JP2001035662A - Organic electroluminescence element display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance driving characteristics and facilitate manufacture of a panel by installing an organic EL element formed by stacking a transparent electrode, an organic material layer for emitting light by electron or hole injection, and a metal electrode on a matrix-shaped emission part on a transparent substrate in order; and a n-type field effect transistor in which a source electrode is connected to the electron supply side and a drain electrode is connected to the metal electrode. SOLUTION: Common cathode lines 12 and data signal lines 13 in parallel to each other between which an organic EL element 200 of light emitting parts of red R, green G, and blue B of plural light emitting picture elements 111, and a capacitor 300 for constituting a switching circuit together with FETs 10, 11 are interposed are alternately installed. A scanning signal line 16 electrically separated from the lines 12, 13, perpendicularly crossing to them, and arranged together with a common anode line 15 is sequentially scanned according to an RGB signal to the data signal line 13, and the organic EL element 200 of the intersection picture elements 111 emits light. The n-type FETs 10, 11 have higher mobility than a p-type FET, and do not damage the organic material in manufacture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for an organic electroluminescence device, and more particularly, to such an organic EL material utilizing electroluminescence (hereinafter, also referred to as EL) of an organic compound material which emits light by injection of electrons and holes. The present invention relates to an organic EL element provided with a light emitting layer composed of a thin film of the above, and an organic EL element display panel in which a plurality of the switching elements are arranged in a matrix.

[0002]

2. Description of the Related Art As a display capable of achieving low power consumption, high display quality, and thinness, an organic EL element display formed by arranging a plurality of organic EL elements in a matrix has attracted attention. As shown in FIG. 1, each organic EL element 200 has an electron injection mainly composed of an organic compound on a transparent substrate 1 such as a glass plate on which a transparent electrode 201 made of indium tin oxide (ITO) is formed. Layers, electron transport layers such as electron transport layers, hole injection layers,
A hole transporting functional layer such as a hole transporting layer, at least one organic material layer 202 including a light emitting layer, and a metal electrode 2
No. 03 is laminated. A positive voltage is applied to the anode of the transparent electrode 201 and a negative voltage is applied to the cathode of the metal electrode 203,
That is, when a direct current is applied between the transparent electrode and the metal electrode, the light emitting layer in the organic material layer 202 emits light.

In an organic EL device, excitons are generated by recombination of electrons injected from a metal cathode and holes injected from a transparent anode into a light-emitting layer, and the excitons emit light in the process of deactivation. . Therefore, the organic EL element 200 can be electrically represented by an equivalent circuit as shown in FIG. As can be seen from the figure, the organic EL element has a capacitance component C
And an asymmetric conductive light-emitting diode component E coupled in parallel with the capacitance component. In the organic EL device, when a direct-current light emission drive voltage is applied between the electrodes, the charge is accumulated in the capacitance component C. When the charge exceeds the barrier voltage or the light emission threshold voltage inherent to the device, the transparent electrode (the diode component E Current starts flowing from the anode side to the organic material layer serving as the light emitting layer, and emits light at an intensity proportional to the current. The characteristic of the voltage V-current I-luminance L of such an element is similar to the characteristic of the diode. The current I is extremely small at a voltage equal to or lower than the light emission threshold Vth, and rapidly increases at a voltage equal to or higher than the light emission threshold Vth. It is an increasing characteristic. The current I and the luminance L are almost proportional. Such an organic EL element exhibits light emission luminance in proportion to a current corresponding to the drive voltage when a drive voltage exceeding the light emission threshold Vth is applied to the element, and is driven when the drive voltage applied is equal to or lower than the light emission threshold Vth. No current flows and the emission luminance remains zero.

An organic EL element display device is a light emitting device having an image display array composed of a plurality of light emitting pixels arranged in a so-called matrix arranged in intersecting rows and columns, that is, organic EL elements. . As an example of a driving method of the organic EL element display device, there is a method called a simple matrix driving method. The display device of the simple matrix drive system arranges a plurality of anode lines and cathode lines in a matrix (lattice), and connects an organic EL element at each intersection of the anode lines and the cathode lines arranged in the matrix. One of the anode line and the cathode line is sequentially selected and scanned at a predetermined time interval, and the other line is driven by a drive source in synchronization with the scanning, so that the organic E at an arbitrary intersection position is obtained.
This is to make the L element emit light. In this method, since each organic EL element is turned on only for the access time, a large current and a high voltage are required to make a large screen.

