Organic light-emitting diode display panel, organic light-emitting diode display device, and method for manufacturing an organic light-emitting diode display panel

Abstract

Organic light-emitting diode (OLED) display panel having the following features: a substrate (100; 200); a thin film transistor (TFT) (110) arranged on the substrate, the TFT having a source electrode (104) and a drain electrode (105); a power line (108; 208) arranged above the substrate; an auxiliary electrode (216; 316; 416; 516) electrically connected to the power line; a signal input terminal (218; 318; 418) electrically connected to the power line and providing an input signal; and wherein for two sections of a combination of the auxiliary electrode and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is less than a resistance value of a section close to the signal input terminal, the auxiliary electrode (216; 316; 416; 516) comprising a plurality of separate sub-auxiliary electrodes and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes.

Description

[0001] The present application relates to the field of a display, in particular to an organic light emitting diode display panel, an organic light emitting diode display device and a method for manufacturing the organic light emitting diode display panel thereof.

[0002] An organic light-emitting diode (OLED) device uses electroluminescence from organic fluorescent compounds instead of a backlight, making the OLED device small and portable. OLED devices also offer other advantages such as a wide viewing angle and fast response.

[0003] The OLED device includes a cathode, an anode, and an organic film made of an organic compound disposed between the cathode and the anode. When a voltage is applied between the cathode and the anode, holes migrate from an electrode with a positive electrical potential to an organic light-emitting layer via a hole transport layer (HTL); and electrons migrate from an electrode with a negative electrical potential to the organic light-emitting layer via an electron transport layer (ETL). Excitations are generated by recombination (recombination) of the holes and electrons, and they are stimulated to emit light, thereby providing light for the OLED device.US 2006 / 0 113 900 A1 discloses an organic display device and a method for manufacturing the same configured to prevent the IR decay of a second electrode by forming an auxiliary electrode line in an organic display device.

[0004] The object of the present invention is to provide an organic light-emitting diode display panel and a method for producing an OLED display panel.

[0005] This object is achieved by an organic light-emitting diode display panel according to claim 1 and by a method according to claim 15.

[0006] The application provides an OLED display panel. The OLED display panel comprises: a substrate; a thin-film transistor (TFT) disposed on the substrate, the TFT having a source electrode and a drain electrode; a power line disposed above the substrate; an auxiliary electrode electrically connected to the power line; and a signal input terminal electrically connected to the power line and providing an input signal. For two sections of a combination of the auxiliary electrode and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is lower than a resistance value of a section close to the signal input terminal.The auxiliary electrode has a plurality of separate sub-auxiliary electrodes, and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes.

[0007] The application further provides an OLED display device comprising the above OLED display panel.

[0008] The application further provides a method for manufacturing an OLED display panel. The method comprises: providing a substrate; forming a TFT comprising a source electrode and a drain electrode over the substrate; forming a power line; forming a first electrode over the TFT, the first electrode being electrically connected to one of the source electrode and the drain electrode; forming an auxiliary electrode, a resistance value per unit length of the auxiliary electrode varying along the auxiliary electrode, and the auxiliary electrode being electrically connected to the power line; forming an organic layer; and forming a second electrode over the organic layer. The method further comprises forming a signal input terminal electrically connected to the power line.For two sections of a combination of the auxiliary electrode and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is less than a resistance value of a section close to the signal input terminal. The auxiliary electrode has a plurality of separate sub-auxiliary electrodes, and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes.

[0009] With the application, the voltage drop along the power line is mitigated; a position experiencing a large voltage drop is provided with a large compensation, and the voltage drop along the power line is reduced; and while compensating for the voltage drop, patterns in the field are not affected, and an aperture ratio of the field is not affected.

