within a frame. The first and second organic light-emitting elements are connected in reverse to each other between the second node and the low-level voltage supply line.

[0017] Data voltage can be applied alternately to the first and second data lines based on frames.

[0018] The first high-level voltage supply line can apply a positive (+) high-level voltage, while the second high-level voltage supply line can apply a negative (-) high-level voltage.

[0019] Each of the first and second organic light-emitting elements may include a blue light-emitting diode.

[0020] In an organic light-emitting display device having the above-described features according to an exemplary embodiment of the present invention, the following effects are achieved.

[0021] First, the blue sub-pixel is formed with a HOD structure, wherein the first blue luminescent material layer and the second blue luminescent material layer are symmetrical about the charge generation layer and are driven by two driving transistors, such that one of the first blue luminescent material layer and the second blue luminescent material layer emits light according to the polarity of the voltage applied to the first electrode and the second electrode.

[0022] Therefore, the first and second blue light-emitting elements of the blue sub-pixel can be driven alternately based on frames, which can double the lifetime of the blue sub-pixel.

[0023] Second, even when the blue subpixel has the same size as the red or green subpixel, the blue light emission characteristics can be enhanced. Attached Figure Description

[0024] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0025] Figure 1 An organic light-emitting display device according to an exemplary embodiment of the present invention is shown;

[0026] Figure 2 This is a view of the structure of a red or green OLED of an organic light-emitting display device according to an exemplary embodiment of the present invention, and a method for manufacturing the layers of the structure according to an exemplary embodiment of the present invention;

[0027] Figure 3 This is a view of the structure of a blue OLED of an organic light-emitting display device according to an exemplary embodiment of the present invention, and a method for manufacturing the layers of the structure according to an exemplary embodiment of the present invention;

[0028] Figures 4A to 4D This is a cross-sectional view of a process for manufacturing an OLED for each sub-pixel according to an exemplary embodiment of the present invention;

[0029] Figure 5 This is an explanation Figure 3 Energy level diagram illustrating the working principle of the HOD structure;

[0030] Figure 6 This is a circuit diagram of the circuit configuration of a unit pixel of an organic light-emitting display panel according to an exemplary embodiment of the present invention;

[0031] Figure 7 This is a layout diagram of the structure of a unit pixel of an organic light-emitting display device according to an exemplary embodiment of the present invention; and

[0032] Figure 8 It is along Figure 7 The cross-sectional view taken from line I-I' in the diagram. Detailed Implementation

[0033] In the following description, a pixel circuit having the above-described features according to an exemplary embodiment of the present invention and an organic light-emitting display device including the pixel circuit will be described in detail with reference to the accompanying drawings. Throughout the specification, the same reference numerals denote substantially the same constituent elements.

[0034] Although the device described below will be illustrated with examples of devices including n-type thin-film transistors (TFTs), the device can be implemented as a p-type TFT or a TFT having both n-type and p-type characteristics. A TFT can be a three-electrode element comprising a gate, a source, and a drain. The source is the electrode configured to supply charge carriers to the transistor. Charge carriers in the TFT first flow out from the source. The drain is the electrode from which carriers discharge from the TFT to the outside of the TFT. That is, charge carriers in the TFT flow from the source to the drain.

[0035] In the case of an n-type TFT, the source voltage is lower than the drain voltage, allowing electrons to flow from the source to the drain, since electrons are charge carriers. In an n-type TFT, because electrons flow from the source to the drain, current flows from the drain to the source. Conversely, in the case of a p-type TFT, the source voltage is higher than the drain voltage, allowing holes to flow from the source to the drain, since holes are charge carriers. In a p-type TFT, current flows from the source to the drain, because holes flow from the source to the drain. However, in TFTs, the source and drain can be interchanged depending on the voltage applied to them. Considering these conditions, one of the source and drain can be called the "first electrode," and the other can be called the "second electrode." Furthermore, the terms "invention" and "disclosure" are used interchangeably.

[0036] Figure 1 An organic light-emitting display device according to an exemplary embodiment of the present invention is illustrated. All components of each organic light-emitting display device according to all embodiments of the present disclosure are operatively coupled and configured.

[0037] Reference Figure 1 An organic light-emitting display device according to an exemplary embodiment of the present invention includes: a display panel 100 having one or more pixels (or unit pixels) PXL; a data driving circuit 300 configured to drive data lines 114; a gating driving circuit 400 configured to drive scan lines 115; and a timing controller 200 configured to control the driving timing of the data driving circuit 300 and the gating driving circuit 400. The organic light-emitting display device according to an exemplary embodiment of the present invention may further include additional structures or elements.

[0038] Each subpixel of the display panel 100 includes an organic light-emitting diode (hereinafter referred to as "OLED") and pixel circuitry configured to independently drive the OLED.

