KR100612352B1 - Organic electro luminescent display - Google Patents

Abstract

Provided is an organic light emitting device capable of suppressing an increase in power consumption due to leakage current by providing a light blocking structure between an organic light emitting cell and a transistor, particularly a switching transistor. The organic light emitting device according to the present invention comprises a metal cathode electrode; An anode electrode insulated from the cathode electrode; An organic light emitting layer disposed between the cathode electrode and the anode electrode and constituting an organic light emitting cell together with the cathode electrode and the anode electrode; A transistor electrically connected to the anode electrode to supply a current required for driving the organic light emitting layer; A transparent semiconductor substrate on which the organic light emitting cell and the transistor are positioned; A light blocking unit is disposed on the optical path toward the transistor in the organic light emitting layer to block light flowing into the transistor.

Electroluminescence, organic light emitting cell, organic light emitting layer, cathode electrode, anode electrode, transistor, switching transistor, light blocking part

Description

Organic EL device {ORGANIC ELECTRO LUMINESCENT DISPLAY}

1 is a partial plan view of an organic light emitting diode according to a first exemplary embodiment of the present invention.

2 is a cross-sectional view taken along line II of FIG. 1.

3 is a cross-sectional view taken along the line II-II of FIG. 1.

4 is a partial plan view of an organic light emitting diode according to a second exemplary embodiment of the present invention.

5 is a cross-sectional view taken along line I′-I ′ of FIG. 4.

6 is a cross-sectional view taken along line II′-II ′ of FIG. 4.

7 is a driving circuit diagram of an organic light emitting diode according to a second exemplary embodiment of the present invention.

8 and 9 are schematic views for explaining another example of the configuration of the light blocking unit.

10 is a driving circuit diagram of an organic light emitting device according to the prior art.

The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device that can suppress an increase in power consumption due to leakage current by blocking light flowing into a transistor, particularly a switching transistor, in an organic light emitting layer.

In general, an organic light emitting diode is a self-luminous display device that emits light when an electron and a hole are paired and extinguished when charge is injected into an organic light emitting layer formed between a hole injection electrode (anode) and an electron injection electrode (cathode). According to the driving method, it is classified into a simple matrix method and an active driving method using a transistor.

Whereas the passive matrix method vertically crosses an anode line and a cathode line to selectively drive a line corresponding to a specific pixel, an active matrix method uses a transistor and an anode electrode of each organic light emitting cell. It is a drive system which connects a capacitor and maintains a voltage by capacitor capacity.

FIG. 10 is a driving circuit diagram of an organic light emitting diode according to the related art, in which an organic light emitting cell EL is connected to a driving transistor M2 to receive a current for emitting light, and a current amount of the driving transistor M2 is a switching transistor ( Controlled by the data voltage applied via M1).

At this time, the capacitor Cst is connected between the source and the gate of the driving transistor M2 to maintain the voltage supplied to the driving transistor M2 for a predetermined period, and the gate and the source of the switching transistor M1 are respectively connected to the scan line and the gate. Is connected to the data line.

Therefore, when the switching transistor M1 is turned on by the selection signal through the scan line, the driving voltage is applied to the gate of the driving transistor M2 through the data line, and the organic light emitting cell (eg, through the driving transistor M2). Electric current flows through EL) to emit light. The organic light emitting cell EL is provided for each of R, G, and B pixels to implement a color screen.

Here, the light emitted from the organic light emitting cell EL mainly travels vertically with respect to the surface of the semiconductor substrate on which the organic light emitting cell is located to reach the user, but a part of the emitted light is driven by the driving transistor M2 and the switching transistor ( Running diagonally toward M1) results in light entering these transistors.

In particular, the switching transistor M1 among the driving transistor M2 and the switching transistor M1 is strongly affected by the light even when a small amount of light is introduced therein. As a result, the leakage current of the switching transistor M1 increases due to the light introduced into the switching transistor M1, and as a result, the power consumption of the organic light emitting diode is increased.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to provide a light blocking structure between an organic light emitting cell and a transistor, in particular, a switching transistor so that light emitted from the organic light emitting cell does not flow into the switching transistor. The present invention provides an organic light emitting device capable of suppressing an increase in power consumption due to leakage current.

