KR100722111B1 - Organic light emitting display device having photo diode - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display that forms an uneven portion on the light receiving side of a photodiode. One aspect of the present invention is an organic light emitting display device having an organic light emitting diode, and receives light emitted from the organic light emitting diode or light flowing from the outside, and converts the received light into a predetermined electrical signal to output the light. And photo diodes; And a light receiving layer formed on an optical path incident on the photodiode and having an uneven portion formed on a surface thereof.

Photodiode, light emitting diode, light receiving element

Description

Organic light emitting display device having a photodiode

1A is a cross-sectional view illustrating a structure of an organic light emitting display device having a photodiode according to an exemplary embodiment of the present invention.

1B is a cross-sectional view illustrating a structure of an organic light emitting display device having a photodiode according to another exemplary embodiment of the present invention.

2 is a circuit diagram illustrating an embodiment of an organic light emitting display device employing a photodiode for receiving internal light according to the present invention.

3 is a circuit diagram illustrating another embodiment of an organic light emitting display device employing an external light-receiving photodiode according to the present invention.

<Description of Major Symbols in Drawing>

100 substrate 110 buffer layer

120: thin film transistor 127: uneven portion

130: planarization layer 140: pixel defining layer

150: organic light emitting diode 160: photodiode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display having a photodiode, and more particularly, to an organic light emitting display for forming an uneven portion on the light receiving portion side of a photodiode.

 The photodiode PD 'is a kind of optical sensor that converts optical energy into electrical energy to obtain an electrical signal (current or voltage) from an optical signal. The photodiode PD' is a semiconductor device provided with a photodetection function at a junction of a diode. The photodiode PD 'basically uses the principle that the conductivity of the diode is modulated according to the optical signal by generating electrons or holes by photon absorption. That is, the current of the photodiode PD 'essentially changes with the optical generation rate of the carrier, and this characteristic converts the optical signal, which changes over time, into an electrical signal.

By using the above-described characteristics, research for applying a photodiode to a display field is continued. In particular, the photodiode may receive light or external light emitted by the organic light emitting diode and convert the light into an electrical signal, thereby adjusting the brightness of the organic light emitting diode 150.

However, the photodiode formed on the polycrystalline silicon substrate together with the organic light emitting diode has a problem of not being able to efficiently receive external light due to its small thickness, and the pixel area of the organic light emitting display can be widened by reducing the size of the photodiode. Research is underway to secure it.

An object of the present invention is to provide an organic light emitting display device having a photodiode having a high light receiving efficiency and a reduced size.

One aspect of the present invention is an organic light emitting display device having an organic light emitting diode, and receives light emitted from the organic light emitting diode or light flowing from the outside, and converts the received light into a predetermined electrical signal to output the light. And photo diodes; And a light receiving layer formed on an optical path incident on the photodiode and having an uneven portion formed on a surface thereof.

According to another aspect of the present invention, a method of manufacturing an organic light emitting display device including a photodiode, which receives light from an organic light emitting diode or an external device, converts the received light into a predetermined electrical signal, and outputs the photodiode. It characterized in that it comprises the step of forming a light receiving layer having a concave-convex portion on the surface on the optical path.

Hereinafter, an embodiment of an organic light emitting display device according to the present invention will be described in detail with reference to FIG. 1.

1A is a cross-sectional view illustrating an example of an organic light emitting diode display having a photodiode. Accordingly, the organic light emitting diode display including the photodiode includes the substrate 100, the buffer layer 110, the thin film transistor 120, the planarization layer 130, the pixel defining layer 140, the organic light emitting diode 150, and the photo. Diode 160 is included.

The substrate 100 has an insulating property such as glass, plastic, silicon, or synthetic resin, and is preferably formed of a transparent material.

The buffer layer 110 is formed on the substrate 100 and is formed of a nitride film or an oxide film. In this case, the buffer layer 110 is an optional component.

The thin film transistor 120 is formed on a predetermined region of the buffer layer 110, and includes a semiconductor layer 121, a gate insulating layer 122, a gate electrode 123, an interlayer insulating layer 124, and a source / drain electrode ( 125a, 125b). Meanwhile, the semiconductor layer 121 of the thin film transistor 120 may be formed by crystallizing amorphous silicon deposited on the substrate 100 with polysilicon, and is divided into a channel region 121a and an ohmic contact region 121b. .