[0039] Multiple data lines 114 and multiple scan lines 115 intersect each other at the display panel 100. Unit pixels PXL are arranged in a matrix, such that each unit pixel PXL is located in the area where one scan line 115 intersects with four data lines 114. Unit pixels PXL located on the same horizontal line form a pixel row. Unit pixels PXL located in a pixel row are connected to one scan line 115, and one scan line 115 may include one or more scan lines and one or more light-emitting lines.

[0040] That is, each unit pixel PXL can be connected to four data lines 114, one or more scan lines, and one or more light-emitting lines. The unit pixels PXL can collectively receive a high-level drive voltage VDD and a low-level drive voltage VSS from the power supply. Details of the configuration of this implementation will be described later.

[0041] The TFT constituting a single pixel PXL can be implemented as an oxide TFT including an oxide semiconductor layer. Considering all electron mobility, process variations, etc., oxide TFTs are advantageous in terms of expanding the display panel 100. Of course, exemplary embodiments of the present invention are not limited to the above conditions, and the semiconductor layer of the TFT can be formed of amorphous silicon, polycrystalline silicon, etc., and can include a semiconductor layer that may include materials or compounds other than oxides.

[0042] Each unit pixel PXL can consist of several subpixels, such as three subpixels, and each subpixel can include a red subpixel, a green subpixel, and a blue subpixel, such as a red OLED, a green OLED, and a blue OLED, although other colors can also be used.

[0043] One of the three sub-pixels constituting a unit pixel PXL can be designed as a blue sub-pixel with a hole-only device (HOD) structure. However, this is not required, and red or green sub-pixels can also have an HOD structure. Details of the configuration of the implementation will be described later.

[0044] The timing controller 200 can rearrange the digital video data (RGB) input from the external display panel 100 according to the resolution of the display panel 100, and can provide the rearranged digital video data (RGB) to the data drive circuit 300. Furthermore, the timing controller 200 can generate a data control signal DDC for controlling the operating timing of the data drive circuit 300 and a gating control signal GDC for controlling the operating timing of the gating drive circuit 400 based on timing signals such as the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the dot clock signal DCLK, and the data enable signal DE. Other signals or electrical signals such as ELVDD, ELVSS, and Vinit can be generated or used.

[0045] The data drive circuit 300 converts the digital video data RGB input from the timing controller 200 into analog data voltage based on the data control signal DDC.

[0046] The gating drive circuit 400 can generate scan signals and light emission signals based on the gating control signal GDC. The gating drive circuit 400 may include a scan driver and a light emission driver. The scan driver can generate scan signals in a row-sequential manner to drive one or more scan lines connected to each pixel row and can provide scan signals to the scan lines. The light emission driver can generate light emission signals in a row-sequential manner to drive one or more light emission lines connected to each pixel row and can provide light emission signals to the light emission lines.

[0047] The gating drive circuit 400 described above can be directly formed as an on-board gating driver (GIP) or included in the display panel 100.

[0048] Figure 2 This is a view of the structure of a red or green OLED of an organic light-emitting display device according to an exemplary embodiment of the present invention, and a method for manufacturing the layers of the structure according to an exemplary embodiment of the present invention.

[0049] like Figure 2 As shown, the OLED disposed at each red and green sub-pixel is configured as a hole injection layer (HIL) 11, a hole transport layer (HTL) 12, a light-emitting material layer (EML) 13 and an electron transport layer (ETL) 14, which are stacked in this order between the first electrode 10 (e.g., anode) and the second electrode 20 (e.g., cathode).

[0050] In the case of red sub-pixels, the light-emitting material layer (EML) 13 is formed of red light-emitting material, while in the case of green sub-pixels, the light-emitting material layer (EML) 13 is formed of green light-emitting material.

[0051] Hole injection layer (HIL) 11, hole transport layer (HTL) 12, light-emitting material layer (EML) 13, and electron transport layer (ETL) 14 can all be formed by inkjet printing. The second electrode 20 can be formed by deposition. Simultaneously, other layer formation processes can be used to form each of layers 11, 12, 13, and 14, as well as the second electrode 20.

[0052] Figure 3 This is a view of the structure of a blue OLED of an organic light-emitting display device according to an exemplary embodiment of the present invention, and a method for manufacturing the layers of the structure according to an exemplary embodiment of the present invention.

[0053] like Figure 3As shown, the OLED disposed at the blue sub-pixel may include a first hole injection layer (HIL) 11, a first hole transport layer (HTL) 12, a first light-emitting material layer (EML) 13, a first electron transport layer (ETL) 14, a charge generation layer (CGL) 15, a second electron transport layer (ETL) 16, a second light-emitting material layer (EML) 17, a second hole transport layer (HTL) 18, and a second hole injection layer (HIL) 19. These layers are sequentially stacked between a first electrode 10 (e.g., anode) and a second electrode 20 (e.g., cathode).

[0054] Both the first luminescent material layer 13 and the second luminescent material layer 17 are formed of blue luminescent material.