[0010] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 is a plan view of a conventional OLED device; Fig. 2 is a sectional view of a pixel of the conventional OLED device; Fig. 3 is a sectional view of a pixel of an OLED display panel according to an embodiment of the application; Fig. 4 is a plan view of an OLED display panel according to an embodiment of the application; Fig. 5 a plan view of an OLED display panel according to an embodiment of the application. Fig. 6 is a plan view of an OLED display panel according to an embodiment of the application; Fig. 7 is a sectional view of a pixel of an OLED display panel according to an embodiment of the application; Fig. 8a to Fig. 8c simulated values ​​of resistance values ​​according to an embodiment of the application; and Fig. 9 is a schematic diagram of an OLED display device according to an embodiment of the application.

[0011] To better explain technical solutions according to embodiments of the application, clear and complete descriptions are provided below in conjunction with drawings for the embodiments. Obviously, the described embodiments do not encompass all embodiments of the application, but only a few embodiments. Any other embodiments obtained by those skilled in the art without the use of creative effort are within the scope of the application.

[0012] Fig. Figure 1 is a plan view of a conventional OLED device. The OLED device includes multiple pixels. Pixel units are defined by intersections of gate lines 101 and data lines 102, and the gate lines 101 are isolated from the data lines 102. Power lines 108 are arranged parallel to the data lines 102. Each pixel unit includes at least two thin-film transistors (TFTs). As shown in Fig. 1, the numerical symbol 110 represents a switching TFT, and the numerical symbol 120 represents a driving TFT. The switching TFT 110 receives a signal transmitted via the gate line 101 to control a switch to pass a signal transmitted via the data line 102 to the driving TFT 120. The driving TFT further controls an intensity of a current input to an OLED element via the power line 108. In general, the OLED device may further include one or more storage capacitors (in Fig. 1 not shown) to store data signals transmitted by the switching TFT 110.

[0013] Fig. 2 is a sectional view of a pixel of the conventional OLED device. A buffer layer 106 is disposed on a substrate 100. An active layer 103 is disposed on the buffer layer 106. A gate insulating layer 107 is provided over the active layer 103. A gate electrode 101 is disposed on the gate insulating layer 107, and a source electrode 104 and a drain electrode 105 are arranged on two sides of the gate electrode 101 in an insulating manner and are located on the gate insulating layer 107. The source electrode 104 and the drain electrode 105 are electrically connected to the active layer 103 via holes penetrating the gate insulating layer 107. The power line 108 is provided on the gate insulating layer 107. A passivation film 109 and a planar film 111 are disposed over the TFT. A first electrode 112 is disposed on the planar film 111, and the first electrode 112 is electrically connected to the drain electrode 105.A pixel definition layer 114 is disposed over the first electrode 112. The pixel definition layer 114 has a recessed region, and an organic layer 113 is disposed at the recessed region. In general, the organic layer 113 may include an HTL, a hole injection layer, a light-emitting layer, an ETL, and an electron injection layer. The organic layer 113 may be disposed at the recessed region of the pixel definition layer 114 or may be disposed over an entire surface of the pixel definition layer 114.

[0014] Fig. 3 is a sectional view of a pixel of an OLED display panel according to an embodiment of the application. Likewise, the OLED display panel according to the embodiment of the application includes a substrate 200, a buffer layer 206, an active layer 203, a gate electrode 201, a source electrode 204, a drain electrode 205, a gate insulating layer 207, a power line 208 disposed at a same layer as the drain electrode 205 and the source electrode 204, a passivation film 209, a planar film 211, a first electrode 212, an organic layer 213, and a pixel definition layer 214. The arrangement of the above components and electrical connections between the above components are the same as those in the conventional OLED device and can be understood from the description of the conventional OLED device.In a conventional design, a voltage drop is generated along the power line due to the resistance value of the power line, and the voltage drop is amplified at a location far from a signal input terminal. This voltage drop results in uneven brightness and a poor display effect. The OLED device provided in the application further includes an auxiliary electrode 216, and the auxiliary electrode 216 is electrically connected to the power line 208. A total resistance value of the auxiliary electrode 216 and the power line 208, which are electrically connected to each other, is reduced, thereby mitigating the voltage drop.Based on the fact that the auxiliary electrode is electrically connected to the power line and the overall resistance value is reduced, the auxiliary electrode may be formed in any of the layers or may be formed into a separate layer, or the auxiliary electrode and other components may be formed in a same layer. Optionally, the auxiliary electrode 216 and the first electrode 212 may be formed in a same layer. Optionally, the auxiliary electrode 216 and the first electrode 212 may be made of the same material and formed using the same etching process; thus, no additional process is required to form the auxiliary electrode. Optionally, the auxiliary electrode may be located above the power line, and in this case, an aperture ratio of the device may not be affected because the auxiliary electrode is located in a non-display region.