[0005]

In order to increase the size of the screen of the display device, in addition to the organic EL device display device of the simple matrix drive system, an active matrix drive system can be considered. This is because the above-described anode line and cathode line are replaced with a scanning signal line and a data signal line, and a thin film transistor (TFT: Thin Film Tran
A current is supplied to each pixel by switching using a sistor, and the organic EL element emits light. TFTs include elements made of p-Si and a-Si, metal oxide semiconductor field effect transistors, so-called MOS transistors.
−FET (Metal Oxide Semiconductor Field Effect Tr
ansistor) (hereinafter also referred to as FET).
For example, in a MOS-FET, two inversion conduction regions are formed on a semiconductor, for example, a Si substrate, and an oxide SiO ₂ thin film and a metal gate electrode are sequentially provided on the substrate surface between the inversion conduction regions. The electric field controls the conductivity of the substrate surface.

An organic EL element display panel using an N-type FET as a driving transistor is disclosed in Japanese Patent Laid-Open No. 10-16156.
3. In such a panel, a transparent electrode made of ITO is formed on the organic material layer. However, since the ITO film is formed at a high temperature, there is a disadvantage that the organic EL material is destroyed at a high temperature. Therefore, an object of the present invention is to provide an N-type F
It is an object of the present invention to provide an organic EL element display device in which an ET formed at a specific position on a common substrate is not destroyed.

[0007]

An organic electroluminescence display device according to the present invention has a display arrangement in which a plurality of light emitting portions are arranged in a matrix on a transparent substrate, and each of the light emitting portions is an organic electroluminescent element. And an organic electroluminescence display device including an N-type field effect transistor, wherein the organic electroluminescence element comprises, on the transparent substrate, at least a transparent electrode, an organic material layer emitting light by injection of electrons and holes, and a metal electrode. Are sequentially stacked, and the N-type field effect transistor has a source electrode connected to the electron supply side and a drain electrode connected to the metal electrode.

In the organic electroluminescence element display device according to the present invention, the N-type field effect transistors in the adjacent light emitting portions are adjacent to each other, and the organic electroluminescence elements are adjacent to each other. In the organic electroluminescence element display device of the present invention, the organic electroluminescence element display device is formed on the substrate and the N
An address field-effect transistor connected to a gate electrode of the field-effect transistor.

[0009] In the organic electroluminescence element display device according to the present invention, a capacitor is formed on the substrate and connected to a gate electrode of the N-type field effect transistor. In the organic electroluminescence element display device of the present invention,
An insulating film which covers the gate electrode and the source electrode of the field effect transistor and has an opening exposing the light emitting region of the transparent electrode and the drain electrode of the N type field effect transistor is provided.

[0010] In the organic electroluminescence element display device according to the present invention, the N-type field effect transistors in the adjacent light emitting portions are symmetrically arranged about a common cathode line.
In the manufacturing method of the present invention, a plurality of light-emitting portions have a display arrangement arranged in a matrix on a transparent substrate, and each of the light-emitting portions supplies electrons to the organic electroluminescence element and the organic electroluminescence element. An N-type field effect transistor for driving the organic electroluminescent element, wherein the organic electroluminescent element is formed on the transparent electrode by injecting at least one layer of electrons and / or holes formed on the transparent electrode and on the transparent electrode. An organic material layer including a light-emitting organic electroluminescent material layer and a metal electrode formed on the organic material layer, wherein the N-type field-effect transistors in the adjacent light-emitting portions are adjacent to each other and the organic electroluminescent element Method of manufacturing organic electroluminescent element display device adjacent to each other An element forming step of forming at least the N-type field-effect transistor and the transparent electrode on the transparent substrate; and covering a gate electrode and a source electrode of the N-type field-effect transistor, and a light-emitting region of the transparent electrode. Forming an insulating film having an opening exposing the drain electrode of the N-type field effect transistor; forming the organic material layer on a light emitting region of the transparent electrode; and forming the metal electrode on the organic material layer. A source electrode of the N-type field effect transistor is connected to the electron supply side, and a drain electrode thereof is connected to the metal electrode.

[0011] In the method of manufacturing an organic electroluminescence element display device, a capacitor formed on the substrate and connected to a gate electrode of the N-type field effect transistor is formed in the element forming step. In the element forming step of the method for manufacturing an organic electroluminescence element display device, an address field effect transistor formed on the substrate and connected to a gate electrode of the N-type field effect transistor is formed. .