[0055] The first electrode 10 may include an ITO / Ag / ITO structure, and the second electrode 20 may include Ag.

[0056] The first hole injection layer (HIL) 11, the first hole transport layer (HTL) 12, the first light-emitting material layer (EML) 13, the first electron transport layer (ETL) 14, the charge generation layer (CGL) 15, the second electron transport layer (ETL) 16, the second light-emitting material layer (EML) 17, the second hole transport layer (HTL) 18, and the second hole injection layer (HIL) 19 can all be formed by inkjet printing. The second electrode 20 can be formed by deposition. In an embodiment of the present invention, the first light-emitting material layer (EML) 13 may be included in the first organic light-emitting element, and the second light-emitting material layer (EML) 17 may be included in the second organic light-emitting element.

[0057] This section will briefly describe a method for forming red, green, and blue subpixels in an OLED using an inkjet printing process.

[0058] Figures 4A to 4D This is a cross-sectional view of a process for manufacturing an OLED for each sub-pixel according to an exemplary embodiment of the present invention.

[0059] like Figure 4A As shown, first electrodes 10 are formed in the red, green, and blue sub-pixel regions R, G, and B, respectively, on a substrate 30 including red, green, and blue sub-pixel regions R, G, and B. The first electrodes 10 can be formed of a transparent conductive material such as ITO or IZO. Compounds other than oxides can be used.

[0060] Furthermore, a dam layer 40 with a grid pattern can be formed in the boundary portion of the sub-pixel regions R, G and B, such that the dam layer 40 overlaps with the edge portion of the first electrode 10. This is achieved by coating a hydrophobic material on the substrate 30 on which the first electrode 10 is formed and selectively removing the hydrophobic material.

[0061] The embankment layer 40 can be formed of organic or inorganic materials.

[0062] like Figure 4B As shown, for example, a hole injection material solution is dropped onto the first electrode 10, which comprises a red sub-pixel region R, a green sub-pixel region G, and a blue sub-pixel region B, using an inkjet printing process. A drying process is then performed, thereby forming a hole injection layer (HIL) 11 on the first electrode 10.

[0063] The hole injection layer (HIL) 11 can be formed from a conductive polymer (PEDOT: PSS) having an aromatic structure including thiophene, sulfonate, etc., or an aromatic amine material including alkyl, alkoxy, etc. Alternatively, the hole injection layer (HIL) 11 can include other materials or can be formed using other materials.

[0064] When the cavitation injection material solution drips, the cavitation injection layer 11 does not need to be formed on the upper surface of the embankment layer 40 because the embankment layer 40 is hydrophobic.

[0065] The solvent in the hole injection material solution evaporates through a drying process, thus retaining only the solute in the hole injection material solution.

[0066] A hole transport material solution is dropped onto the hole injection layer 11 in the red sub-pixel region R, the green sub-pixel region G, and the blue sub-pixel region B, and then dried to form a hole transport layer (HTL) 12 on the hole injection layer (HIL) 11.

[0067] The hole transport layer 12 can be formed of an amine material containing an aromatic ring, such as carbazole, naphthalene, fluorene, etc. For example, the hole transport layer 12 can be formed of materials such as 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP), N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPD), tris(4-carbazolyl-9-ylphenyl)amine (TCTA). Meanwhile, the hole transport layer (HTL) 12 can include other materials or can be formed using other materials.

[0068] Red luminescent material solution, green luminescent material solution, and blue luminescent material solution are dropped into red sub-pixel region R, green sub-pixel region G, and blue sub-pixel region B, respectively.

[0069] Then, the dripping red luminescent material solution, the dripping green luminescent material solution, and the dripping blue luminescent material solution are dried.

[0070] Therefore, the red light-emitting material layer 13R, the green light-emitting material layer 13G, and the blue light-emitting material layer 13B are formed on the hole transport layer (HTL) 12 in the red sub-pixel region R, the green sub-pixel region G, and the blue sub-pixel region B, respectively.

[0071] The red-emitting material layer 13R can be formed from materials having aromatic structures including carbazole, fluorene, imidazole, naphthalene, etc. Other materials can also be used.

[0072] The green luminescent material layer 13G can be formed from materials having aromatic structures including carbazole, fluorene, etc. Other materials can also be used.

[0073] The blue luminescent material layer 13B can be formed from a material having an aromatic structure including stilbene arylene, anthracene, pyrene, etc. Other materials can also be used.

[0074] like Figure 4C As shown, an electron transport material solution is dropped into the red sub-pixel region R, the green sub-pixel region G, and the blue sub-pixel region B, where luminescent material layers 13R, 13G, and 13B are respectively formed, and then dried to form an electron transport layer (ETL) 14 on each luminescent material layer 13R, 13G, and 13B.

[0075] The electron transport layer (ETL) 14 can be formed from materials with aromatic structures, including pyridine, triazine, diazole, triazole, etc. For example, the electron transport layer (ETL) 14 can be formed from 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]benzene (OXD), phenanthrene-2-phenanthroline (Bphen), etc. Other materials can be used.

