WO2009017339A2

WO2009017339A2 - Organic light-emitting transistors and method of the same, and active matrix organic light-emitting displays and method of the same

Info

Publication number: WO2009017339A2
Application number: PCT/KR2008/004363
Authority: WO
Inventors: Young-Kyoo Kim
Original assignee: Kyungpook National University Industry-Academic Cooperation Foundation
Priority date: 2007-07-27
Filing date: 2008-07-25
Publication date: 2009-02-05
Also published as: WO2009017339A3

Abstract

An organic light emitting transistor, an active matrix organic light emitting display device having the organic light emitting transistor, and manufacturing methods thereof. The organic light emitting transistor includes a lower electrode formed in a predetermined pattern on one side of a substrate; a pair of insulating films formed on upper surface portions of the lower electrode, spaced apart from each other; first and second gate electrodes layered on upper surface portions of the insulating films; an organic semiconductor thin film layer coated on an upper surface of a portion of the lower electrode, which is not coated with any one of the first and second gate electrodes and the insulating thin films; and an upper electrode formed on an upper surface portion the semiconductor thin film layer.

Description

ORGANIC LIGHT-EMITTING TRANSISTORS AND METHOD OF THE SAME, AND ACTIVE MATRIX ORGANIC LIGHT- EMITTING DISPLAYS AND METHOD OF THE SAME

Technical Field

[I] The present invention relates to an organic light emitting transistor, an active matrix organic light emitting display device having the organic light emitting transistor, and manufacturing methods thereof.

Background Art

[2] In general, a flat panel display device, such as a liquid display device (LCD) or an electroluminescence display device (ELD), uses a thin film transistor as a switching device to control operations of respective pixels and as a drive device for the pixels.

[3] As recently demanded, there are continuous attempts to use a plastic substrate made instead of a conventional glass substrate in order to make the flat panel display device large, thin and flexible.

[4] However, the use of the plastic substrate requires a low temperature process instead of a high temperature process. As a drawback, this makes it difficult to use a conventional silicon thin film transistor.

[5] In order to overcome this problem, a number of studies have been carried out in recent years on an organic thin film transistor (OTFT) that uses, as a semiconductor layer, an organic film feasible for a low temperature process.

[6] FIG. 1 is a cross-sectional view illustrating an organic transistor disclosed in US

Patent No. 7,126,153 (hereinafter, referred to as 'earlier patent 1').

[7] Referring to FIG. 1 disclosing the organic transistor, comb- or mesh-shaped floating electrodes are interposed between upper and lower electrodes to act as gate electrodes.

[8] However, in the organic transistor disclosed in the earlier patent 1, exciton decay can take place by natural quenching on the surface of the electrodes due to presence of the floating electrodes inside an organic thin film layer, and reliability of stripping can be affected due to presence of the metal electrodes inside the organic thin film layer.

[9] FIG. 2 is a cross-sectional view illustrating an organic transistor disclosed in US

Patent No. 6,897,621 (hereinafter, referred to as 'earlier patent document T).

[10] Referring to FIG. 2 disclosing an organic transistor structure, a gate electrode is arranged in a position parallel to a lower electrode. The organic transistor applies a voltage between the gate electrode and an upper electrode for the purpose of control.

[I I] In the organic transistor disclosed in earlier patent 2, however, the gate electrode does not perform the gate function of a typical transistor. Rather, this organic transistor is constructed such that luminance additionally increases or decreases in response to a voltage, which is applied between the gate electrode and a cathode, namely, an upper electrode, in a direction the same as or reverse to that of a basic light emitting device. Thus, the structure of earlier patent 2 may not be regarded as a true transistor.

[12] This document discloses merely a simple structure in which two light emitting diodes are connected in parallel since a connecting portion between the gate electrode and the upper electrode acts merely as an auxiliary electrode.

[13] FIG. 3 is a cross-sectional view illustrating a thin-film transistor monolithically integrated with an organic light emitting diode, disclosed in US Patent No. 6,150,668 (hereinafter, referred to as 'earlier patent document 3').

[14] Claim 1 of the earlier patent 3 describes "a device comprising a light emitting diode monolithically integrated with at least one thin-film transistor wherein the light emitting diode comprises an anode, a cathode and at least one active layer comprising a light-emitting material sandwiched between the anode and the cathode and the thin- film transistor comprises a gate and a semiconductor material interposed between source and drain contacts such that a current that flows from the source to the drain flows through the semiconductor material from the source to the drain, wherein the thin-film transistor and the light emitting diode are formed on a single, unitary substrate, wherein the semiconductor material of the thin-film transistor and at least one active layer of the light emitting diode is an organic material and one of either the anode or the cathode of the light emitting diode and the gate of the thin-film transistor are the same material and are formed on a common surface," which is more easily understandable with reference to FIG. 1 appended in the same document.

[15] In earlier patent 3 constructed as above, a thin-film transistor (TFT) has to be made according to a conventional method of forming lower gate electrodes. Specifically, all electrodes of the TFT are prepared, followed by forming a semiconductor layer on the electrode so as to complete the TFT and then by sequentially coating an electron transporter/emitter layer (ETL) and a cathode so as to secondarily complete an organic light emitting display device (OLED).

[16] FIG. 4 is a cross-sectional view illustrating an active organic electroluminescent display device having an organic thin-film transistor, disclosed in US Patent No. 7,173,378 (hereinafter, referred to as 'earlier patent 4').