In order to achieve the above object, the present invention,

An organic light emitting layer comprising a metal cathode electrode, a transparent conductive material, an anode electrode insulated from the cathode electrode, and an organic light emitting layer disposed between the cathode electrode and the anode electrode and constituting an organic light emitting cell together with the cathode electrode and the anode electrode; A transistor electrically connected to the anode to supply a current required to drive the organic light emitting layer, a transparent semiconductor substrate on which the organic light emitting cell and the transistor are positioned, and a light disposed on an optical path from the organic light emitting layer toward the transistor, It provides an organic light emitting device comprising a light blocking unit for blocking.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a partial plan view of an organic light emitting diode according to a first exemplary embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of lines II and II-II shown in FIG. 1, respectively, with one driving transistor and one driving transistor. A two-transistor type for driving an organic light emitting cell using a switching transistor is illustrated.

As illustrated, the organic light emitting diode is an organic light emitting cell 8 including the cathode electrode 2, the anode electrode 4, and the organic light emitting layer 6, and a drive for supplying current to the organic light emitting cell 8. The transistor M2 and the switching transistor M1 which transfers the driving signal voltage of the data line 12 to the driving transistor M2 while being turned on / off by the selection signal by the scan line 10, and the organic light emitting cell ( The light blocking unit 14 for blocking the light flowing into the switching transistor (M1) in 8).

The cathode electrode 2 is made of a metal material, for example, aluminum, and reflects light of the organic light emitting layer 6 to the anode electrode 4, and the anode electrode 4 may transmit light of the organic light emitting layer 6. A transparent conductive material such as an indium tin oxide (ITO) film. At this time, the cathode electrode 2 and the anode electrode 4 are kept in an insulating state by the first insulating layer 16 such as acrylic.

The organic light emitting cell 8, the driving transistor M2, and the switching transistor M1 are both disposed on the transparent semiconductor substrate 18, and the semiconductor substrate 18 transmits the light of the organic light emitting layer 8 toward the user. .

As a result, when the switching transistor M1 is turned on by the selection signal of the scan line 10, the driving voltage of the data line 12 is transferred to the driving transistor M2, and a current flows in the organic light emitting layer 6. Light emission is achieved. In this process, the light blocking unit 14 blocks light flowing into the switching transistor M1 from the organic light emitting layer 6 to suppress an increase in leakage current.

That is, as shown in FIGS. 2 and 3, the light blocking unit 14 includes the passivation layer 20 and the second and third insulating layers 22 and 24 between the organic light emitting layer 6 and the switching transistor M1. Is formed in the contact hole 26 penetrating the light emitting layer, and is formed of a material that does not transmit light, for example, a metal, to block the optical path from the organic light emitting layer 6 to the switching transistor M1.

More specifically, the plurality of light blocking units 14 are continuously formed along one side of the switching transistor facing the organic light emitting layer, and the metal material, which is already used in the organic light emitting device, preferably of the switching transistor M1 It is made of a metal used as a source and a drain, for example molybdenum tungsten. In this case, the organic EL device can be easily manufactured, and the material cost can be suppressed from rising.

In particular, the light blocking portion 14 is formed at a sufficient height between the insulating polymer 28 and the passivation layer 20 to effectively block the light path from the organic light emitting layer 6 to the switching transistor M1, and moreover, the light blocking portion Since the metal material constituting (14) has good reflection efficiency, the light emitted from the organic light emitting layer 6 is reflected toward the user to increase the light utilization efficiency.

4 is a partial plan view of an organic light emitting diode according to a second exemplary embodiment of the present invention, and FIGS. 5 and 6 are cross-sectional views taken along line I'-I 'and line II'-II', respectively, shown in FIG. As shown in FIG. 7, a four-transistor type for driving an organic light emitting cell using two driving transistors and two switching transistors is illustrated.

In the present exemplary embodiment, when the gate and the source are respectively connected to the scan line (select [n]) 30 and the data line 32 and turned on by the select signal, the first switching transistor M1 receives a data signal. The first driving transistor M3 is transferred to the first driving transistor M3, and the gate and the drain side of the first driving transistor M3 are connected to perform a diode function.