[0076] like Figure 4D As shown, the charge generation layer (CGL) 15, the second electron transport layer (ETL) 16, the second light-emitting material layer (EML) 17, the second hole transport layer (HTL) 18, and the second hole injection layer (HIL) 19 can be formed sequentially in the blue sub-pixel region B of the red sub-pixel region R, the green sub-pixel region G, and the blue sub-pixel region B by performing the process of dripping and drying the required material solution as described above.

[0077] In addition, a second electrode 20 can be formed using a deposition process to extend along the upper part of the embankment layer 40, the electron transport layer (ETL) 14, and the second hole injection layer (HIL) 19.

[0078] The charge generation layer (CGL) 15 can be formed from a conductive polymer (PEDOT: PSS) having an aromatic structure including thiophene, sulfonate, etc., or an aromatic amine material including alkyl, alkoxy, etc. Other materials can be used.

[0079] Meanwhile, the two blue OLEDs formed in the blue sub-pixel region B can be configured with an HOD structure.

[0080] The working principle of the two blue OLEDs will be described below.

[0081] Figure 5 This is an explanation Figure 3 Energy level diagram illustrating the working principle of the HOD structure.

[0082] like Figure 3 and Figure 5 As shown, the two blue OLEDs are configured to have a structure in which the first blue luminescent material layer 13 and the second blue luminescent material layer 17 are symmetrical to each other with respect to the charge generation layer (CGL) 15.

[0083] Therefore, when a positive (+) voltage is applied to the first electrode 10 and a negative (-) voltage (forward bias) is applied to the second electrode 20, holes and electrons are generated at the interface between the charge generation layer (CGL) 15 and the first electron transport layer (ETL) 14, and at the interface between the charge generation layer (CGL) 15 and its adjacent second electron transport layer (ETL) 16. Holes and electrons are generated at the interfaces between the charge generation layer (CGL) 15 and the first electron transport layer (ETL) 14, and at the interfaces between the charge generation layer (CGL) 15 and its adjacent second electron transport layer (ETL) 16, through forward bias drift caused by the applied voltage.

[0084] Holes transferred from the first electrode 10 move to the first blue luminescent material layer (EML) 13, and electrons generated at the interface between the charge generation layer (CGL) 15 and the first electron transport layer (ETL) 14, and at the interface between the charge generation layer (CGL) 15 and its adjacent second electron transport layer (ETL) 16, can also move to the first blue luminescent material layer (EML) 13, thereby forming excitons. As a result, the first blue luminescent material layer (EML) 13 produces visible light.

[0085] In this situation, electrons transferred from the second electrode 20 cannot move to the second blue luminescent material layer (EML) 17 because the potential barriers of the second hole transport layer (HTL) 18 and the second hole injection layer (HIL) 19 are high. As a result, the second blue luminescent material layer (EML) 17 cannot emit light.

[0086] Conversely, when a negative (-) voltage is applied to the first electrode 10 and a positive (+) voltage (reverse bias) is applied to the second electrode 20, holes and electrons are generated at the interface between the charge generation layer (CGL) 15 and each of the adjacent first electron transport layer (ETL) 14 and second electron transport layer (ETL) 16.

[0087] Holes and electrons are generated at the interface between the charge generation layer (CGL) 15 and the adjacent first electron transport layer (ETL) 14, and at the interface between the charge generation layer (CGL) 15 and the adjacent second electron transport layer (ETL) 16, due to the reverse bias drift of the applied voltage.

[0088] Holes transferred from the second electrode 20 move to the second blue luminescent material layer (EML) 17, and electrons generated at the interface between the charge generation layer (CGL) 15 and the adjacent first electron transport layer (ETL) 14, and at the interface between the charge generation layer (CGL) 15 and the adjacent second electron transport layer (ETL) 16, can also move to the second blue luminescent material layer (EML) 17, thereby forming excitons. As a result, the second blue luminescent material layer (EML) 17 produces visible light.

[0089] In this situation, electrons transferred from the first electrode 10 cannot move to the first blue light-emitting material layer (EML) 13 because the potential barriers of the first hole transport layer (HTL) 11 and the first hole injection layer (HIL) 12 are high. As a result, the first blue light-emitting material layer (EML) 13 cannot emit light.

[0090] Since the above structure uses only hole current in principle, it is called a "hole-only device (HOD)" structure.

[0091] Based on the above principles, such as Figure 3 As shown, when a forward bias is applied to a blue OLED having the above-mentioned HOD structure, the first blue light-emitting material layer 13 of the HOD structure emits light, while when a reverse bias is applied to the blue OLED, the second blue light-emitting material layer 17 of the HOD structure emits light.

[0092] According to an exemplary embodiment of the present invention, the light emission characteristics of an organic light-emitting display device using the above-described structure can be enhanced.