[0015] Since the voltage drop increases with increasing distance from the signal input terminal, the auxiliary electrode may be designed in a non-uniform shape to better compensate for the power line. For two sections of a combination of the auxiliary electrode and the power line, each section having a first length, the resistance value of a section far from the signal input terminal is optionally lower than the resistance value of a section close to the signal input terminal. The auxiliary electrode includes a plurality of separate sub-auxiliary electrodes, and the first length is a length greater than the sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes.In the uneven design, a section of the power line with a severe voltage drop is connected in parallel with a resistor with a low resistance value to effectively mitigate the voltage drop at that section of the power line. The voltage drop along the power line is small due to the compensation of the resistance value. The above effects can be achieved by adjusting the size, shape, or resistivity of the auxiliary electrode, or they can be achieved by adjusting the size, shape, or resistivity of the power line. Optionally, the resistance value per unit length of the auxiliary electrode decreases with the increase of the distance between the unit length of the auxiliary electrode and the signal input terminal.

[0016] Fig. 4 is a top view of an OLED display panel according to an embodiment of the application. Pixel units are defined by intersections of gate lines 201 and data lines 202, and the gate lines 201 are isolated from the data lines 202. Auxiliary electrodes 216 are parallel to the data lines 202 and are electrically connected to power lines (in Fig. 4 not shown) to cooperatively transmit an electrical signal emitted from a signal input terminal 218. The signal input terminal 218 may be an integrated circuit that transmits the electrical signal to the power lines to control a brightness of the OLED display panel. Generally, the signal input terminal 218, i.e., the integrated circuit, is electrically connected to a fabricated display panel to control display of the panel by inputting the signal. According to one embodiment, the resistance value per unit length of the combination of the auxiliary electrode and the power line gradually decreases with increasing distance between the unit length of the combination and the signal input terminal. The width per unit length of the auxiliary electrode 216 gradually increases with increasing distance between the unit length of the auxiliary electrode 216 and the signal input terminal.With this design, the resistance value per unit length of the auxiliary electrode 216 gradually decreases with the increasing distance between the unit length of the auxiliary electrode 216 and the signal input terminal. Consequently, a portion of the power line far from the signal input terminal is provided with a large compensation, effectively compensating for the voltage drop at a location far from the signal input terminal and mitigating the problem of uneven display. According to one embodiment, the first length mentioned above may be any length greater than zero and less than the total length of the auxiliary electrode. In fact, compensation for mitigating the voltage drop may alternatively be achieved by a non-uniform design of the power line.According to the application, the width of the auxiliary electrode is optionally larger than the width of the power line, and this design can more effectively reduce the voltage drop along the power line. Generally speaking, the wider the auxiliary electrode, the lower the resistance of the auxiliary electrode, and the better the compensation of the voltage drop along the power line. Therefore, the auxiliary electrode in the application can be designed as wide as possible, provided that no short circuit occurs between the auxiliary electrode and other electrodes and that the display effect is not affected.

[0017] Compared with adjusting the shape of the power line, the technical solution of the application has the following advantages. Only the first electrode is located in the same layer as the auxiliary electrode, while many components are located in the same layer as the power line. Therefore, if any adjustment is made to the shape of the power line, the components and the power line located in the same layer may interfere with each other, thereby impairing the display effect. However, in the application, adjusting the shape of the auxiliary electrode achieves resistance compensation without affecting the display effect, and the process is also easier to perform.

