KR100769432B1 - Organic light emitting device and method of manufacturing the same - Google Patents

Abstract

An organic light emitting device and a manufacturing method thereof are provided to reduce a size of a display device by decreasing a size of a photodiode. An organic light emitting device includes a substrate(100), a transistor, an OLED(Organic Light Emitting Diode), a photodiode, and a reflective film(110). The transistor is formed on the substrate and includes a gate, a source, and a drain. The OLED is connected to the transistor and includes a first electrode(180), an organic film(210), and a second electrode(220). The photodiode generates an electrical signal according to incident light. The reflective film is formed under the photodiode and reflects the incident light toward the photodiode. A brightness of the light emitted from the OLED is varied according to the electrical signal from the photodiode.

Description

Organic light emitting device and method of manufacturing the same

1 is a cross-sectional view illustrating a conventional organic light emitting display device.

2 is a cross-sectional view for explaining an organic light emitting display device according to the present invention.

3A to 3F are cross-sectional views illustrating a method of manufacturing an organic light emitting display device according to the present invention.

<Explanation of symbols for main parts of the drawings>

10, 100: substrate 11, 120: buffer layer

12, 130a, 130b: semiconductor layers 12a, 134: source region

12b, 135: drain region 12c, 136: channel region

13 and 140: gate insulating film 14 and 150: gate electrode

15, 160: interlayer insulating film 16a, 170a: source electrode

16b, 170b: drain electrode 17, 180: planarization film

18, 190: anode electrode 19, 200: pixel defining film

20, 210: organic thin film layer 21, 220: cathode electrode

110: reflective film 131: P junction

132: N junction 133: intrinsic semiconductor

The present invention relates to an organic electroluminescent device and a method of manufacturing the same, and more particularly, to an organic electroluminescent device having a photodiode and a method of manufacturing the same.

Organic light emitting devices are next-generation display devices with self-luminous characteristics.They are organic light emitting devices that have a viewing angle, contrast, response speed, and power consumption compared to liquid crystal display devices (LCDs). Has excellent properties.

The organic light emitting diode includes an organic light emitting diode composed of an anode electrode, an organic thin film layer, and a cathode electrode, and the organic light emitting diode is connected in a matrix manner between a scan line and a signal line. A passive matrix method constituting a pixel and an active matrix method controlled by a thin film transistor (TFT), in which an operation of each pixel serves as a switch, may be configured.

1 is a schematic cross-sectional view for describing a conventional organic light emitting display device including a thin film transistor.

A buffer layer 11 is formed on the substrate 10, and a semiconductor layer 12 providing source and drain regions 12a and 12b and a channel region 12c is formed on the buffer layer 11. The gate electrode 14 insulated from the semiconductor layer 12 by the gate insulating layer 13 is formed on the semiconductor layer 12, and the source and drain regions 12a and An interlayer insulating film 15 in which contact holes are formed to expose 12b) is formed. Source and drain electrodes 16a and 16b connected to the source and drain regions 12a and 12b are formed on the interlayer insulating layer 15, and the entire upper surface including the source and drain electrodes 16a and 16b. A planarization film 17 having via holes formed therein is formed to expose the source or drain electrodes 16a or 16b. On the planarization layer 17, the pixel defining layer 19 for exposing a predetermined portion of the anode electrode 18 to define an anode electrode 18 and a light emitting region connected to the source or drain electrode 16a or 16b through a via hole. ) Is formed, and the organic thin film layer 20 and the cathode electrode 21 are formed on the anode electrode 18.

As described above, in the organic light emitting display device including the anode electrode 18, the organic thin film layer 20, and the cathode electrode 21, when a predetermined voltage is applied to the anode electrode 18 and the cathode electrode 21, the anode electrode 18 is provided. Holes injected through) and electrons injected through the cathode electrode 21 are recombined in the organic thin film layer 20, and emit light by the energy difference generated in this process.

However, the organic light emitting device configured as described above has a problem in that the brightness of light emitted by deterioration of film quality and light emission characteristics is deteriorated with time because the organic thin film layer 20 that emits light is made of an organic material. In addition, while the emitted light is emitted to the outside, light is incident on the organic light emitting device from an external light source, and there is a problem in that contrast is reduced by reflection of light incident from the outside.

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic light emitting display device having a photodiode and a method of manufacturing the same, in order to adjust the luminance of light emitted according to the amount of light incident from the outside.