[0093] Figure 6 This is a circuit diagram of the circuit configuration of a unit pixel of an organic light-emitting display panel according to an exemplary embodiment of the present invention.

[0094] According to an exemplary embodiment of the present invention, a unit pixel is shown to be composed of a red OLED (R), a green OLED (G), a first blue OLED (B-1), and a second blue OLED (B-2).

[0095] The first blue OLED (B-1) and the second blue OLED (B-2) are shown to be connected in opposite directions to each other, wherein the first light-emitting material layer 13 and the second light-emitting material layer 17 are configured to be symmetrical about each other with respect to the charge generation layer (CGL) 15.

[0096] like Figure 6 As shown, each pixel is driven by one scan line SCAN and four data lines DATA1, DATA2, DATA3 and DATA4.

[0097] The red and green sub-pixels are each driven by a single data line, specifically one of the corresponding data lines DATA1 and DATA2. The blue sub-pixel is driven by two data lines (DATA3 and DATA4) and two high-level voltage supply lines, VDD and -VDD. In embodiments of this invention, the voltages provided by the two high-level voltage supply lines VDD and -VDD can be the same, but this is not necessary. The high-level voltage supply line VDD can have a higher voltage level than the high-level voltage supply line -VDD, and vice versa.

[0098] Next, the configuration of pixel circuitry configured to selectively drive OLEDs, including OLED(R), OLED(G), OLED(B-1), and OLED(B-2) configured as described above, will be described.

[0099] The driving circuits configured to drive unit pixels of red OLED(R), green OLED(G), first blue OLED(B-1), and second blue OLED(B-2) respectively include first switching transistors SW1 to fourth switching transistors SW4, first driving transistors DR1 to fourth driving transistors DR4, and first capacitors C1 to fourth capacitors C4, as follows: Figure 6 As shown. In other embodiments of the invention, the colors associated with the first luminescent material layer 13 and the second luminescent material layer 17 are not limited to blue, but may also include red and green. Meanwhile, in Figure 6 In this embodiment, although a first blue OLED (B-1) and a second blue OLED (B-2) are provided for the blue OLED, in other embodiments, the first luminescent material layer 13 and the second luminescent material layer 17 can be different colors from each other, so that the sub-pixels can emit multiple different colors individually. That is, the first luminescent material layer 13 and the second luminescent material layer 17 can emit different colors, but at different times.

[0100] In the case of the first switching transistor SW1, its gate is connected to the scan line SCAN, its first electrode is connected to the first data line DATA1, and its second electrode is connected to node N1, and is therefore controlled by the scan pulse of the scan line SCAN to transmit the data voltage of the first data line DATA1 to node N1.

[0101] In the case of the second switching transistor SW2, its gate is connected to the scan line SCAN, its first electrode is connected to the second data line DATA2, and its second electrode is connected to node N2, and is therefore controlled by the scan pulse of the scan line SCAN to transmit the data voltage of the second data line DATA2 to node N2.

[0102] In the case of the third switching transistor SW3, its gate is connected to the scan line SCAN, its first electrode is connected to the third data line DATA3, and its second electrode is connected to node N3, and is therefore controlled by the scan pulse of the scan line SCAN to transmit the data voltage of the third data line DATA3 to node N3.

[0103] In the case of the fourth switching transistor SW4, its gate is connected to the scan line SCAN, its first electrode is connected to the fourth data line DATA4, and its second electrode is connected to node N4, and is therefore controlled by the scan pulse of the scan line SCAN to transmit the data voltage of the fourth data line DATA4 to node N4.

[0104] In the case of the first driving transistor DR1, its gate is connected to node N1, its first electrode is connected to the high-level voltage supply line VDD, and its second electrode is connected to node S1. Thus, the current flowing through the red OLED(R) is controlled according to the voltage of node N1.

[0105] In the case of the second driving transistor DR2, its gate is connected to node N2, its first electrode is connected to the high-level voltage supply line VDD, and its second electrode is connected to node S2. Thus, the current flowing through the green OLED (G) is controlled according to the voltage of node N2.

[0106] In the case of the third driving transistor DR3, its gate is connected to node N3, its first electrode is connected to the high-level voltage supply line VDD, and its second electrode is connected to node S3. Thus, the current flowing through the blue OLED (B-1) is controlled according to the voltage of node N3.

[0107] In the case of the fourth driving transistor DR4, its gate is connected to node N4, its first electrode is connected to the high-level voltage supply line -VDD, and its second electrode is connected to node S3. Thus, the current flowing through the blue OLED OLED (B-2) is controlled according to the voltage of node N4.

[0108] The first capacitor C1 is connected between node N1 and node S1, and thus stores the data voltage provided to node N1 within a frame.

[0109] The second capacitor C2 is connected between node N2 and node S2, and thus stores the data voltage provided to node N2 within a frame.