[0012]

According to the organic electroluminescence element display device of the present invention, the mobility is superior to that of the P-type FET.
A display device having excellent driving characteristics using an N-type FET can be easily manufactured without damaging the organic material.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows a part of a display panel in an organic EL element display device according to an embodiment using an active matrix driving method. This display panel 109
On a transparent display substrate, three light-emitting portions (organic EL devices) arranged in a matrix and each of which has a red R, a green G, and a blue B
(Image display array) composed of a plurality of light-emitting pixels 111 composed of elements. Two F per light emitting part per pixel
The organic EL device 200 includes a switching circuit including the ETs 10 and 11 and the capacitor 300, and the organic EL element 200. Such a light emitting unit combination unit is integrated by the number of all pixels for each pixel, and a display-side substrate of an organic EL element display device having an image display array including a plurality of light emitting pixels arranged in a matrix is formed. ing.

A common cathode line 12 and a data signal line 13 extending in parallel with an organic EL element 200 and a capacitor 300 interposed therebetween are alternately provided on a glass display substrate of the organic EL element display device. A common anode line 15 and a scanning signal line 16 are provided, which are electrically separated and orthogonally arranged and extend. The scanning signal line 16 is sequentially scanned in accordance with the RGB signals to the data signal line 13 to selectively emit light from the organic EL element 200 at the intersection pixel.

FIG. 4 shows the embodiment shown in FIG.
2 shows a circuit configuration of one light emitting unit. FET 11 for address
Is connected to a scanning signal line 16 to which a scanning signal for scanning a row from the scanning circuit is supplied.
The source S of T11 is connected to a data signal line 13 to which a signal from a write circuit corresponding to data in the frame memory is supplied.

The drain D of the addressing FET 11 is connected to the gate G and the capacitor 300 of the driving N-type FET 10 for driving the organic EL element.
To the common cathode line 12 via The source S of the N-type FET 10 for driving the organic EL element is connected to the common cathode line 12, and the drain D of the FET 11 is connected to the metal cathode such as Al of the organic EL element 200, while the ITO anode of the organic EL element 200, It is connected to a common anode line 15 through a transparent electrode. The gate G of the FET 10 is also connected to the common cathode line 12 via the capacitor 300. The common cathode line 12 and the common anode line 15 are connected to a power supply circuit and controlled respectively.

The light emission control operation of the unit pixel of the display panel 109 in which a plurality of such circuits are arranged in rows and columns is as follows. When an ON voltage is supplied to the gate G of the FET 11 from the scanning signal line 16, the voltage of the data supplied to the source S of the FET 11 is transmitted to the drain D. When an off voltage is supplied to the gate G of the FET 11, F
ET11 is cut off, and the voltage of the data supplied to the source S is not transmitted to the drain.

Accordingly, while the gate G of the FET 11 is at the ON voltage, the voltage of the source S is charged in the capacitor 300, and the voltage is supplied to the gate G of the FET 10. F
The ET 10 becomes conductive, and a current flows from the drain D to the source S based on the gate voltage and the voltage applied from the power supply circuit to the drain D through the common anode line 15 and the organic EL element 200, and the organic EL element 200 emits light with the corresponding luminance. Let me know.

When the gate G of the FET 11 is turned off, the FET 11 is closed, the voltage of the gate G is held by the electric charge accumulated in the capacitor 300, the current is maintained for a predetermined time, and the light emission of the organic EL element 200 is performed. Is also maintained. Next, a manufacturing process of the display panel 109 of the organic EL element display device will be described. (1) An ITO electrode and various lines are formed on a transparent substrate, and an insulating film is formed thereon.

First, as shown in FIG.
A glass substrate 1 on which a transparent electrode (anode) 201 of a first display electrode formed of a matrix is formed. The scanning signal line 16 with the gate electrode 11G of the addressing FET 11 is formed between the transparent electrodes 201 using a metal having a low resistivity such as Al, and further laminated so as to overlap the edge of the ITO transparent electrode 201. A common anode line 15 made of Al, that is, a bus line is also formed. At the same time, one electrode 301 of the capacitor 300 and the gate electrode 10G of the driving FET 10 connected thereto are also formed.