Another object of the present invention is to provide an organic light emitting display device capable of increasing the light receiving efficiency of a photodiode and a manufacturing method thereof.

An organic electroluminescent device according to an aspect of the present invention for achieving the above object is formed on a substrate, the substrate, a transistor including a gate, a source and a drain, connected to the transistor, the first electrode, the organic thin film layer And an organic light emitting diode including a second electrode, a photodiode for generating an electrical signal according to light incident from the outside, and a reflecting film for reflecting light incident from the outside to the photodiode.

According to another aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, including forming a reflective film on a predetermined portion of a substrate, and forming a buffer layer on an entire surface of the substrate including the reflective film. Forming first and second semiconductor layers on the reflective layer and on the buffer layer adjacent to the reflective film, forming PN junctions on the first semiconductor layer, and source and drain regions on the second semiconductor layer. And forming a channel region, forming a gate insulating layer on the entire surface including the first and second semiconductor layers, and then forming a gate electrode on the gate insulating layer above the channel region, and including the gate electrode. After the interlayer insulating film is formed on the entire surface, the interlayer insulating film and the gate insulating film are patterned to expose the source and drain regions. Forming a contact hole, forming a source and a drain electrode to be connected to the source and drain regions through the contact hole, and forming a planarization film on an entire surface thereof, and then planarizing the exposed portion of the source or drain electrode Forming a via hole in the film, forming a first electrode to be connected to the source or drain electrode through the via hole, and forming a pixel defining layer to expose a portion of the first electrode, and then over the exposed first electrode Forming an organic thin film layer on the pixel, and forming a cathode on the pixel defining layer including the organic thin film layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. no.

The organic material constituting the light emitting layer of the organic light emitting display device has a problem in that the brightness and the emitted light deteriorate as the film quality and properties deteriorate with time. In order to solve this problem, a method of controlling the brightness of light emitted by detecting light emitted from the outside or light emitted from the inside by using a photodiode has been developed. However, as the size and thickness of the display device are gradually reduced, the size of the photodiode is also reduced, which causes a problem in that the light receiving area and the efficiency are reduced.

According to the present invention, when light is incident from the outside, light passing through the photodiode and light traveling toward the substrate are reflected to be incident on the photodiode so that the light receiving efficiency is increased.

2 is a cross-sectional view illustrating an organic light emitting display device including a photodiode according to the present invention.

The reflective film 110 is formed on a predetermined portion of the substrate 100. The reflective film 110 is formed of a metal such as Ag, Mo, Ti, Al, or Ni in the non-light emitting region adjacent to the light emitting region. The buffer layer 120 is formed on the entire surface of the substrate 100 including the reflective film 110. A semiconductor layer 130a is provided on the buffer layer 120 on the reflective layer 110 to provide the PN junctions 131 and 132 and the intrinsic semiconductor 133, and the buffer layer in a portion adjacent to the semiconductor layer 130a is formed. The semiconductor layer 130b providing the source and drain regions 134 and 135 and the channel region 136 is formed on the 120. The gate electrode 150 is insulated from the semiconductor layer 130b by the gate insulating layer 140 on the semiconductor layer 130b, and the source and drain regions 134 and the upper surface of the semiconductor layer 130b are formed over the semiconductor layer 130b. An interlayer insulating layer 160 having contact holes formed to expose 135 is formed. Source and drain electrodes 170a and 170b connected to the source and drain regions 134 and 135 are formed on the interlayer insulating layer 160, and the entire upper surface including the source and drain electrodes 170a and 170b. A planarization layer 180 having a via hole formed therein is formed to expose the source or drain electrode 170a or 170b. On the planarization layer 180, a pixel defining layer 200 for exposing a portion of the anode electrode 190 to define a light emitting region and an anode electrode 190 connected to the source or drain electrode 170a or 170b through a via hole. ) And an organic thin film layer 210 and a cathode electrode 220 are formed on the anode electrode 180. The organic thin film layer 210 may have a structure in which a hole transport layer, an organic light emitting layer, and an electron transport layer are stacked, and further include a hole injection layer and an electron injection layer.