[0110] The third capacitor C3 is connected between node N3 and node S3, and thus stores the data voltage provided to node N3 within a frame.

[0111] The fourth capacitor C4 is connected between node N4 and the high-level voltage supply line -VDD, and thus stores the data voltage supplied to node N4 within a frame.

[0112] In this configuration, the red OLED (R) is connected between node S1 and the low-level voltage supply line VSS, and the green OLED (G) is connected between node S2 and the low-level voltage supply line VSS.

[0113] The first blue OLED (B-1) and the second blue OLED (B-2), which are connected in reverse to each other, are connected between node S3 and the low-level voltage supply line VSS.

[0114] In addition, the data voltage can be applied alternately to the third data line DATA3 and the fourth data line DATA4 based on the frame.

[0115] In the following text, details of the structure of a unit pixel having the circuit configuration described above according to an exemplary embodiment of the present invention will be described.

[0116] Figure 7 This is a layout diagram of the structure of a unit pixel of an organic light-emitting display device according to an exemplary embodiment of the present invention. Figure 8 It is along Figure 7 The cross-sectional view taken from line I-I' in the diagram.

[0117] like Figure 7 and Figure 8 As shown, a unit pixel is driven by one scan line SCAN and four data lines DATA1, DATA2, DATA3 and DATA4, and the blue sub-pixel of the unit pixel is driven by two data lines, namely data lines DATA3 and DATA4, and two high-level voltage supply lines VDD and -VDD.

[0118] The red sub-pixel is driven by a switching transistor SW1 and a driving transistor DR1, the green sub-pixel is driven by a switching transistor SW2 and a driving transistor DR2, and the blue sub-pixel is driven by two switching transistors SW3 and SW4 and two driving transistors DR3 and DR4.

[0119] like Figure 8 As shown, in a unit pixel, the first to fourth active layers A1, A2, A3 and A4 are independently formed on the substrate 30, and the gate insulating layer 31 is formed on the entire surface of the substrate 30 including the first to fourth active layers A1, A2, A3 and A4.

[0120] The first to fourth gates G1, G2, G3 and G4 are independently formed on the gate insulating layer 31, overlapping with the first to fourth active layers A1, A2, A3 and A4, respectively. An interlayer insulating layer 32 is formed on the gate insulating layer 31 including the first to fourth gates G1, G2, G3 and G4.

[0121] Multiple contact holes are formed in the gate insulating layer 31 and the interlayer insulating layer 32 to expose the two ends of the first to fourth active layers A1, A2, A3 and A4. The first source / drain S1 / D1, the second source / drain S2 / D2, the third source / drain S3 / D3 and the fourth source / drain S4 / D4 are formed on the interlayer insulating layer 32 at the two ends of the first to fourth active layers A1, A2, A3 and A4, respectively, so that the source / drain corresponding to each active layer is electrically interconnected.

[0122] In this configuration, gate G1, active layer A1, source S1, and drain D1 constitute... Figure 6 and Figure 7 The first driving transistor DR1 is shown.

[0123] Gate G2, active layer A2, source S2 and drain D2 constitute Figure 6 and Figure 7 The second driving transistor DR2 is shown.

[0124] Gate G3, active layer A3, source S3 and drain D3 constitute Figure 6 and Figure 7 The third driving transistor DR3 is shown.

[0125] Gate G4, active layer A4, source S4 and drain D4 constitute Figure 6 and Figure 7 The fourth driving transistor DR4 is shown.

[0126] A planarization layer 33 is formed on the interlayer insulating layer 32 comprising a first source / drain S1 / D1, a second source / drain S2 / D2, a third source / drain S3 / D3, and a fourth source / drain S4 / D4. First to fourth contact holes are formed at the planarization layer 33 to expose the first to fourth drains D1, D2, D3, and D4. Three first electrodes 10-1, 10-2, and 10-3 are formed in the red, green, and blue light-emitting regions, respectively, to be electrically connected to the first to fourth drains D1, D2, D3, and D4 via the first to fourth contact holes. The first electrode 10-3 is electrically connected to the third drain D3 and the fourth drain D4 via the third and fourth contact holes.

[0127] A dam layer 34 is formed in the boundary portion of each light-emitting region to overlap with the edge portions of the three first electrodes 10-1, 10-2 and 10-3, and a red light-emitting material layer 35, a green light-emitting material layer 36 and a blue light-emitting material layer 37 are formed on the three first electrodes 10-1, 10-2 and 10-3, respectively.

[0128] The red luminescent material layer 35 and the green luminescent material layer 36 are formed to have the following properties: Figure 2 The structure shown is such that the blue luminescent material layer 37 is formed having the following characteristics: Figure 3 The structure shown.

[0129] exist Figure 8 In this configuration, the source S1 of the first driving transistor DR1 and the source S2 of the second driving transistor DR2 can be electrically connected to the high-level voltage supply line VDD, such as... Figure 6 and Figure 7 As shown.

