OLED display panel and OLED display device applying it

Disclosed are an OLED display panel and an OLED display device. The OLED display panel includes an array substrate (21) which is covered by a cathode (211) and a color filter substrate (22) on which an auxiliary electrode (221) is formed. A contact structure is disposed between the color filter substrate (22) and the array substrate (21) to electrically connect the cathode (211) and the auxiliary electrode (221), and the contacting area between the contact structure and the array substrate (21) is greater than or equal to that between auxiliary electrode (221) and the contact structure. The OLED display panel avoids broken circuit between the auxiliary electrode and the cathode that tends to occur due to excessive pressure upon cell-assembling a top-emitting OLED display panel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of PCT/CN2014/088076 filed on Oct. 1, 2014, which claims priority under 35 U.S.C. §119 of Chinese Application No. 201410194343.6 filed on May 9, 2014, the disclosure of which is incorporated by reference.

FIELD OF THE INVENTION

Embodiments of the present invention relate to an OLED display panel and an OLED display device applying it.

BACKGROUND

In flat display panels, organic light emitting diode (OLED) display panels have received people's attention widely due to their advantages such as self luminescence, fast response, wide viewing angle, high luminance, fresh colors and being light and thin.

The structure of an OLED usually includes an anode layer, a cathode layer and a luminescent layer disposed between the anode layer and the cathode layer. The luminescence principle of an OLED is as follows. When a voltage is applied between the anode layer and the cathode layer, under the driving of the external voltage, holes injected from the anode layer overcome the interfacial barrier and are transported into the luminescent layer, and electrons injected from the cathode layer overcome the interfacial barrier and are transported into the luminescent layer. Holes and electrons arriving in the luminescent layer recombine to form excitons that experience radiative transitions to bring about luminescence, namely electroluminescence. According to different light emitting surfaces, OLED display panels may be classified into top emitting and bottom emitting types. An OLED display panel includes a pixel array.

In order to increase light transmittance, thin transparent conducting materials are required for the cathode. However, a thin transparent cathode has a high sheet resistance, and a large voltage drop would occur when a current flows through the cathode. Therefore, the farther a pixel is from the power supply point, the smaller cathode voltage it obtains, which leads to a lower display luminance of the pixel than a pixel closer to the power supply point, thereby deteriorating the luminance uniformity of the OLED display device.

SUMMARY

At least one embodiment of the present invention provides an OLED display panel and an OLED display device applying it to avoid broken circuit between the auxiliary electrode and the cathode that tends to occur due to excessive pressure upon cell-assembling a top emitting OLED display panel.

At least one embodiment of the present invention provides an OLED display panel comprising: an array substrate which is covered by a cathode; a color filter substrate on which an auxiliary electrode is formed; and a contact structure provided between the color filter substrate and the array substrate. The contact structure is configured to electrically connect the cathode and the auxiliary electrode, and the contacting area between the contact structure and the array substrate is greater than or equal to that between the auxiliary electrode and the contact structure.

For example, in one embodiment, the contact structure comprises a spacer and a transparent conductive film on the color filter substrate, the spacer is formed on the auxiliary electrode, the transparent conductive film covers a surface of the color filter substrate and covers at least a surface of the spacer and the auxiliary electrode not blocked by the spacer; a pixel defining layer of the array substrate has a depressed section at a location corresponding to the spacer; the cathode further covers the surface in the depressed section; the spacer on the color filter substrate, whose surface is covered with the transparent conductive film, is inserted into the depressed section of the array substrate whose surface is covered with the cathode.

For example, in one embodiment, a surface shape of the depressed section after being covered by the cathode on the surface matches a surface shape of the spacer contained in the depressed section after being covered by the transparent conductive film on its surface.

For example, conducting glue is placed between the spacer, the surface of which is covered by the transparent conductive film, contained in the depressed section and the cathode in the depressed section.

For example, in one embodiment, the contact structure comprises a spacer formed on a planarization layer of the color filter substrate, and the auxiliary electrode is on top of the spacer; a pixel defining layer of the array substrate has a depressed section at a location corresponding to the spacer; the cathode further covers the surface in the depressed section; the spacer on the color filter substrate with the auxiliary electrode formed on its top is inserted into the depressed section of the array substrate whose surface is covered with the cathode.

For example, a surface shape of the depressed section of the array substrate after being covered by the cathode on the surface matches a surface shape of the spacer contained in the depressed section which is formed on the color filter substrate with the auxiliary electrode on its top.

For example, conducting glue is placed between the spacer, which has the auxiliary electrode on its top, contained in the depressed section and the cathode in the depressed section.

For example, in one embodiment, transparent conducting glue is placed in a gap between the array substrate and the color filter substrate, and the transparent conducting glue is placed at least between the auxiliary electrode and the cathode to form the contact structure.

At least one embodiment of the present invention provides an OLED display device including the above-mentioned OLED display panel.