The second switching transistor M2 has a gate and a drain connected to a previous scan line (select [n-1]) 34 and a node A, respectively, and according to a reset signal or a precharge voltage VI, the node A The second driving transistor M4 is connected to the node A to supply the organic light emitting cell 8 with a current proportional to the magnitude of the data signal. At this time, the capacitor C1 plays a role of maintaining the data signal of the node A for a certain period of time.

In this process, since the first and second switching transistors M1 and M2, which are particularly vulnerable to light, are positioned close to the organic light emitting cell 8, the organic light emitting cell 8 and the first and second switching transistors M1, The light blocking unit 36 is arranged between the M2s to block light from entering the first and second switching transistors M1 and M2.

That is, as shown in FIGS. 5 and 6, the light blocking unit 36 includes the passivation layer 20 and the second, between the organic light emitting cell 8 and the first and second switching transistors M1 and M2. 3 formed in the contact hole 26 penetrating the insulating layers 22 and 24 and formed of a metal material that does not transmit light, and thus, between the organic light emitting cell 8 and the first and second switching transistors M1 and M2. Block the optical path.

In addition, a plurality of light blocking units 36 are sequentially arranged along both sides of the first and second switching transistors M1 and M2 facing the organic light emitting cells 8, and the first and second switching transistors M1 and M2 are arranged in succession. Metal used as a source and a drain of, for example, molybdenum.

Meanwhile, the light blocking unit may be modified in various patterns described below in addition to the above-described embodiment. For example, as an example of the two-transistor type, as shown in FIG. 8, the light blocking unit 38 is formed in a line pattern along one side of the switching transistor M1 facing the organic light emitting cell 8, or as shown in FIG. 8. As shown in FIG. 9, the light blocking unit 40 may be formed to surround the switching transistor M1.

In addition, the configuration of the light blocking unit is not limited to the illustrated embodiment, and may be variously modified and applied according to the configuration of the organic light emitting cell and the switching transistor.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

 As described above, according to the present invention, the light blocking part is provided on the optical path toward the switching transistor in the organic light emitting layer to effectively block the light flowing into the switching transistor. Therefore, the leakage current of the switching transistor is reduced, thereby reducing the power consumption of the organic light emitting diode by the leakage current.

Claims (10)

A metal cathode electrode; An anode electrode made of a transparent conductive material and insulated from the cathode electrode; An organic light emitting layer disposed between the cathode electrode and the anode electrode and constituting an organic light emitting cell together with the cathode electrode and the anode electrode; A transistor electrically connected to the anode electrode to supply a current required for driving the organic light emitting layer; A transparent semiconductor substrate on which the organic light emitting cell and the transistor are positioned; And And a light blocking unit disposed on the light path between the organic light emitting layer and the transistor from the organic light emitting layer to the transistor to block light entering the transistor. The method of claim 1, And a switching transistor configured to transfer the driving signal voltage to the driving transistor while the transistor is turned on / off by a selection signal. The method of claim 2, The switching transistor is composed of first and second switching transistors so that the first switching transistor transfers the data signal to the second switching transistor by a selection signal, and the driving transistor is composed of first and second driving transistors to form a first driving transistor. And a second driving transistor supplying a current proportional to the magnitude of the data signal to the organic light emitting cell by the reset signal. The method of claim 2, The organic light emitting device of claim 1, wherein the light blocking unit is formed of a metal material located in a contact hole between the organic light emitting layer and the switching transistor. The method of claim 4, wherein The light blocking unit is formed of a plurality of patterns arranged spaced apart from each other along one side of the switching transistor facing the organic light emitting layer. The method of claim 4, wherein And the light blocking unit is formed of a plurality of patterns spaced apart from each other along both sides of the switching transistor facing the organic light emitting layer. The method of claim 4, wherein And the light blocking unit is formed in a line pattern between the organic light emitting layer and the switching transistor. The method of claim 4, wherein An organic light emitting device in which the light blocking unit surrounds the switching transistor. The method of claim 4, wherein The organic light emitting device of claim 1, wherein the light blocking unit is made of the same metal material as the source and the drain of the transistor. The method of claim 4, wherein The organic light emitting device of the light blocking unit is made of molybdenum tungsten.

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