As described above, in the organic light emitting diode composed of the anode electrode 180, the organic thin film layer 210, and the cathode electrode 220, when a predetermined voltage is applied to the anode electrode 180 and the cathode electrode 220, the anode electrode 180 is formed. Holes injected through) and electrons injected through the cathode electrode 220 are recombined in the organic thin film layer 210, and emit light due to the energy difference generated in the process. As the light is emitted to the outside, light is incident on the organic light emitting device from an external light source. A photodiode composed of the PN junctions 131 and 132 and the intrinsic semiconductor 133 receives light incident from the outside. Generates an electrical signal based on the amount of light.

A photodiode is a semiconductor device that converts an optical signal into an electrical signal. A negative bias voltage is applied to the P junction 131 and a positive voltage is applied to the N junction 132. When light is incident in the applied state, electrons and holes move along a depletion region formed in the intrinsic semiconductor 133 so that a current flows. This outputs a voltage proportional to the amount of light. Therefore, the voltage applied to the anode electrode 180 and the cathode electrode 220 of the organic light emitting diode is adjusted according to the voltage output from the photodiode so that the luminance of the light emitted according to the amount of light incident from the outside is constant. Can be adjusted.

According to the present invention, when light is incident from the outside into the photodiode, the light is transmitted to the substrate 100 without being incident with the light passing through the photodiode to be reflected by the reflective film 110 to be incident to the photodiode. Allow for increased efficiency.

In general, the semiconductor layer 130a constituting the photodiode is formed of polysilicon, and is formed as thin as 500 kHz, so that it is difficult to obtain sufficient light receiving efficiency. In addition, as the size and thickness of the display device are gradually reduced, the size of the photodiode is also reduced, so that the light receiving efficiency is further lowered. However, when the present invention is applied, the light receiving efficiency is increased by the reflective film 110, thereby making it possible to reduce the size of the photodiode, thereby reducing the size of the display device.

Next, a method of manufacturing an organic light emitting display device according to the present invention configured as described above will be described with reference to FIGS. 3A to 3D.

Referring to FIG. 3A, a metal such as Ag, Mo, Ti, Al, or Ni is deposited on a substrate 100 by a sputtering method, or the like, and then patterned by an exposure and development process using a predetermined mask. The reflective film 110 is formed on the substrate. The metal for forming the reflective film 110 is deposited to a thickness sufficient to reflect light, for example, a thickness of 100 to 5000 kPa.

Referring to FIG. 3B, after the buffer layer 120 and the semiconductor layer 130 are sequentially formed on the entire surface of the substrate 100 including the reflective film 110, the semiconductor layer 130 is patterned to form the upper portion of the reflective film 110. The semiconductor layer 130a is allowed to remain, and the semiconductor layer 130b is allowed to remain on the buffer layer 120 adjacent to the reflective film 110. The buffer layer 120 is to prevent damage of the substrate 100 due to heat, and is formed of an insulating film such as silicon oxide film (SiO ₂ ) or silicon nitride film (SiNx), and the semiconductor layer 130 is formed of amorphous silicon or polysilicon. In the case of using amorphous silicon, it is crystallized through heat treatment.

Referring to FIG. 3C, PN junctions 131 and 132 are formed in the semiconductor layer 130a through N-type and P-type impurity ion implantation processes, and source and drain regions 134 and 135 and a channel are formed in the semiconductor layer 130b. Area 136 is formed. Therefore, a photodiode made of intrinsic semiconductor 133 between PN junctions 131 and 132 and PN junctions 131 and 132 is formed in semiconductor layer 130a, and source and drain regions 134 and 133 are formed in semiconductor layer 130b. A transistor consisting of channel region 136 between 135 and source and drain regions 134 and 135 is formed.

Referring to FIG. 3D, the gate insulation layer 140 is formed on the entire surface including the semiconductor layers 130a and 130b, and then the gate electrode 150 is formed on the gate insulating layer 140 on the channel region 136. do.

Referring to FIG. 3E, an interlayer insulating layer 160 is formed on the entire surface including the gate electrode 150. The interlayer insulating layer 160 and the gate insulating layer 140 are patterned to form contact holes so that the source and drain regions 134 and 135 of the semiconductor layer 130b are exposed, and the source and drain regions 134 and Source and drain electrodes 170a and 170b are formed to be connected to the 135.