[0130] The source S3 of the third driving transistor DR3 can be electrically connected to the high-level voltage supply line VDD, and the source S4 of the fourth driving transistor DR4 can be electrically connected to the high-level voltage supply line -VDD.

[0131] In the following, the operation of a unit pixel of an organic light-emitting display device configured as described above according to an exemplary embodiment of the present invention will be described.

[0132] exist Figure 6 In the unit pixel circuit, when a scan pulse is provided to the scan line SCAN and data signals are provided to the first to third data lines DATA1, DATA2 and DATA3, during the first frame, the red OLED OLED(R) of the red sub-pixel, the green OLED OLED(G) of the green sub-pixel and the first blue OLED OLED(B-1) of the blue sub-pixel emit light, thereby displaying an image.

[0133] When a scan pulse is provided to the scan line SCAN, and data signals are provided to the first data line DATA1, the second data line DATA2, and the fourth data line DATA4, during the second frame, the red OLED (R) of the red subpixel, the green OLED (G) of the green subpixel, and the second blue OLED (B-2) of the blue subpixel emit light, thereby displaying an image.

[0134] Because the first blue OLED (B-1) and the second blue OLED (B-2) of the blue subpixel are driven alternately on a frame-based basis, the lifetime of the blue subpixel can be doubled.

[0135] In the above-described organic light-emitting display device according to an exemplary embodiment of the present invention, the blue sub-pixel is formed to have an HOD structure, wherein the first blue light-emitting material layer 13 and the second blue light-emitting material layer 17 are symmetrical about each other with respect to the charge generation layer (CGL) 15 and are driven by two driving transistors, such that one of the first blue light-emitting material layer 13 and the second blue light-emitting material layer 17 emits light according to the polarity of the voltage applied to the first electrode 10 and the second electrode 20.

[0136] Therefore, by alternately driving the first blue OLED (B-1) and the second blue OLED (B-2) of the blue sub-pixels based on frames, the lifespan of the blue sub-pixels can be doubled.

[0137] Furthermore, even when the blue subpixel has the same size as the red or green subpixel, the blue emission characteristics can be enhanced.

[0138] The foregoing description and accompanying drawings are provided to illustrate the technical concept of the invention. Those skilled in the art will understand that various modifications and variations are possible by combining, dividing, substituting, or changing the constituent elements without altering the essential characteristics of the invention. Therefore, the foregoing embodiments disclosed herein should be interpreted as merely illustrative and not as limiting the principles and scope of the invention. It should be understood that the scope of the invention is defined by the appended claims, and all equivalents thereof fall within the scope of the invention.

[0139] Cross-references to related applications

[0140] This application claims priority to Korean Patent Application No. 10-2021-0193176, filed in Korea on December 30, 2021, the entire contents of which are expressly incorporated herein by reference.

Claims

1. An organic light-emitting display device, the organic light-emitting display device comprising: The display panel includes multiple intersecting data lines and multiple scan lines, as well as unit pixels arranged in a matrix, such that each of the unit pixels is located in the area where one scan line of the display panel intersects with four data lines. A data driving circuit, configured to drive the plurality of data lines; and A gating drive circuit, configured to drive the plurality of scan lines; Each of the unit pixels comprises at least three sub-pixels. In each of the unit pixels, one of the at least three sub-pixels includes two light-emitting material layers, which are stacked to form a hole-only device (HOD) structure. The sub-pixel further includes two electron transport layers, which are interposed between the first and second luminescent material layers.

2. The organic light-emitting display device according to claim 1, wherein, Each sub-pixel is driven by two driving transistors.

3. The organic light-emitting display device according to claim 1, wherein, Each sub-pixel is driven by two data lines.

4. The organic light-emitting display device according to claim 1, wherein, The sub-pixel also includes a first electrode and a second electrode. The first hole injection layer, the first hole transport layer, the first light-emitting material layer of the two light-emitting material layers, the first electron transport layer of the two electron transport layers, the charge generation layer, the second electron transport layer of the two electron transport layers, the second light-emitting material layer of the two light-emitting material layers, the second hole transport layer and the second hole injection layer are stacked sequentially between the first electrode and the second electrode.

5. The organic light-emitting display device according to claim 4, wherein, Each of the first luminescent material layer and the second luminescent material layer includes a blue luminescent material layer.

6. The organic light-emitting display device according to claim 5, wherein, The blue luminescent material layer comprises a material having an aromatic structure, wherein the aromatic structure comprises at least one of stilbene aryl, anthracene, and pyrene.

7. The organic light-emitting display device according to claim 4, wherein, When a positive voltage is applied to the first electrode and a negative voltage is applied to the second electrode, only the first luminescent material layer emits light; and When the negative voltage is applied to the first electrode and the positive voltage is applied to the second electrode, only the second luminescent material layer emits light.