[17] Claim 1 of the earlier patent 4 describes "an active matrix organic electroluminescent display device including an organic thin-film transistor, the display device comprising: a counter electrode; an intermediate layer including at least a light emitting layer on the counter electrode; a pixel electrode formed on the intermediate layer; a first electrode disposed on the pixel electrode and insulated from the pixel electrode; a second electrode disposed on the pixel electrode and connected to the pixel electrode; a p-type organic semiconductor layer contacting the first electrode and a first drain electrode; and a first gate electrode disposed on the p-type organic semiconductor layer and insulated from the first electrode, the first drain electrode, and the p-type organic semiconductor layer," which is more easily understandable with reference to FIG. 2 appended in the same document.

[18] As described above, the earlier patent 4 has a structure in which the OTFT and the

OLED are stacked on each other. In the earlier patent 4 having such a stacked structure of the OTFT and the OLED, the OLED located under the OTFT is damaged by some process problems such as high temperature when the OTFT is being formed.

[19]

Disclosure of Invention Technical Problem

[20] The present invention has been made to solve the foregoing problems with the prior art, and a first aspect of the present invention is to provide an organic thin film transistor (OTFT) and a manufacturing method thereof, which can overcome drawbacks of a conventional OTFT, such as a small light emitting area and a high voltage, by forming an organic semiconductor thin film layer between upper and by forming lower electrodes and gate electrodes on both sides of the organic semiconductor thin film layer, and in which a device can be activated to emit light in response to electrical doping of the organic semiconductor thin film layer by an electric field between the gate electrodes on the sides.

[21] A second aspect of the present invention is to provide an OTFT and a manufacturing method thereof, which can overcome drawbacks of a conventional OTFT, such as a small light emitting area and a high voltage, by forming an organic semiconductor thin film layer between upper and lower electrodes and by forming upper gate electrodes on both sides of the organic semiconductor thin film layer and lower gate electrodes on both sides of the organic semiconductor thin film layer, and in which a device can be activated to emit light in response to electrical doping of the organic semiconductor thin film layer by an electric field between the upper and lower gate electrodes on the sides.

[22] A third aspect of the present invention is to provide an OTFT, which has a directly- connected structure between a drive part (transistor) and a lower electrode of a light emitting part, and a manufacturing method thereof, in which the lower electrode acts as both a gate of the drive part and an anode or cathode of the light emitting part, one of upper electrodes acts as both a source electrode of the transistor and a cathode or anode of the light emitting part, an organic thin film layer for actually emitting light does not have an electrode, and the light emitting part is separated, so as to improve reliability by preventing exciton decay and also achieve economic merits associated with manufacturing by simplifying a device structure.

[23] A fourth aspect of the present invention is to provide an active matrix organic light emitting display device (AMOLED) and a manufacturing method thereof, in which an OTFT and an organic light emitting display device (OLED) are incorporated into one body and can be simultaneously formed; a drain electrode of the OTFT is configured to also act as an anode (or a cathode) of the OLED so that currents can flow from a source to a drain so as to activate the OLED when a gate electrode of the OTFT is turned on; the gate electrode of OTFT is simultaneously deposited when an upper electrode of the OLED is deposited so that both the OLED and the OTFT can be manufactured in a one-step process; the drain electrode of the OTFT can be configured to be shared as one electrode of the OLED and the gate electrode of the OTFT can be configured to be shared as the other electrode of the OLED; and the interval between the source and the drain of the OTFT can be properly adjusted in a lithography process so that the amount of currents flowing from the source to the drain can be previously controlled in the process.

[24] A fifth aspect of the present invention is to provide an AMOLED and a manufacturing method thereof, in which an OTFT, an organic capacitor (OCAP) and an organic light emitting display device (OLED) are incorporated into one body and can be simultaneously formed; a drain electrode of the OTFT is configured to also act as an anode (or a cathode) of the OLED so that currents can flow from a source to a drain so as to activate the OLED when a gate electrode of the OTFT is turned on; the gate electrode of OTFT and an upper electrode of the OCAP are simultaneously deposited when an upper electrode of the OLED is deposited so that both the OLED and the OTFT can be manufactured in a one-step process; and the drain electrode of the OTFT can be configured to be shared as one electrode of the OLED, and the gate electrode of the OTFT can be configured to be shared as the other electrodes of the OLED and OCAP.

[25] In an exemplary embodiment according to the first aspect of the invention, the organic light emitting transistor may include a lower electrode formed in a predetermined pattern on one side of a substrate; a pair of insulating films formed on upper surface portions of the lower electrode, spaced apart from each other; first and second gate electrodes layered on upper surface portions of the insulating films; an organic semiconductor thin film layer coated on an upper surface of a portion of the lower electrode, which is not coated with any one of the first and second gate electrodes and the insulating thin films; and an upper electrode formed on an upper surface portion the semiconductor thin film layer.

[26] The lower electrode may act as a source or drain electrode. [27] The upper electrode may act as a drain or source electrode.

[28] The organic light emitting transistor may further include nano-particles or nano-lines selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[29] Here, the nano-particles or nano-lines may be made of one selected from an organic material, an inorganic material and metal.

[30] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[31] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to increase ionization potential so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[32] The substrate may be made up of a transparent substrate.