An insulating layer made of a SiO ₂ insulating material having an opening for exposing the transparent electrode 201 for laminating an organic material layer including an organic electroluminescent material layer for emitting light on the substrate 1 provided with each conductive portion. 3 is formed. The insulating layer 3 functions as an oxide SiO ₂ thin film of the FETs 10 and 11 in addition to the insulating function of the wiring, and the capacitor 300
Functions as a dielectric. The insulating layer 3 has an FET 11
Contact hole CH for the drain electrode 11D is formed.

(2) TFT 11 (TFT for address)
The TFT 10 (drive FET) and the like are formed. Next, as shown in FIG. 6, the amorphous silicon layers (a-S
i) and an amorphous silicon layer (n.sup. ⁺ -a-Si) doped with an N-type impurity, and then etched using a predetermined mask to form a channel portion of each FET to form an FET region 10a, 11a is formed. Here, the drive FET 10 is an N-type, but an address FET.
11 may be N-type or P-type. Thus, the source and drain electrodes 10S, 10D, and 11D are formed at predetermined positions of the FET regions 10a and 11a on the insulating layer 3. The source electrode 10S is the FET region 1 for the adjacent FET 10.
0a to connect the drain electrode 10D to the organic EL.
It is formed so as to face the transparent electrode 201 of the element 200. The drain electrode 11D of the FET 11 is extended to the FET region 11a via a contact hole for connecting a capacitor and a drain.

Next, the FET 1 is placed on the insulating layer 3 so as to cross the common anode line 15 and the scanning signal line 16.
Data signal line 13 integrated with one source 11S
To form The source 11S is on the opposite side of the drain 11D. Similarly, a common cathode line 12 is formed on the insulating layer 3 so as to cross the common anode line 15 and the scanning signal line 16. The common cathode line 12 is integrally formed so as to be connected to the source electrode 10S of the driving FET 10 connected thereto and to be simultaneously connected to the other electrode 302 of the capacitor 300.

(3) An opening insulating film is formed, and a driving FE is formed.
Only the T drain and ITO are exposed. Thus, FE
After forming the switching circuit of the T, the capacitor and the connection line, as shown in FIGS. 7 and 8, the transparent electrode 201 and the drain of the driving FET 10 are stacked in order to stack an organic material layer including a light emitting organic electroluminescent material layer. An opening insulating layer 3a having an opening for exposing the electrode 10D is formed on the switching circuit.

(4) Each organic material layer is formed in an organic EL element region. Next, as shown in FIG. 9, a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron injection layer are sequentially formed on the anode transparent electrode 201 by mask evaporation to form an organic material layer 2.
02 is formed. The organic material layer 202 is formed on the transparent electrode 201 so as not to cover the exposed drain electrode 10D. Here, using a predetermined film forming mask in which an opening is located above the transparent electrode 201, R, G, and B light emitting organic EL media are formed into a film of a predetermined thickness in each set.

(5) A metal electrode is formed in a region including the organic EL element region and the drain region. The film forming mask for opening the transparent electrode is removed, and then, as shown in FIGS. 10 and 11, on the three types of organic material layers 202 formed,
Using a method such as mask evaporation or sputtering, Al-
A metal having a low work function such as Li is formed as the metal electrode 203 of the cathode. The metal electrode 203 is formed so as to cover the exposed drain electrode 10D and the organic material layer 202.
The thickness of the metal film may be large as long as there is no problem.

As described above, in the organic electroluminescence element display device, the ITO of the organic EL element 200 is used.
The transparent electrode (anode) 201 is commonly connected to the common anode line 15 of the bus line. Driving FET (N-type FE
T) 10 has its drain 10D connected to the metal cathode 203 of the organic EL element 200 and its source 10S arranged on the opposite side connected to the common cathode line 12.

In order to form the organic EL element 200 and to connect the drain 10D of the N-type FET 10 to the metal cathode 203 of the organic EL element 200, the drain 10D and the I
An insulating film that covers a gate and a source having an opening that exposes the TO transparent electrode 201 is provided. In the two pixels adjacent to each other in the direction in which the scanning signal line 16 extends, the arrangement of the organic EL element and the N-type FEET is symmetric about the common cathode line 12.

[0029]

As described above, according to the organic electroluminescence element display device of the present invention, the driving characteristics are excellent by using the N-type TFT, and the organic material is not damaged unlike the prior art. In addition, the panel can be easily manufactured, and a high-definition display device can be realized.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of an organic EL element in a display device.

FIG. 2 is a diagram showing an equivalent circuit of an organic EL element.