[0018] According to other embodiments of the application, the non-uniform design of the auxiliary electrode may also have other implementations. Fig. 5 is a plan view of an OLED display panel according to an embodiment of the application. As shown in Fig. 5, each auxiliary electrode 316 includes a plurality of separate sub-auxiliary electrodes. The farther a sub-auxiliary electrode is from a signal input terminal 318, the greater the width of the sub-auxiliary electrode. According to one embodiment, the first length mentioned above is a length greater than the sum of the length of the sub-auxiliary electrode and a distance between sub-auxiliary electrodes. In the discontinuous design and along a direction extending from the signal input terminal, for any two sections of a combination of the auxiliary electrode and the power line, each section having the first length, a resistance value of one section differs from a resistance value of the other section. Optionally, the length of each sub-auxiliary electrode is greater than a distance between two adjacent scanning lines; accordingly, an electrical signal can be transmitted more effectively.With a discontinuous arrangement, the total resistance values ​​can be uniform at locations at different distances from the signal input terminal, and the voltage drop is mitigated. Furthermore, in some display panel designs, patterns can be arranged at the locations of the auxiliary electrodes. In this case, the discontinuous arrangement may not affect the wiring on the display panel.

[0019] Fig. 6 is a plan view of an OLED display panel according to an embodiment of the application. Each auxiliary electrode 416 includes a plurality of separate sub-auxiliary electrodes. With increasing distance from a signal input terminal 418, distances between the respective sub-auxiliary electrodes gradually decrease, and widths of the sub-auxiliary electrodes may be equal to each other or may gradually increase. In the discontinuous arrangement, resistance values ​​are uniform at locations with different distances from the signal input terminal, and the voltage drop is mitigated. Furthermore, in some display panel designs, the wiring may be arranged at locations of the auxiliary electrodes. Here, in the discontinuous arrangement, the wiring on the display panel may not be affected. It should be noted that, to clarify structures of the display panel, data lines and gate lines in Fig. 5 and Fig. 6 are not shown and that with regard to detailed structures on Fig. 4 is referred to.

[0020] According to one embodiment of the application, the auxiliary electrode can be made of materials with different resistivities. In particular, the auxiliary electrode can be made of multiple material types. A portion of the auxiliary electrode far from the signal input terminal is made of a material with a low resistivity, and a portion of the auxiliary electrode close to the signal input terminal is made of a material with a high resistivity; thus, effective compensation of the power line is achieved. Alternatively, the auxiliary electrode can be made of a single material type. Optionally, different impurity concentrations are doped into the single material type with increasing distance from the signal input terminal to implement a gradually changing resistance value along the auxiliary electrode.For example, the conductivity of indium tin oxide (ITO) can be varied by doping one or more types of metallic elements such as Ta, Nd, and Sn into the ITO, and a non-uniform change in the resistivity of a host material, ITO, can be achieved by doping different concentrations of metallic elements at different portions of the auxiliary electrode. Note that the resistivity of the material may gradually decrease with increasing distance from the signal input terminal. Alternatively, the auxiliary electrode may comprise multiple segments; the resistivity remains the same in each segment, while the resistivity of each segment decreases with increasing distance between the respective segments and the signal input terminal.

[0021] Furthermore, other shapes or methods may be used to ensure that a portion far from the signal input terminal has a low resistance value. For example, a thickness may be adjusted, or a second auxiliary electrode may be further connected in parallel with the power line. The above-mentioned methods may be used in combination, and possible combinations are all within the scope of the application and are not listed here.

[0022] According to one embodiment of the application, a shielding layer 517 may be arranged on an auxiliary electrode 516 (as in Fig. 7). The shielding layer 517 may be made of an organic material that has a weak or no light reflection effect. If the auxiliary electrode 516 is made of a reflective material (e.g., metal), external light may be reflected by the auxiliary electrode 516, thereby reducing the contrast of the display panel. The shielding layer may prevent the reflection of an external backlight. To prevent the reflection, the auxiliary electrode 516 may optionally be made of a material with a weak or no light reflection effect. With this design, the auxiliary electrode 516 can compensate for the voltage drop along the power line without affecting the contrast of the display panel.