[33] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[34] In another exemplary embodiment according to the first aspect of the invention, the method of manufacturing an organic light emitting transistor may include steps of (a) layering a lower electrode in a predetermined pattern on one side of a substrate; (b) forming insulating films on both upper edges of the lower electrode and patterning the insulating films; (c) layering first and second gate electrodes on upper surface portions of the lower electrode, the first gate electrode spaced apart from the second gate electrode at a predetermined interval; (d) coating an organic semiconductor thin film layer on an upper surface of a portion of the lower electrode, which is not coated with any one of the first and second electrodes and the insulating films; and (e) forming an upper electrode on an upper surface portion of the organic semiconductor thin film layer.

[35] The lower electrode may act as a source or drain electrode.

[36] The upper electrode may act as a drain or source electrode.

[37] nano-particles or nano-lines may be selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[38] Here, the nano-particles or nano-lines may be made of one selected from an organic material, an inorganic material and metal. [39] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[40] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to increase ionization potential so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[41] The substrate may be made up of a transparent substrate.

[42] The substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[43] In an exemplary embodiment according to the second aspect of the invention, the organic light emitting transistor may include a lower electrode formed in a predetermined pattern on one side of a substrate; a pair of insulating films formed on upper surface portions of the lower electrode, spaced apart from each other; lower first and second gate electrodes layered on upper surface portions of the insulating films; an organic semiconductor thin film layer coated on an upper surface of a portion of the lower electrode, which is not coated with any one of the lower first and second gate electrodes and the insulating thin films; and upper first and second gate electrodes and an upper electrode formed on upper surface portions the semiconductor thin film layer.

[44] The lower electrode may act as a source or drain electrode.

[45] The lower electrode may act as a drain or source electrode.

[46] The organic light emitting transistor may further include or lower nano-particles or nano-lines selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[47] The nano-particles or nano-lines may be made of one selected from an organic material, an inorganic material and metal.

[48] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the lower first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer, and another portion of the organic semiconductor thin film layer in contact with the upper electrode is electrically doped by a voltage applied between the upper first and second gate electrodes so that electrons are injected so as to emit light.

[49] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped to increase ionization potential by a voltage applied to the first and second gate electrodes so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[50] The substrate may be made up of a transparent substrate.

[51] The substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[52] The upper first and second gate electrodes and the lower first and second gate electrodes may be simultaneously or separately controlled.

[53] The upper first and second gate electrodes and the upper electrode may be formed simultaneously.

[54] In another exemplary embodiment according to the second aspect of the invention, the method of manufacturing an organic light emitting transistor may include steps of (a) layering a lower electrode in a predetermined pattern on one side of a substrate; (b) forming insulating films on both upper edges of the lower electrode and patterning the insulating films; (c) layering lower first and second gate electrodes on upper surface portions of the lower electrode, the lower first gate electrode spaced apart from the second gate electrode at a predetermined interval; (d) coating an organic semiconductor thin film layer on an upper surface of a portion of the lower electrode, which is not coated with any one of the lower first and second electrodes and the insulating films; and (e) forming upper first and second gate electrodes and an upper electrode on an upper surface portion of the organic semiconductor thin film layer.

[55] The lower electrode may act as a source or drain electrode.

[56] The upper electrode may act as a drain or source electrode.

[57] Upper or lower nano-particles or nano-lines may be selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[58] Here, the nano-particles or nano-lines may be made of one selected from an organic material, an inorganic material and metal.

[59] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the lower first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer, and another portion of the organic semiconductor thin film layer in contact with the upper electrode is electrically doped by a voltage applied between the upper first and second gate electrodes so that electrons are injected so as to emit light.

[60] The organic semiconductor thin film layer in contact with the lower electrode may act as a hole injection layer, in which a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped to increase ionization potential by a voltage applied to the first and second gate electrodes so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[61] The substrate may be made up of a transparent substrate.

[62] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[63] The upper first and second gate electrodes and the lower first and second gate electrodes may be simultaneously or separately controlled.

[64] The upper first and second gate electrodes and the upper electrode may be formed simultaneously.

[65] In an exemplary embodiment according to the third aspect of the invention, the organic light emitting transistor may include a lower electrode formed in a predetermined pattern on one side of a substrate; an insulating film formed on an upper surface portion of the lower electrode; an organic semiconductor thin film layer covering upper surfaces of the lower electrode and the insulating film; an upper drain electrode formed on an upper surface portion of the organic semiconductor thin film layer coated on the insulating film; and an upper source electrode formed on another upper surface portion of the organic semiconductor thin film layer and, spaced apart from the upper drain electrode at a predetermined interval.

[66] The upper drain electrode may act as a cathode or anode of a light emitting part.

[67] In another exemplary embodiment according to the third aspect of the invention, the organic light emitting transistor may include a lower electrode formed in a predetermined pattern on one side of a substrate; an insulating film formed on an upper surface portion of the lower electrode; an organic semiconductor thin film layer covering upper surfaces of the lower electrode and the insulating film; an upper source electrode formed on an upper surface portion of the organic semiconductor thin film layer coated on the insulating film; and an upper drain electrode formed on another upper surface portion of the organic semiconductor thin film layer, spaced apart from the upper source electrode at a predetermined interval.

[68] The upper source electrode may act as a cathode or anode of a light emitting part.

[69] The lower electrode may act as an anode or cathode of the light emitting part as well as a gate electrode of a drive part.

[70] Here, an electron channel or a hole channel may be formed in the organic semiconductor thin film in contact with the insulating film by a voltage applied to the lower electrode.