8. The organic light-emitting display device according to claim 4, wherein, The first hole injection layer, the first hole transport layer, the first light-emitting material layer, the first electron transport layer, the charge generation layer, the second electron transport layer, the second light-emitting material layer, the second hole transport layer, and the second hole injection layer are formed by inkjet printing.

9. The organic light-emitting display device according to claim 4, wherein, The first hole injection layer and the second hole injection layer comprise a conductive polymer having an aromatic structure comprising at least one of thiophene and sulfonate, or an aromatic amine-based material comprising at least one of alkyl and alkoxy.

10. The organic light-emitting display device according to claim 4, wherein, The first hole transport layer and the second hole transport layer comprise an amino group material having an aromatic ring, wherein the aromatic ring comprises at least one of carbazole, naphthalene, and fluorene.

11. The organic light-emitting display device according to claim 4, wherein, The first electron transport layer and the second electron transport layer comprise a material having an aromatic structure, wherein the aromatic structure comprises at least one of pyridine, triazine, diazole and triazole.

12. The organic light-emitting display device according to claim 4, wherein, The charge-generating layer comprises a conductive polymer having an aromatic structure or an aromatic amine-based material, wherein the aromatic structure comprises at least one of thiophene and sulfonate, and the aromatic amine-based material comprises at least one of alkyl and alkoxy groups.

13. The organic light-emitting display device according to claim 1, wherein, The sub-pixel is driven by one of the multiple scan lines and the first and second data lines of the multiple data lines; The sub-pixel includes: A first switching transistor includes a gate connected to the scan line, a first electrode connected to the first data line, and a second electrode connected to the first node. The first switching transistor is controlled by a scan pulse of the scan line to transmit the data voltage of the first data line to the first node. A first driving transistor includes a gate connected to the first node, a first electrode connected to a first high-level voltage supply line, and a second electrode connected to the second node. The first driving transistor controls the current flowing through the first organic light-emitting element according to the voltage of the first node. The first organic light-emitting element includes a first light-emitting material layer of the two light-emitting material layers. A first capacitor is connected between the first node and the second node and stores the data voltage supplied to the first node within one frame; The second switching transistor includes a gate connected to the scan line, a first electrode connected to the second data line, and a second electrode connected to the third node. The second switching transistor is controlled by the scan pulse of the scan line to transmit the data voltage of the second data line to the third node. A second driving transistor, comprising a gate connected to the third node, a first electrode connected to a second high-level voltage supply line, and a second electrode connected to the second node, wherein the second driving transistor controls the current flowing through a second organic light-emitting element according to the voltage of the third node, the second organic light-emitting element comprising a second light-emitting material layer of the two light-emitting material layers; and A second capacitor is connected between the third node and the second high-level voltage supply line, and stores the data voltage supplied to the third node within one frame; and The first organic light-emitting element and the second organic light-emitting element are connected in reverse to each other between the second node and the low-level voltage supply line.

14. The organic light-emitting display device according to claim 13, wherein, The data driving circuit alternately applies data voltage to the first data line and the second data line based on frames.

15. The organic light-emitting display device according to claim 13, wherein, The first high-level voltage supply line applies a positive high-level voltage, and the second high-level voltage supply line supplies a negative high-level voltage.

16. The organic light-emitting display device according to claim 13, wherein, Each of the first organic light-emitting element and the second organic light-emitting element includes a blue light-emitting diode.

17. The organic light-emitting display device according to claim 1, wherein, The two light-emitting material layers of a sub-pixel are stacked symmetrically with respect to the charge-generating layer interposed between the two light-emitting material layers.

18. The organic light-emitting display device according to claim 17, wherein, The one sub-pixel is a blue sub-pixel, and the remaining two sub-pixels of the at least three sub-pixels are a red sub-pixel and a green sub-pixel. The blue sub-pixel has the same size as the red sub-pixel or the green sub-pixel.

19. An organic light-emitting display device, the organic light-emitting display device comprising: The display panel includes multiple unit pixels arranged in a matrix configuration. Each of the plurality of unit pixels comprises at least three sub-pixels. Wherein, one of the at least three sub-pixels includes a first luminescent material layer and a second luminescent material layer stacked on top of each other, and each of the first luminescent material layer and the second luminescent material layer is configured to emit light of a color. in, When the first luminescent material layer is emitting light, the second luminescent material layer is not emitting light, and When the second luminescent material layer is emitting light, the first luminescent material layer is not emitting light, and Each sub-pixel further includes two electron transport layers, which are interposed between the first luminescent material layer and the second luminescent material layer.

20. The organic light-emitting display device according to claim 19, wherein the organic light-emitting display device comprises: Multiple data lines and multiple scan lines intersect each other, wherein each unit pixel is located in the area where one scan line and four data lines intersect on the display panel; A data driving circuit, configured to drive the plurality of data lines; and The selection drive circuit is configured to drive the multiple scan lines. Two of the four data lines are connected to one of the at least three sub-pixels.

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