The gate insulating layer 122 is formed on the semiconductor layer 121 to electrically insulate the gate electrode 123 from the source / drain 125a and 125b.

The gate electrode 123 is formed in at least one region of the gate insulating layer 122, and is preferably formed at a position corresponding to the channel region 121a of the semiconductor layer 121.

The interlayer insulating layer 124 is formed on the gate insulating layer 122 including the gate electrode 123 and the semiconductor layer 121.

The source / drain electrodes 125a and 125b are formed on the interlayer insulating layer 124, and the ohmic contact region of the semiconductor layer 121 is formed through a predetermined contact hole (not shown) formed through the interlayer insulating layer 124. It is formed so as to be electrically connected with 121b.

The planarization layer 130 is formed on the thin film transistor 120 and is preferably formed of a nitride film or an oxide film, but is not limited thereto.

The pixel defining layer 140 is formed in the planarization layer 130 and has a predetermined opening (not shown) to expose at least one region of the first electrode 150a. The pixel defining layer 140 may be made of one organic insulating material selected from the group consisting of an acryl-based organic compound, polyamide, and polyimide.

The organic light emitting diode 150 is formed on the planarization layer 130 and includes a first electrode 150a, an organic thin film layer 150b, and a second electrode 150c.

The first electrode 150a is formed on the planarization layer 130 and is electrically connected to any one of the source and drain electrodes 125a and 125b through a predetermined via hole (not shown) provided in the planarization layer 130. do.

The organic thin film layer 150b is formed on the first electrode 150a and has an opening (not shown) that exposes a region of the first electrode 150a. The organic thin film layer 150b may further include a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

The second electrode 150b is formed on the organic thin film layer 150c and may be formed of the same material as the first electrode 150a.

On the other hand, the photodiode 160 is formed on a predetermined region of the side where the transistor is formed on the buffer layer 110. For example, the organic light emitting device may be formed under the organic light emitting device or outside the pixel area, that is, the non-pixel area, in which the organic light emitting device is formed. In this case, the photodiode 160 is preferably formed on the same layer as the semiconductor layer 121 of the thin film transistor 120, and the n-type doped region 160a, the channel region 160b, and the p-type doped region ( 160c).

The n-type doped region 160a is formed by implanting high concentration ions of n-type impurities, and the p-type doped region 160c is formed by implanting high concentration ions of p-type impurities. In addition, the channel region 160b is preferably formed to be 3 mu m or more as an intrinsic semiconductor layer.

The insulating layer 124 on the photodiode is composed of the same layer as the gate insulating layer 124 of the organic light emitting diode, and between the photodiode 160 and other layers (not shown) to be stacked on the photodiode 160. It insulates against electrical influences.

The interlayer insulating layer 124 and the passivation layer 130 of the organic light emitting diode are formed to extend on the insulating layer 124, and the interlayer insulating layer 124 or the passivation layer 130 is patterned to include the uneven portion 127. do. The uneven portion 127 is provided with a plurality of semicircular projections (lens projections). The straightness of the light incident to the photodiode 160 from the outside through the uneven portion is increased to increase the light receiving rate.

Unlike the concave-convex portion in FIG. 1A, the concave-convex portion may be variously configured in a triangular prism shape, a semi-circular columnar shape, or a square columnar protrusion shape. Figure 1b is that the uneven portion is formed with a square pillar protrusion, thereby those skilled in the art will understand that the shape of the uneven portion is not limited.

 In this structure, the photodiode 160 may receive light from the outside, that is, light emitted from the organic light emitting diode or external light, and convert the light into an electrical signal, thereby adjusting the luminance of the organic light emitting diode 150. .

Hereinafter, the operation of the photodiode according to the present invention will be described with reference to the drawings.

First, referring to FIG. 2, an example in which the internal light of the photodiode light, that is, the light emitted by the organic light emitting diode is directly received and an emission level of the organic light emitting diode is adjusted, will be described.

Accordingly, the organic light emitting diode display according to the present invention includes a first transistor M1 ', a capacitor Cst', a second transistor M2 ', an organic light emitting diode OLED', and a photodiode PD '. do.