[71] The organic light emitting transistor may have a directly-shared electrode structure, in which electron mobility of a device is controlled by adjusting a channel width of the upper electrodes.

[72] The substrate may be made up of a transparent substrate.

[73] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[74] In a further exemplary embodiment according to the third aspect of the invention, the method of manufacturing an organic light emitting transistor may include steps of (a) layering a lower electrode in a predetermined pattern on one side of a substrate; (b) forming an insulating film on an upper surface portion of the lower electrode and patterning the insulating film; (c) coating an organic semiconductor thin film layer on an upper surface of the insulating film; (d) forming an upper source electrode on an upper surface portion of the organic semiconductor thin film layer coated on the insulating layer; and (e) forming an upper drain electrode in a position spaced apart from the upper source electrode at a predetermined interval.

[75] The upper drain electrode may act as a cathode or anode of a light emitting part.

[76] In yet further exemplary embodiment according to the third aspect of the invention, the method of manufacturing an organic light emitting transistor may include steps of (a) layering a lower electrode in a predetermined pattern on one side of a substrate; (b) forming an insulating film on an upper surface portion of the lower electrode and patterning the insulating film; (c) coating an organic semiconductor thin film layer on an upper surface of the insulating film; (d) forming an upper drain electrode on an upper surface portion of the organic semiconductor thin film layer coated on the insulating layer; and (e) forming an upper source electrode in a position spaced apart from the upper source electrode at a predetermined interval.

[77] The upper drain electrode may act as a cathode or anode of a light emitting part.

[78] The lower electrode may act as an anode or cathode of the light emitting part as well as a gate electrode of a drive part.

[79] An electron channel or a hole channel may be formed in the organic semiconductor thin film in contact with the insulating film by a voltage applied to the lower electrode.

[80] A directly-shared electrode structure may be embodied to control electron mobility of a device by adjusting a channel width of the upper electrodes.

[81] The substrate may be made up of a transparent substrate.

[82] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[83] In an exemplary embodiment according to the fourth aspect of the invention, the

AMOLED, in which an OTFT is embedded, may include a source electrode of the OTFT formed in a predetermined pattern on one side of a substrate; a drain electrode of the OTFT formed in a predetermined pattern on the one side of the substrate and spaced apart from the source electrode at a predetermined interval, the drain electrode also used as a first electrode of the OLED; an organic thin film layer formed on the substrate to cover the source and drain electrodes of the OTFT; a gate electrode of the OTFT formed in a predetermined pattern on the organic thin film layer; a second electrode of the OLED formed in a predetermined pattern on the organic thin film layer; a gate dielectric layer of the OTFT formed between the gate electrode of the OTFT and the organic thin film layer; and an electron injection layer of the organic light emitting layer formed between the second electrode of the OLED and the organic thin film layer.

[84] The interval between the drain electrode and the source electrode of the OTFT may be adjusted by lithography to control currents flowing from the source electrode to the drain electrode at a predetermined amount.

[85] The gate electrode of the OTFT may be deposited together with the second electrode of the OLED, whereby the OLED and the OTFT are manufactured in one process.

[86] The first electrode of the OLED may act as an anode, and the second electrode of the

OLED may act as a cathode.

[87] The first electrode of the OLED may act as a cathode, and the second electrode of the

OLED may act as an anode.

[88] In another exemplary embodiment according to the fourth aspect of the invention, the method of manufacturing an AMOLED, in which an OTFT is embedded, may include steps of (a) forming a drain electrode and a source electrode of the OTFT in a predetermined pattern on one side of a substrate, the drain electrode of the OLED also used as a first electrode of the OLED; (b) forming an organic thin film layer on the substrate to cover the source electrode and the drain electrode of the OTFT; (c) forming a dielectric layer and a conductive layer sequentially on the organic thin film layer; (d) patterning the conductive layer and the dielectric layer in a predetermined form; and (e) forming a contact hole by etching the conductive layer and the dielectric layer to expose the organic thin film layer so that the dielectric layer and the conductive layer on one side of the contact hole form a gate dielectric layer and a gate electrode of the OTFT and the dielectric layer and the conductive layer on another side of the contact hole form an electron injection layer and a second electrode of the OLED.

[89] The interval between the drain electrode and the source electrode of the OTFT may be adjusted by lithography to control currents flowing from the source electrode to the drain electrode at a predetermined amount.

[90] The step (a) of forming a drain electrode and a source electrode of the OTFT may deposit a conductive material on the one side of the substrate, followed by lithography, to form the drain electrode and the source electrode.

[91] The step (a) of forming a drain electrode and a source electrode of the OTFT may perform vacuum deposition or spin coating to form the drain electrode and the source electrode.

[92] The gate electrode of the OTFT may be deposited together with the second electrode of the OLED, whereby the OLED and the OTFT are manufactured in one process.

[93] The first electrode of the OLED may act as an anode, and the second electrode of the

OLED may act as a cathode.

[94] The first electrode of the OLED may act as a cathode, and the second electrode of the

OLED may act as an anode.

[95] The organic thin film layer may be made up of a single layer or multi-layers.

[96] The substrate may be made up of a transparent substrate.