DETAIL DESCRIPTION

FIG. 1shows a structure of a pixel in a top emitting OLED display panel, which includes an array substrate and a color filter substrate. The array substrate includes a thin film transistor device layer (not shown inFIG. 1), an anode103, a pixel defining layer104, a luminescent layer105and a cathode106formed on a first substrate101; and the color filter substrate includes a black matrix108, a color filter109and a planarization layer110formed on a second substrate107. The pixel defining layer104corresponds to the black matrix108in their locations. In operation of the OLED display panel, light is emitted from the luminescent layer105by applying a voltage between the anode103and the cathode106, and light (as shown inFIG. 1by the hollow arrowhead) transmits through the transparent cathode106and the color filter substrate on the top, realizing top emission.

The OLED display panel includes a pixel array consisting of a plurality of pixels shown inFIG. 1. Anodes103of the pixels are separated by the pixel defining layer104for mutual electrical insulation, and the anode of each pixel obtains electrical signals from the thin film transistor connected therewith. The luminescent layer105and the cathode106cover the entire pixel array, and the cathodes are supplied with power by a power supply on a side of the pixel array.

In order to solve deteriotation of the luminance uniformity, it is possible to provide an auxiliary electrode111with small resistance on the planarization layer of the color filter substrate to reduce the resistance of the cathode106, as shown inFIG. 1. A spacer112is formed on the auxiliary electrode111to prevent the substrate surface from damage caused by hard contact between the substrates while cell-assembling the color filter substrate and the array substrate. A transparent conductive layer113is further placed on the surface of the color filter substrate to realize electrical connection between the auxiliary electrode111and the cathode106after cell-assembling the color filter substrate and the array substrate.

The inventors found out that when the OLED display panel shown inFIG. 1is manufactured, the spacer112formed on the auxiliary electrode111has an elongated conical structure with a small area at the top, and while cell-assembling the color filter substrate and the array substrate, the transparency conductive layer covering the top of the spacer contacts the array substrate. Due to a small area of the top of the spacer, the contacting area is significantly smaller than the surface area of the auxiliary electrode that faces the array substrate, and a large force is exerted on the spacer112, which makes the top of the spacer112experience a large pressure, and the transparent conductive layer113on the top of the spacer112is subjected to a large pressure and tends to break, thereby causing broken circuit between the cathode and the auxiliary electrode.

At least one embodiment of the present invention provides an OLED display panel. As shown inFIG. 2, the OLED display panel includes an array substrate21which is covered by a cathode211and a color filter substrate22on which an auxiliary electrode221is formed. The OLED display panel further includes a contact structure disposed between the color filter substrate22and the array substrate21to electrically connect the cathode211and the auxiliary electrode221, and the contacting area between the contact structure and the array substrate21is greater than that between auxiliary electrodes221and the contact structure.

In the OLED display panel provided in at least one embodiment of the present invention, the contact structure can electrically connect the auxiliary electrode and the cathode, and the contacting area between the contact structure and the array substrate is larger than that between the auxiliary electrode and the contact structure, thereby increasing the contacting area between the contact structure and the cathode covering the array substrate. Even if the contact structure is subjected to a large force, the contacting region thereof experiences a small pressure, which may significantly reduce the risk of broken circuit between the auxiliary electrode and the cathode due to large pressure upon cell-assembling.

In the OLED display panel provided in the above-mentioned embodiment, as shown inFIG. 2, the contact structure may include a spacer23and a transparent conductive film24formed on the color filter substrate22, in which the spacer23is formed on the auxiliary electrode221, and the transparent conductive film24covers a surface of the color filter substrate22and covers at least a surface of the spacer23and the auxiliary electrode221not blocked by the spacer23. The pixel defining layer212of the array substrate21has a depressed section D at a location corresponding to the spacer23; and the cathode211further covers the surface inside the depressed section D. After disposing the array substrate and the color filter substrate oppositely, the spacer23covered by the transparent conductive film24on the surface is inserted into the depressed section D covered with the cathode211on its surface.

It is to be noted that, in order to make the contact structure more clear,FIG. 2shows the structures of the array substrate21, the color filter substrate22and the contact structure before cell-assembling. Therefore, inFIG. 2, the spacer23covered by the transparent conductive film24on the surface has not been inserted into the depressed section D covered by the cathode211on its surface yet. Whereas the structure of the OLED display panel described in the present embodiment is the structure after cell-assembling, as shown inFIG. 3.

The contacting region between the transparent conductive film24inside the depressed section D and the cathode211is the contacting region between the above-mentioned contact structure and the array substrate. Since the contacting region includes not only the surface of the transparent conductive layer24covering the top of the spacer23, but also includes the surface of the transparent conductive layer24covering partial side walls of the spacer23, the area of the contacting region increases significantly to be greater than the area of the contacting region between the auxiliary electrode221and the spacer23(namely contacting region between the auxiliary electrode and the contact structure). While the spacer23is exerted with a force, the pressure exerted on the transparent conductive layer24would decrease significantly, thereby reducing the risk of broken circuit between the auxiliary electrode221and the cathode211caused by break of the transparent conductive layer24.