Referring to FIG. 3F, after the planarization layer 180 is formed on the entire surface to planarize the surface, a via hole is formed in the planarization layer 180 so that a predetermined portion of the source or drain electrode 170a or 170b is exposed, and the via hole is formed. The anode electrode 190 is formed to be connected to the source or drain electrodes 170a and 170b through. After forming the pixel defining layer 200 on the planarization layer 180 to expose a portion of the anode electrode 190, the organic thin film layer 210 is formed on the exposed anode electrode 190. The organic thin film layer 210 may have a structure in which a hole transport layer, an organic light emitting layer, and an electron transport layer are stacked, and further include a hole injection layer and an electron injection layer.

Referring to FIG. 3G, the cathode electrode 220 is formed on the pixel defining layer 200 including the organic thin film layer 210 to form an organic layer including the anode electrode 190, the organic thin film layer 210, and the cathode electrode 220. Complete the electroluminescent diode.

In the above embodiment, in order to effectively reflect the light traveling toward the substrate 100, the reflective film 110 may be formed wider than the semiconductor layer 130a. In addition, in the above embodiment, a case in which the photodiode is configured to receive light incident from the outside has been described. However, the present invention is not limited thereto, and the anode and the cathode electrode 180 and the cathode electrode of the organic light emitting diode are formed by receiving light emitted from the inside. 220 may be configured to adjust the voltage applied thereto, and the organic light emitting diode may be configured to operate as a touch panel using a photo diode.

As described above, the preferred embodiment of the present invention has been disclosed through the detailed description and the drawings. The terms are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, when the light is incident from the outside, the light reception efficiency can be increased by allowing the light that passes in the direction of the substrate to be reflected by the reflecting film to the photodiode without being incident with the light passing through the photodiode. Therefore, since the light receiving efficiency is increased by the reflective film, it is possible to reduce the size of the photodiode, thereby reducing the size of the display device.

Claims (11)

Board; A transistor formed on the substrate, the transistor including a gate, a source, and a drain; An organic light emitting diode connected to the transistor and including a first electrode, an organic thin film layer, and a second electrode; Photo diodes for generating an electrical signal in accordance with the light incident from the outside; And A reflection film formed under the photodiode and reflecting light incident from the outside to the photodiode; And an luminance of light emitted from the organic light emitting diode according to the electrical signal generated from the photodiode. The organic light emitting device of claim 1, wherein the photodiode comprises an intrinsic semiconductor between the PN junction and the PN junction. delete The organic light emitting device of claim 1, wherein the reflective film is formed of one selected from the group consisting of Ag, Mo, Ti, Al, and Ni. The organic light emitting device of claim 1, wherein the reflective film is formed to a thickness of 100 to 5000 kPa. The organic light emitting device of claim 1, wherein the reflective film is formed wider than the photodiode. The organic light emitting device of claim 1, wherein a voltage applied to the first electrode and the second electrode is controlled by an electrical signal generated from the photodiode. Forming a reflective film on the substrate, Forming a buffer layer on the entire surface of the substrate including the reflective film; Forming first and second semiconductor layers on the reflective layer and on the buffer layer adjacent to the reflective layer, respectively; Forming a PN junction in the first semiconductor layer, and forming source and drain regions and a channel region in the second semiconductor layer, Forming a gate insulating film on the entire surface including the first and second semiconductor layers, and then forming a gate electrode on the gate insulating film over the channel region; Forming an interlayer insulating film on the entire surface including the gate electrode and patterning the interlayer insulating film and the gate insulating film to form contact holes to expose the source and drain regions; Forming source and drain electrodes to be connected to the source and drain regions through the contact hole; Forming a via hole in the planarization film to expose a predetermined portion of the source or drain electrode after forming the planarization film on the entire surface, and forming a first electrode to be connected to the source or drain electrode through the via hole; Forming a pixel defining layer to expose a portion of the first electrode and then forming an organic thin film layer on the exposed first electrode; Forming a cathode on the pixel defining layer including the organic thin film layer, According to the light incident from the outside, an electrical signal is generated from the photodiode including the PN junction, and the light emitted from the organic light emitting diode including the first electrode, the organic thin film layer, and the second electrode according to the electrical signal. A method of manufacturing an organic light emitting display device, the luminance of which is controlled. The method of claim 8, wherein the reflective film is formed of one selected from the group consisting of Ag, Mo, Ti, Al, and Ni. The method of manufacturing an organic electroluminescent device according to claim 8, wherein the reflective film is formed to a thickness of 100 to 5000 kPa. 10. The method of claim 8, wherein the reflective film is formed wider than the first semiconductor layer.

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