[97] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[98] In an exemplary embodiment according to the fifth aspect of the invention, the

AMOLED, in which an OTFT and an OCAP are embedded, may include a source electrode of the OTFT formed in a predetermined pattern on one side of a substrate; a drain electrode of the OTFT formed in a predetermined pattern on the one side of the substrate and spaced apart from the source electrode at a predetermined interval, the drain electrode also used as a first electrode of the OLED; a lower electrode of the OCAP formed on the one side of the substrate, spaced apart from the drain electrode at a predetermined interval; an organic thin film layer formed on the substrate to cover the source and drain electrodes of the OTFT and the lower electrode of the OCAP; and a gate electrode of the OTFT formed in a predetermined pattern on the organic thin film layer; a second electrode of the OLED formed in a predetermined pattern on the organic thin film layer; and an upper electrode of the OCAP formed in a predetermined pattern on the organic thin film layer.

[99] An opening ratio may be maximized by adjusting size ratios of the OTFT, the OLED and the OCAP.

[100] The first electrode of the OLED may act as an anode, and the second electrode of the OLED may act as a cathode.

[101] The first electrode of the OLED may act as a cathode, and the second electrode of the OLED may act as an anode.

[102] The AMOLED may further include an organic/inorganic doping layer layered on an upper surface portion the lower electrode of the OCAP in forming of the organic thin film layer.

[103] In another exemplary embodiment according to the fifth aspect of the invention, the method of manufacturing an OLED, in which an OTFT and an OCAP are embedded, the method may include steps of (a) forming a drain electrode and a source electrode of the OTFT and a lower electrode of the OCAP in a predetermined pattern onone side of a substrate, the drain electrode of the OLED also used as a first electrode of the OLED; (b) forming an organic thin film layer on the substrate to cover the source electrode and the drain electrode of the OTFT and the lower electrode of the OCAP; (c) forming a dielectric layer and a conductive layer sequentially on the organic thin film layer; (d) patterning the conductive layer and the dielectric layer in a predetermined form; and (e) forming a gate electrode and a second electrode of the OTFT and the upper electrode of the OCAP by etching the conductive layer and the dielectric layer to expose the organic thin film layer.

[104] An opening ratio may be adjusted by changing size ratios of the OTFT, the OLED and the OCAP.

[105] The step (a) of forming a drain electrode and a source electrode of the OTFT may deposit a conductive material on the one side of the substrate, followed by lithography, to form the drain electrode and the source electrode.

[106] The step (a) of forming a drain electrode and a source electrode of the OTFT may perform vacuum deposition or spin coating to form the drain electrode and the source electrode.

[107] The first electrode of the OLED may act as an anode, and the second electrode of the OLED may act as a cathode.

[108] The first electrode of the OLED may act as a cathode, and the second electrode of the OLED may act as an anode.

[109] The organic thin film layer may be made up of a single layer or multi-layers.

[110] The substrate may be made up of a transparent substrate.

[I l l] Here, the substrate may be made of one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[112] An organic/inorganic doping layer may be formed to be layered on an upper surface portion of the lower electrode of the OCAP in the forming of the organic thin film layer.

[113] According to the first aspect of the present invention as set forth above, the OTFT and the manufacturing method thereof can overcome drawbacks of a conventional OTFT, such as a small light emitting area and a high voltage, by forming the organic semiconductor thin film layer between the upper and lower electrodes and by forming the gate electrodes on both sides of the organic semiconductor thin film layer. Further, the device can be activated to emit light in response to electrical doping of the organic semiconductor thin film layer by an electric field between the gate electrodes on the sides. [114] According to the second aspect of the present invention, the OTFT and the manufacturing method thereof can overcome drawbacks of a conventional OTFT, such as a small light emitting area and a high voltage, by forming the organic semiconductor thin film layer between the upper and lower electrodes and by forming the upper gate electrodes on both sides of the organic semiconductor thin film layer and the lower gate electrodes on both sides of the organic semiconductor thin film layer. Further, the device can be activated to emit light in response to electrical doping of the organic semiconductor thin film layer by an electric field between the upper and lower gate electrodes on the sides.

[115] According to the third aspect of the present invention, the OTFT and the manufacturing method thereof provide a directly-connected structure between the drive part (transistor) and the lower electrode of the light emitting part. Here, the lower electrode acts as both the gate of the drive part and the anode or cathode of the light emitting part, one of the upper electrodes acts as both the source electrode of the transistor and the cathode or anode of the light emitting part, the organic thin film layer for actually emitting light does not have an electrode, and the light emitting part is separated, so as to improve reliability by preventing exciton decay and also achieve economic merits associated with manufacturing by simplifying the device structure.

[116] According to the fourth aspect of the present invention, the drain electrode of the

OTFT is configured to also act as the anode (or cathode) of the OLED so that currents can flow from the source to the drain so as to activate the OLED when the gate electrode of the OTFT is turned on. In particular, the gate electrode of OTFT is simultaneously deposited when the upper electrode of the OLED is deposited so that both the OLED and the OTFT can be manufactured in a one-step process, which is economically advantageous. Further, the interval between the source and the drain of the OTFT can be properly adjusted in a lithography process so that the amount of currents flowing from the source to the drain can be previously controlled in the process. Accordingly, this aspect is very economical compared to a conventional separated structure and has an advantage capable of maximizing the opening ratio.