FIG. 3 is a plan view showing a part of a display panel in an organic EL element display device of an active matrix drive system according to an embodiment of the present invention, viewed from the display side.

FIG. 4 is a circuit diagram showing an FET and an organic EL element formed on a display panel of an organic EL element display device according to an example of the present invention.

FIG. 5 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL device display device according to an example of the present invention.

FIG. 6 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL element display device according to an example of the present invention.

FIG. 7 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL device display device according to an example of the present invention.

FIG. 8 is a sectional view taken along line AA in FIG. 7; FIG. 2 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL element display device according to an embodiment of the present invention.

FIG. 9 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL element display device according to an example of the present invention.

FIG. 10 is a schematic partial enlarged plan view of a substrate in a process of manufacturing a display panel of an organic EL element display device according to an example of the present invention.

FIG. 11 is a sectional view taken along line AA in FIG. 10;

[Explanation of symbols]

 Reference Signs List 1 substrate 3 insulating layer 4 organic thin film 5, 6 metal electrode 10, 11 FET S, 10S, 11S source electrode D, 10D, 11D drain electrode G, 10G, 11G gate electrode 12 cathode line 13 data signal line 15 anode line 16 scanning Signal line 109 Display panel 200 Organic EL element 300 Capacitor

Continued on the front page F term (reference) 3K007 AB18 BA06 CA01 CB01 DA00 DB03 EB00 FA01 5C094 AA14 AA43 BA03 BA27 CA19 DA09 EA05 EB02 FB01

Claims (9)

[Claims] An organic electroluminescent element display device having a display arrangement in which a plurality of light emitting units are arranged in a matrix on a transparent substrate, wherein each of the light emitting units includes an organic electroluminescent element and an N-type field effect transistor. The organic electroluminescence element comprises, on the transparent substrate, at least a transparent electrode, an organic material layer that emits light by injection of electrons and / or holes, and a metal electrode, which are sequentially laminated, and the N-type field effect An organic electroluminescence element display device, wherein the transistor has a source electrode connected to the electron supply side and a drain electrode connected to the metal electrode. 2. The organic electroluminescent element display device according to claim 1, wherein the N-type field effect transistors in the adjacent light emitting units are adjacent to each other, and the organic electroluminescent elements are adjacent to each other. 3. The organic electroluminescent element display device according to claim 1, further comprising an address field effect transistor formed on said substrate and connected to a gate electrode of said N-type field effect transistor. 4. The organic electroluminescence device display according to claim 1, further comprising a capacitor formed on the substrate and connected to a gate electrode of the N-type field effect transistor. 5. An insulating film which covers a gate electrode and a source electrode of the N-type field effect transistor and has an opening exposing a light emitting region of the transparent electrode and a drain electrode of the N-type field effect transistor. The organic electroluminescence element display device according to claim 1, wherein: 6. The organic electroluminescence element display device according to claim 1, wherein the N-type field-effect transistors in the adjacent light-emitting portions are symmetrically arranged around a common cathode line. 7. A display arrangement in which a plurality of light emitting units are arranged in a matrix on a transparent substrate, wherein each of the light emitting units supplies an electron to the organic electroluminescence element and the organic electroluminescence element, and An organic electroluminescent element including a driving N-type field effect transistor, wherein the organic electroluminescent element is formed on the transparent substrate, and is formed on the transparent electrode and emits light by injection of at least one layer of electrons and / or holes. A method for manufacturing an organic electroluminescent element display device comprising an organic material layer including an electroluminescent material layer and a metal electrode formed on the organic material layer, wherein at least the N-type field effect transistor and the transparent electrode are An element forming step of forming on a transparent substrate, and the n-type field effect transistor Forming an insulating film covering the gate electrode and the source electrode and having an opening exposing the light emitting region of the transparent electrode and the drain electrode of the N-type field effect transistor; and forming the organic material layer on the light emitting region of the transparent electrode. Forming a metal electrode on the organic material layer, a source electrode of the N-type field effect transistor is connected to an electron supply side, and a drain electrode of the N-type field effect transistor is connected to the metal electrode. A method for manufacturing an organic electroluminescence element display device, wherein the display device is connected. 8. The method according to claim 7, wherein in the element forming step, a capacitor formed on the substrate and connected to a gate electrode of the N-type field effect transistor is formed. 9. The manufacturing method according to claim 7, wherein, in the device forming step, an address field effect transistor formed on the substrate and connected to a gate electrode of the N-type field effect transistor is formed. Method.