[0023] Fig. 8a to Fig. 8c illustrates simulated resistance values ​​of three different shapes of auxiliary electrodes in a 5.5-inch active matrix organic light-emitting diode (AMOLED) panel.

[0024] A sheet resistance is 0.56 Ω / square. An ordinate represents the resistance value of a wire. In an abscissa, the numerical symbol 1 represents an end of an auxiliary electrode located close to an IC (integrated circuit) terminal, the numerical symbol 2 represents an end of the auxiliary electrode far from the IC terminal, and a direction from the numerical symbol 1 to the numerical symbol 2 represents a direction away from the IC terminal. Fig. 8a, the width of the auxiliary electrode gradually decreases along the direction away from the IC terminal, and the corresponding resistance value increases from 750 Ω to 3250 Ω. Compensation is weak at a location far from the IC terminal. Since the voltage drop is large at a location far from the IC terminal, this auxiliary electrode design has no significant effect on compensating the voltage drop. Fig. 8b, the width of the auxiliary electrode remains constant along the direction away from the IC terminal, and the corresponding resistance value is maintained at approximately 3,200 Ω. The auxiliary electrode provides the same resistance compensation for an entire power line. Indeed, the voltage drop along the direction away from the IC terminal gradually increases. When compensating for the increasing voltage drop with the same resistance compensation, the voltage drop at a location far from the IC terminal may not be effectively compensated. Fig. 8c, the width of the auxiliary electrode gradually increases along the direction away from the IC terminal, and the corresponding resistance value decreases from 3250 Ω to 750 Ω. Therefore, at a location far from the IC terminal where the voltage drop is large, a compensation effect is significant. With this design, the large voltage drop at the location far from the IC terminal is effectively compensated.

[0025] With reference to Fig. 9, the application further discloses an OLED display device comprising the above OLED display panel.

[0026] The application further discloses a method for manufacturing an OLED display panel. The method comprises: providing a substrate; forming, on the substrate, a TFT comprising a source electrode and a drain electrode; forming a power line; forming a first electrode over the TFT, wherein the first electrode is electrically connected to the source electrode or the drain electrode; forming an auxiliary electrode, wherein a resistance value per unit length of the auxiliary electrode changes along the auxiliary electrode and the auxiliary electrode is electrically connected to the power line; forming an organic layer over the first electrode; and forming a second electrode over the organic layer. The method further comprises forming a signal input terminal electrically connected to the power line.For two sections of a combination of the auxiliary electrode and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is lower than a resistance value of a section close to the signal input terminal. The auxiliary electrode has a plurality of separate sub-auxiliary electrodes, and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes. Optionally, the auxiliary electrode is formed in a same layer as the first electrode. Optionally, the auxiliary electrode and the first electrode are formed in a same step.

[0027] The concept of reducing the resistance value of an electrode along the direction away from the signal input terminal as described in the application is also applicable to other aspects, for example, designing shapes of a cathode, an anode, or an auxiliary electrode thereof in an OLED device.

[0028] In the application, the auxiliary electrode can be configured as a single layer or multiple layers. The auxiliary electrode can be made of metal or ITO. Or an ITO layer can be provided over a metallic layer, for example, an Ag-ITO structure, an Al-ITO structure, or a Mo-ITO structure. The passivation film can be made of SiO2 or SiN. x The planar film can be made of an organic material such as acrylates or polyimides. The active layer can be made of polysilicon.

[0029] The terminology “parallel” mentioned in the description is not limited to completely parallel and can be extended accordingly to a case of essentially parallel.