[117] According to the fifth aspect of the present invention, the drain electrode of the

OTFT is configured to also act as the anode (or cathode) of the OLED so that currents can flow from the source to the drain so as to activate the OLED when the gate electrode of the OTFT is turned on. In particular, the gate electrode of OTFT and an upper electrode of the OCAP are simultaneously deposited when an upper electrode of the OLED is deposited so that both the OLED and the OTFT can be manufactured in a one-step process, which is economically advantageous. Further, since the size ratio of the OTFT, the OLED and the OCAP can be properly changed, this aspect is very economical compared to a conventional separated structure and has an advantage capable of adjusting the opening ratio. [118]

Brief Description of the Drawings

[119] FIG. 1 is a cross-sectional view illustrating an organic transistor disclosed in earlier patent 1;

[120] FIG. 2 is a cross-sectional view illustrating an organic transistor disclosed in earlier patent 2;

[121] FIG. 3 is a cross-sectional view illustrating a thin-film transistor (TFT) mono- lithically integrated with an organic light-emitting diode (OLED), disclosed in earlier patent 3;

[122] FIG. 4 is a cross-sectional view illustrating an active matrix organic electroluminescent display device having an organic TFT, disclosed in earlier patent 4;

[123] FIG. 5 is a cross-sectional view illustrating an organic light emitting transistor according to a first exemplary embodiment of the present invention;

[124] FIG. 6 is a cross-sectional view illustrating an organic light emitting transistor according to a second exemplary embodiment of the present invention;

[125] FIG. 7 is a cross-sectional view illustrating an organic light emitting transistor according to a third exemplary embodiment of the present invention;

[126] FIG. 8 is a cross-sectional view illustrating an alternative to the organic light emitting transistor according to the third exemplary embodiment of the present invention;

[127] FIG. 9 is a cross-sectional view illustrating an active matrix organic electroluminescent display device according to a fourth exemplary embodiment of the present invention; and

[128] FIG. 10 is a cross-sectional view illustrating an active matrix organic electroluminescent display device according to a fifth exemplary embodiment of the present invention.

[129]

Best Mode for Carrying Out the Invention

[130] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[131] Hereinafter, the present invention will be described more fully with reference to the accompanying drawings, in which exemplary embodiments thereof are shown.

[132]

[133] First Embodiment

[134] FIG. 5 is a cross-sectional view illustrating an organic light emitting transistor according to a first exemplary embodiment of the present invention; [135] Referring to FIG. 5, the reference number 111 designates a substrate, 111 designates a lower electrode acting as a source (or drain) electrode, 113 designates insulating films, 114 designates a first gate electrode, 115 designates a second gate electrode, 116 designates an organic semiconductor thin film layer, 117 designates an upper electrode acting as a drain (or a source) electrode, and 118 designates nano-particles or nano- lines.

[136] More specifically, as shown in FIG. 5, the lower electrode 112 acting as a source (or drain) electrode is layered in a predetermined pattern on the upper surface of the substrate 111, the insulating films 113 are formed and then patterned on both upper edges of the lower electrode 112, and the first and second gate electrodes 114 and 115 are formed on the insulating films 113. The organic semiconductor thin film layer 116 is coated on a portion of the lower electrode 112, which is not covered with the first and second electrodes 114 and 115 and the insulating films 113, and the upper electrode 117 acting as a drain (or source) electrode is formed on the organic semiconductor thin layer 116.

[137] The nano-particles or nano-lines 118 can be selectively inserted into the organic semiconductor thin film layer 116 adjacent to the lower electrode 112 to lower a voltage between the first gate electrode 114 and the second gate electrode 115. The nano-particles or nano-lines 118 can be made of various materials such as organic material, inorganic material and metal.

[138] Below, a description will be given of the operating principle of the organic light emitting transistor. When the organic semiconductor film layer 116 in contact with the lower electrode 112 acts as a hole injection layer, holes cannot be injected even if a voltage is applied to the upper and lower electrodes 117 and 112.This is because the ionization potential of a portion of the organic semiconductor film layer 116 in contact with the lower electrode 112 is greater than the work function of the lower electrode 112.However, when a voltage is applied to the first and second gate electrodes 114 and 115, the portion of the organic semiconductor film layer 116 in contact with the lower electrode 112 is electrically doped to lower its ionization potential so that holes are injected from the lower electrode 112 into the organic semiconductor film layer to emit light.

[139] An alternative inverted structure can also be provided, in which the lower electrode 112 is used as an electron injection electrode, so that the organic semiconductor film layer 116 operates as an electron injection layer and the upper electrode 117 operates as a hole injection layer.

[140] Now, a description will be given of a method of manufacturing the double-gate type organic light emitting transistor of the present invention.

[141] First, the lower electrode 112 is layered in a predetermined pattern on the upper surface of the substrate 111.

[142] The insulating films 113 are formed and then patterned on both upper edges of the lower electrode 112, which acts as a source (or drain) electrode, and the first or second gate electrode 114 or 115 is layered on the insulating films 113. The organic semiconductor thin film layer 116 is coated on a portion of the lower electrode 112, which is not covered with the first and second gate electrodes 114 and 115 and the insulating films 113, and the upper electrode 117 acting as a drain (or source) electrode is formed on the organic semiconductor thin film layer 116.

[143] Here, the substrate 111 may be implemented with a transparent substrate made up of a transparent material such as glass, metal, plastic, ceramics and silicon (Si). The lower electrode 112 may be formed by depositing a conductive material on the upper surface of the substrate 111, followed by lithography, or by a vacuum deposition or spin coating.