The gate of the first transistor M1 'is connected to the scan line Sn', the drain is connected to the gate of the second transistor M2 ', and the source is connected to the data line Dm'. The first transistor M1 'transfers a voltage corresponding to the data voltage applied to the data line Dm' to the capacitor Cst 'in response to a scan signal applied to the scan line Sn'.

The first power source ELVdd 'is applied to the first terminal of the capacitor Cst', and the second terminal is connected to the gate of the second transistor M2 '. The capacitor Cst 'stores the voltage corresponding to the data voltage applied to the data line Dm' in the period when the first transistor M1 'is on, and the period in which the first transistor M1' is off. While maintaining the voltage.

The gate of the second transistor M2 'is connected to the second terminal of the capacitor Cst', the first power source ELVdd 'is applied to the source, and the drain is connected to the anode electrode of the organic light emitting diode OLED'. do. The second transistor M2 'generates a current corresponding to the stored voltage of the capacitor and the first power source ELVdd' and supplies the current to the organic light emitting diode OLED '.

The photodiode PD 'is formed at at least one location that can receive a portion of the light of the organic light emitting diode OLED'. At this time, when the anode voltage and the cathode voltage are applied to the n doped region and the p doped region, respectively, the channel region becomes a depletion state, and an electric signal is generated by forming an electric charge along the light incident through the surface of the organic light emitting diode. If the luminance exceeds the reference value or does not reach the reference value, the luminance can be adjusted.

3 illustrates an operation according to an example in which a photodiode receives external light. Accordingly, the organic light emitting diode display according to the present invention includes a first transistor M1 ′, a second transistor M2 ″, a resistor R ″, and a photo diode PD ″.

The first transistor M1 ″ is connected between the first power supply Pw and the second power supply GND, and the reset signal RE is applied to the gate of the first transistor M1 ″.

The second transistor M2 ″ is connected between the first power supply Pw and the second power supply GND, and the photodiode PD ″ and the first transistor () are connected to the gate of the second transistor M2 ″. "A" potential, which is the connection point of M1 "), is supplied.

The resistor R '' is extracted from both ends of the output terminals P1 and P2, and the output voltage Vout between P1 and P2 is output as the external light detection voltage.

The photodiode PD ″ is connected to the drain of the first transistor M1 ″ and the second power source GND, and the cathode and anode terminals are arranged in a reverse-bias structure. The first transistor M1 ″ and the second transistor M2 ″ may be either an N-type or P-type transistor, but the present invention will be described with reference to an N-type transistor.

Referring to the operation of the circuit having the above structure, first, when the reset signal RE is at the high level, the first transistor M1 ″ is turned on, and thus, the gate of the second transistor M2 ″ is connected to the first transistor. The first power source Pw is applied through M1 ″. Accordingly, the second transistor M2 ″ is also turned on by the gate voltage corresponding to the first power source Pw. During this reset period, the output voltage Vout becomes constant if the impedance of the second transistor M2 &quot; is sufficiently smaller than the resistance value of the resistor R &quot;, and the photocurrent (diode) flowing through the photodiode PD &quot; Reverse current).

For this reason, when the photodiode PD '' receives light, a photocurrent is generated accordingly, and the potential A of the photodiode PD '' drops. As a result, the gate potential of the second transistor M2 &quot; drops so that the impedance becomes small. Therefore, the output voltage Vout also becomes small.

According to the above operation, since the output voltage Vout according to the external light intensity can be adjusted, the amplitude of the data signal Dm is adjusted according to the output voltage Vout, thereby adjusting the light emission intensity of the organic light emitting diode (not shown). I can regulate it.

Next, a method of forming an embodiment of an organic light emitting display device having a photodiode according to the present invention will be described. The photodiode according to the present embodiment may be implemented in both an active driving type organic light emitting device or a passive driving type organic light emitting device, but in the present embodiment, the active driving type organic light emitting device will be described as an example.

In the present embodiment, the photodiode is fabricated simultaneously with the process of forming the driving thin film transistor formed on the substrate in the active driving organic light emitting diode.

That is, referring back to FIG. 1, the buffer layer 110 is formed on the deposition substrate 100. The buffer layer 110 is to prevent damage to the substrate 100 due to heat, and is formed of an insulating film such as silicon oxide film SiO2 or silicon nitride film SiNx.