Claims

[1] Organic light-emitting diode (OLED) display panel having the following features: a substrate (100; 200); a thin film transistor (TFT) (110) arranged on the substrate, the TFT having a source electrode (104) and a drain electrode (105); a power line (108; 208) arranged above the substrate; an auxiliary electrode (216; 316; 416; 516) electrically connected to the power line; a signal input terminal (218; 318; 418) electrically connected to the power line and providing an input signal; and wherein for two sections of a combination of the auxiliary electrode and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is less than a resistance value of a section close to the signal input terminal, the auxiliary electrode (216; 316; 416; 516) comprising a plurality of separate sub-auxiliary electrodes and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes. [2] The OLED display panel according to claim 1, wherein a resistance value per unit length of the combination of the auxiliary electrode (216; 316; 416; 516) and the power line gradually decreases with increasing distance between the unit length of the combination and the signal input terminal (218; 318; 418). [3] The OLED display panel according to claim 1 or 2, wherein the first length is any length greater than zero and less than a total length of the auxiliary electrode (216; 316; 416; 516). [4] An OLED display panel according to claim 1, wherein distances between respective adjacent sub-auxiliary electrodes of said auxiliary electrode (216; 316; 416; 516) gradually decrease along a direction extending from said signal input terminal (218; 318; 418). [5] The OLED display panel according to claim 1 or 4, wherein the OLED display panel has a plurality of pixel units and a length of the sub-auxiliary electrode is greater than or equal to a length of a pixel unit. [6] The OLED display panel according to any one of claims 1 to 5, wherein a width of the auxiliary electrode (216; 316; 416; 516) increases along a direction extending from the signal input terminal (218; 318; 418). [7] The OLED display panel according to any one of claims 1 to 6, wherein a specific resistance of a material from which the auxiliary electrode (216; 316; 416; 516) is made decreases along a direction extending from the signal input terminal (218; 318; 418). [8] The OLED display panel according to any one of claims 1 to 7, wherein a thickness of the auxiliary electrode (216; 316; 416; 516) increases along a direction extending from the signal input terminal (218; 318; 418). [9] OLED display panel according to one of claims 1 to 8, further comprising the following features: a first electrode (112; 212) disposed above the TFT (110) and electrically connected to the source electrode (104) or the drain electrode (105); an organic layer disposed over the substrate; and a second electrode disposed above the substrate. [10] An OLED display panel according to claim 9, wherein the auxiliary electrode (216; 316; 416; 516) is located in a same layer as the first electrode (112; 212). [11] An OLED display panel according to any one of claims 1 to 10, wherein the auxiliary electrode (216; 316; 416; 516) and the first electrode (112; 212) are made of a same material. [12] An OLED display panel according to any one of claims 1 to 10, wherein the auxiliary electrode (216; 316; 416; 516) is arranged above the power line. [13] An OLED display panel according to any one of claims 1 to 12, wherein the auxiliary electrode (216; 316; 416; 516) is covered by a layer of an opaque material or the auxiliary electrode is made of an opaque material. [14] An OLED display device comprising the OLED display panel according to any one of claims 1 to 13. [15] A method for manufacturing an OLED display panel, the method comprising the following steps: Providing a substrate; Forming, over the substrate, a TFT (110) having a source electrode (104) and a drain electrode (105); Forming a network line; Forming a first electrode (112; 212) over the TFT, the first electrode being electrically connected to the source electrode or the drain electrode; Forming an auxiliary electrode (216; 316; 416; 516), wherein a resistance value per unit length of the auxiliary electrode changes along the auxiliary electrode and the auxiliary electrode is electrically connected to the power line; Forming an organic layer over the first electrode; and Forming a second electrode over the organic layer, the method further comprising forming a signal input terminal (218; 318; 418) electrically connected to the power line, and wherein for two sections of a combination of the auxiliary electrode (216; 316; 416; 516) and the power line, each section having a first length, a resistance value of a section far from the signal input terminal is lower than a resistance value of a section close to the signal input terminal; wherein the auxiliary electrode (216; 316; 416; 516) comprises a plurality of separate sub-auxiliary electrodes, and the first length is a length greater than a sum of a length of the sub-auxiliary electrode and a distance between adjacent sub-auxiliary electrodes. [16] The method according to claim 15, wherein the auxiliary electrode (216; 316; 416; 516) is formed in a same layer as the first electrode (112; 212). [17] A method according to any one of claims 15 or 16, wherein the auxiliary electrode (216; 316; 416; 516) and the first electrode (112; 212) are formed in a same step.

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