[144] The organic light emitting transistor of the present invention is very economic owing to a simple structure and a simple process. Especially, the organic light emitting transistor has an advantage of being able to control electron mobility since the channel width between the upper electrodes can be properly adjusted when the upper electrodes are being formed.

[145]

[146] Second Embodiment

[147] FIG. 6 is a cross-sectional view illustrating an organic light emitting transistor according to a second exemplary embodiment of the present invention.

[148] Referring to FIG. 6, the reference number 121 designates a substrate, 122 designates a lower electrode acting as a source (or drain) electrode, 123 designates insulating films, 124 designates a lower first gate electrode, 125 designates a lower second gate electrode, 126 designates an upper first gate electrode, 127 designates an upper second gate electrode, 128 designates an organic semiconductor thin film layer, 129 designates an upper electrode acting as a drain (or a source) electrode, 102a designates upper nano-particles or nano-lines, and 102b designates lower nano-particles or nano-lines.

[149] More specifically, as shown in FIG. 6, the lower electrode 122 acting as a source (or drain) electrode is layered in a predetermined pattern on the upper surface of the substrate 121, the insulating films 123 are formed and then patterned on both upper edges of the lower electrode 122, and the lower first and second gate electrodes 124 and 125 are formed on the insulating films 123. The organic semiconductor thin film layer 128 is coated on a portion of the lower electrode 122, which is not covered with the lower first and second electrodes 124 and 125 and the insulating films 123, and the upper first and second gate electrodes 126 and 127 and the upper electrode 129 acting as a drain (or source) electrode are formed on the organic semiconductor thin layer 128.

[150] The upper and lower nano-particles or nano-lines 102a and 102b can be selectively inserted into the organic semiconductor thin film layer 128 adjacent to the lower electrode 122 to lower a voltage between the upper or lower first gate electrode 124 or 126 and the upper or lower second gate electrode 125 or 127. The nano-particles or nano-lines 102a and 102b can be made of various materials such as organic material, inorganic material and metal.

[151] The upper gate electrodes 126 and 127 or the lower gate electrodes 124 and 125 can be simultaneously or separately controlled.

[152] Below, a description will be given of the operating principle of the stacked double- gate type organic light emitting transistor. When the organic semiconductor film layer 128 in contact with the lower electrode 122 acts as a hole injection layer, holes cannot be injected even if a voltage is applied to the upper and lower electrodes 127 and 122.This is because the ionization potential of a portion of the organic semiconductor film layer 128 in contact with the lower electrode 122 is greater than the work function of the lower electrode 122.However, when a voltage is applied to the lower first and second gate electrodes 124 and 125, the portion of the organic semiconductor film layer 128 in contact with the lower electrode 122 is electrically doped to lower its ionization potential so that holes can be injected from the lower electrode 122 to the organic semiconductor thin film layer 128 or its injection can be controlled. Further, a portion of the organic semiconductor thin film layer 128 in contact with the upper electrode 129 is also electrically doped by a voltage applied between the upper first and second gate electrodes 126 and 127 thereby to emit light by electron injection or control.

[153] An alternative inverted structure can also be provided, in which the lower electrode 122 is used as an electron injection electrode, so that the organic semiconductor film layer 126 operates as an electron injection layer and the upper electrode 127 operates as a hole injection layer.

[154] Now, a description will be given of a method of manufacturing the stacked double- gate type organic light emitting transistor of the present invention.

[155] First, the lower electrode 122 is layered in a predetermined pattern on the upper surface of the substrate 121.

[156] The insulating films 123 are formed and then patterned on both upper edges of the lower electrode 122, which acts as a source (or drain) electrode, and the lower first or second gate electrode 124 or 125 is layered on the insulating films 123. The organic semiconductor thin film layer 128 is coated on a portion of the lower electrode 122, which is not covered with the first and second gate electrodes 124 and 125 and the insulating films 123, and the upper first and second gate electrodes 126 and 127 the upper electrode 127 acting as a drain (or source) electrode are formed on the organic semiconductor thin film layer 126.

[157] Here, the substrate 121 may be implemented with a transparent substrate made up of a transparent material such as glass, metal, plastic, ceramics and silicon (Si). The lower electrode 122 may be formed by depositing a conductive material on the upper surface of the substrate 121, followed by lithography, or by a vacuum deposition or spin coating process.

[158] The organic light emitting transistor of the present invention is very economic owing to a simple structure and a simple process. Especially, the organic light emitting transistor has an advantage of being able to control electron mobility since the channel width between the upper electrodes can be properly adjusted when the upper electrodes are being formed.

[159]

[160] Third Embodiment

[161] FIG. 7 is a cross-sectional view illustrating an organic light emitting transistor according to a third exemplary embodiment of the present invention;

[162] Referring to FIG. 7, the reference number 131 designates a substrate, 132 designates a lower electrode double-used as a gate and an anode of a light emitting part of the transistor, 133 designates an insulating layer, 134 designates an organic semiconductor light emitting layer, 135 designates an upper source electrode, and 136 designates an upper drain electrode double-used as a cathode of the light emitting part.

[163] More specifically, as shown in FIG. 7, the lower electrode 132 is formed in a predetermined pattern on the upper surface of the substrate 131, and the organic semiconductor thin film layer 134 and the insulating layer 133 are formed on the lower electrode 132.A portion of the organic semiconductor thin film layer 134 extends to the upper surface of the insulating layer 133 to coat the same. The source electrode 135 is formed on the portion of the organic semiconductor thin film layer 134 coating the insulating layer 133, and the upper drain layer 136 is formed on another portion of the organic semiconductor thin film layer 134, spaced apart from the upper drain electrode 136 at a predetermined interval.