In the OLED display panel shown inFIG. 3, a surface shape of the depressed section D after being covered by the cathode211on the surface matches for example a surface shape of the spacer23contained therein after being covered by the transparent conductive film24. This allows the transparent conductive film24and the cathode to contact closely without any gap, thereby avoiding increased contacting resistance.

In addition, in the OLED display panel shown inFIG. 2, conducting glue25may be placed between the spacer23contained in depressed section D after being covered by the transparent conductive film24on the surface and the cathode211in the depressed section D. Therefore, when any gap exists between the transparent conductive film24and the cathode211such that they can not contact closely, conducting glue25is placed in the gap to prevent contacting resistance from increasing.

In another embodiment of the present invention, as shown inFIG. 4, the contact structure may include a spacer23formed on the planarization layer222of the color filter substrate22with an auxiliary electrode221on top of the spacer23; and the pixel defining layer212of the array substrate21has a depressed section D at a location corresponding to the spacer23, and the cathode211further covers the surface inside the depressed section D. After disposing the array substrate and the color filter substrate oppositely, the spacer23with the auxiliary electrode221formed on its top is inserted into the depressed section D covered with the cathode211on the surface.

It is to be noted that, in order to make the contact structure more clear,FIG. 4shows a specific structure of the array substrate21, the color filter substrate22and the contact structure before cell-assembling. Therefore, inFIG. 4, the spacer23formed with the auxiliary electrode221on its top has not been inserted into the depressed section D covered by the cathode211on the surface yet. The structure of the OLED display panel described in the present embodiment is the structure after cell-assembling, as shown inFIG. 5.

The contacting region between the spacer23inside the depressed section D and the cathode211is the contacting region between the above-mentioned contact structure and the array substrate. Since the contacting region includes partial side wall surfaces of the spacer23, the area of contacting region is increased significantly to be greater than the area of contacting region between the auxiliary electrode221and the spacer23(namely contacting region between the auxiliary electrode and the contact structure).

In the implementations shown inFIGS. 4 and 5, since the auxiliary electrode221on top of the spacer23can electrically contact the cathode inside the depressed section D directly, it is unnecessary to provide the transparent conductive layer between the spacer23inside the depressed section D and the cathode211, which eliminates the problem of breaking of transparent conductive layer while the spacer23is exerted with a force, thereby avoiding broken circuit problem between the auxiliary electrode221and the cathode211caused by excessive pressure upon cell-assembling.

In the OLED display panel shown inFIG. 5, a surface shape of the depressed section D after being covered by the cathode211on the surface matches, for example, a surface shape of the spacer23contained therein which is formed with auxiliary electrodes221on its top. This allows the auxiliary electrode221and the spacer23contact the cathode211closely without any gap, thereby preventing the contacting resistance between the auxiliary electrode221and the cathode211from increasing.

In addition, in the OLED display panel shown inFIG. 4, conducting glue25may be placed between the spacer23with the auxiliary electrode221on its top which is contained in the depressed section D and the cathode211inside depressed sections D. Therefore, when any gap exists between the auxiliary electrode221and the cathode211such that they can not contact closely, conducting glue25is placed in the gap to prevent contacting resistance from increasing.

In yet another embodiment of the present invention, as shown inFIG. 6, transparent conducting glue25is placed in the gap between the array substrate21and the color filter substrate22, which is placed at least between the auxiliary electrode221and the cathode211to form a contact structure.

When the transparent conducting glue25is only placed between the auxiliary electrode221and the cathode211, the area of contacting region between the contact structure formed of the transparent conducting glue25and the array substrate21equals the area of contacting region between the contact structure formed of the transparent conducting glue25and the auxiliary electrode221. When the transparent conducting glue25is placed in the entire gap between the array substrate21and the color filter substrate22, the area of contacting region between the contact structure formed of the transparent conducting glue25and the array substrate21is greater than the area of contacting region between the contact structure formed of the transparent conducting glue25and the auxiliary electrode221.

In the implementation shown inFIG. 6, since the auxiliary electrode221on the color filter substrate22may electrically contact the cathode211via the transparent conducting glue25, it is not necessary to provide the transparent conductive layer between the auxiliary electrode221and the cathode211. And since the transparent conducting glue25has strong deformability, even if the transparent conducting glue25experiences a large pressure while cell-assembling, it would not be broken, thereby avoiding broken circuit problem between the auxiliary electrode221and the cathode211caused by excessive pressure upon cell-assembling.

At least one embodiment of the present invention further provides an OLED display device including the OLED display panel described in any one embodiment of the present invention. Since the probability of broken circuit between the auxiliary electrode and the cathode in the OLED display panel decreases significantly, the OLED display device may have significantly enhanced display performance.

The present application claims priority of a Chinese patent application No. 201410194343.6 filed on May 9, 2014, which is incorporated in its entirety herein by reference as part of the present application.