The semiconductor layer 121 is formed on the buffer layer 110 and the remaining portions are etched while leaving only portions necessary for the region where the thin film transistor 120 is to be formed and the region where the photodiode 160 is to be formed. The active layer 121a and the ohmic contact layer 121b are formed by doping the semiconductor layer 121 of the thin film transistor 120, and the channel layer and the doped region are formed by doping the semiconductor layer of the photodiode 160. One of the doped regions is doped with n-type impurities and the other is doped with p-type impurities.

Next, the gate insulating layer 122 is formed on the entire upper surface including the semiconductor layer 131.

Next, after the gate electrode 123 is patterned on the gate insulating layer 122 on the semiconductor layer 131, the interlayer insulating layer 124 is formed on the entire upper surface including the gate electrode 123. The interlayer insulating film 124 is also formed over the entire region. At this time, the uneven portion is patterned on the region where the photodiode 160 is formed. The uneven portion may have a triangular prism shape, a semi-circular body shape, a semi-elliptic shape, or a square pillar shape protrusion.

Next, contact holes are formed by patterning the interlayer insulating layer 124 and the gate insulating layer 122, and source and drain electrodes 125a and 125b are formed to be connected to the semiconductor layer 124 through the contact holes.

After the surface is planarized with the protective layer 130, a via hole is formed in the protective layer 130, and the anode electrode 150a is formed to be connected to the source or drain electrodes 125a and 125b through the via hole.

After forming the pixel defining layer 140 on the protective layer 130 to expose a portion of the anode electrode 150a, the organic thin film layer 150b is formed on the exposed anode electrode 150a.

The organic thin film layer 150b may have a multilayer structure including a hole injection layer HIL, a hole transport layer HTL, an organic thin film layer EML, an electron transport layer ETL, and an electron injection layer EIL.

The organic light emitting display device is manufactured by forming the cathode electrode 150c on the pixel defining layer 130 including the organic thin film layer 150b.

Although the present invention has been described primarily with reference to the above embodiments, many other possible modifications and variations can be made without departing from the spirit and scope of the invention. For example, the shape of the irregularities of the uneven portion or having a separate layer forming the uneven portion, the change in the width of the channel region of the formed photodiode, the change in the thickness of the buffer layer, or the like will be the case.

The organic light emitting diode display according to the present invention has a photodiode therein, and thus the luminance can be adjusted according to the intensity of the internal light and the external light.

In addition, an uneven portion is formed on the photodiode to increase the light receiving efficiency of the light, and the photodiode with the increased light receiving efficiency has an effect of reducing the size of the device to expand the pixel area of the organic light emitting display device.

The scope of the above-described invention is defined in the following claims, and is not bound by the description in the text of the specification, all modifications and variations belonging to the equivalent scope of the claims will fall within the scope of the present invention.

Claims (7)

In an organic light emitting display device having an organic light emitting diode, A photo diode which receives the light emitted from the organic light emitting diode or the light flowing from the outside, converts the received light into a predetermined electrical signal, and outputs the converted light; And And a light receiving layer formed on an optical path incident on the photodiode and having an uneven portion formed on a surface thereof. The method of claim 1, The organic light emitting display device includes a driving transistor layer that sequentially includes a semiconductor layer, a gate insulating layer, a gate electrode, an interlayer insulating layer, and a source / drain electrode on a substrate, wherein the light receiving layer is formed with the photodiode. And an interlayer insulating layer extending upwardly. The method of claim 1, The organic light emitting display device further comprises a protective layer on the source / drain electrodes, wherein the light receiving layer is the protective layer extending above the photodiode. The method of claim 1, The concave-convex portion of the organic light emitting display device, characterized in that a plurality of triangular columnar, semi-circular, semi-elliptic, or square columnar projections. An organic light emitting diode or a method for manufacturing an organic light emitting display device including a photodiode by converting the received light into a predetermined electrical signal and outputting the light. A method of manufacturing an organic light emitting display device, the method comprising: forming a light receiving layer having irregularities on a surface thereof on an optical path incident on the photodiode. The method of claim 5, And forming the light receiving layer simultaneously with the driving transistor interlayer insulating layer of the organic light emitting diode. The method of claim 5, And the light receiving layer is formed at the same time as the driving transistor protective layer of the organic light emitting diode.

Images