[164] Below, a description will be given of the operating principle of the organic light emitting transistor having a directly shared-electrode structure. First, when a voltage is applied to the lower electrode 132, an electron channel or a hole channel is formed in the portion of the organic semiconductor thin film layer 134 in contact with the insulating layer 133 so that electrons can flow from the upper source electrode 135 to the upper drain electrode 136.As a result, light is emitted from between the upper drain electrode 136 and the lower electrode 132.

[165] Now, a description will be given of a method of manufacturing the organic light emitting transistor according to the third embodiment of the present invention, which is constructed as above.

[166] First, the lower electrode 132 is layered in a predetermined pattern on the upper surface of the substrate 131.

[167] The insulating layer 133 is formed and then patterned on a portion of the lower electrode 132 acting as a gate and an anode or cathode of the transistor, and the organic semiconductor thin film layer 134 is coated on the insulating layer 133.The upper source electrode 135 is formed on a portion of the organic semiconductor thin film layer 134 layered on the insulating layer 133, and the upper drain electrode 136 is formed on the organic semiconductor thin film layer 134, in a position spaced apart from the upper source electrode 135 at a predetermined interval.

[168] Here, the substrate 131 may be implemented with a transparent substrate made up of a transparent material such as glass, metal, plastic, ceramics and silicon (Si). The lower electrode 132 may be formed by depositing a conductive material on the upper surface of the substrate 131, followed by lithography, or by a vacuum deposition or spin coating process.

[169] The upper drain electrode 136 acts as a cathode or anode of the light emitting part, and the lower electrode 132 acts not only as an anode or cathode of the light emitting part but also as a gate electrode of a drive part (transistor).

[170] FIG. 8 is a cross-sectional view illustrating an alternative to the organic light emitting transistor according to the third exemplary embodiment of the present invention.

[171] Referring to FIG. 8, the organic semiconductor thin film layer 134 and the insulating layer 133 are sequentially layered under the upper drain electrode 136, and the upper source electrode 135 is formed in a position spaced apart from the upper drain electrode 136 at a predetermined interval.

[172] The upper source electrode 135 acts as a cathode or anode of the light emitting part as well as a source electrode of the drive part (transistor).When a voltage is applied to the lower electrode 132 acting as an anode or cathode of the light emitting part as well as a gate electrode of the drive part, an electron channel or a hole channel is formed in a portion of the organic semiconductor thin film layer 134 in contact with the insulating layer 133 so that electrons flow from the upper drain electrode 136 to the upper source electrode 135.As a result, light emits from between the upper source electrode 135 and the lower electrode 132.

[173] The organic light emitting transistor of the present invention having a directly shared-electrode structure is very economic owing to a simple structure and a simple process. Especially, the organic light emitting transistor has an advantage of being able to control electron mobility since the channel width between the upper electrodes can be properly adjusted when the upper electrodes are being formed. [174]

[175] Fourth Embodiment

[176] FIG. 9 is a cross-sectional view illustrating an active matrix organic electroluminescent display device according to a fourth exemplary embodiment of the present invention.

[177] In FIG. 9, the reference number 141 designates a substrate, 142 designates a source electrode of an organic thin-film transistor (OTFT), 143 designates a drain electrode of the OTFT or a cathode (or an anode) of an organic light emitting device (OLED), 144 designates an organic thin film layer, 145 designates a gate dielectric layer of the OTFT, 146 designates an electron injection layer of the OLED, 147 designates a gate metal electrode of the OTFT, and 148 designates a second electrode of the OLED acting as a cathode (or an anode).

[178] In the active matrix organic electroluminescent display device as shown in FIG. 9, the source electrode 142 of the OTFT is formed in a predetermined pattern on the upper surface of the substrate 141, the drain electrode 143 of the OTFT is formed on the upper surface of the substrate 141 at a predetermined interval from the source electrode 142 and is also used as a first electrode of the OLED. The organic thin film layer 144 is formed on the substrate 141 to sufficiently cover the source electrode 142 and the drain electrode 143 of the OTFT. The gate electrode 147 of the OTFT and the second electrode 148 of the OLED are formed in a predetermined pattern on the organic thin film layer 144.The gate dielectric layer 145 of the OTFT is formed between the gate electrode 147 of the OTFT and the organic thin film layer 144.The electron injection layer 146 of the OLED is formed between the second electrode 148 of the OLED and the organic thin film layer 144.

[179] Now, a description will be given of a method of manufacturing the active matrix organic light emitting display device (AMOLED) according to the present invention, in which an OTFT is incorporated.

[180] First, the drain electrode 143 of the OTFT, also used as the first electrode of the OLED, and the source electrode 142 of the OTFT are formed in a predetermined pattern on the upper surface of the substrate 141.

[181] Here, the substrate 141 may be implemented with a transparent substrate made up of a transparent material such as glass, metal, plastic, ceramics and silicon (Si). The drain electrode 143 of the OTFT and the source electrode 142 of the OTFT may be formed by depositing a conductive material on the upper surface of the substrate 141, followed by lithography, or by a vacuum deposition or spin coating process.

[182] Then, the organic thin film layer 144 is formed on the substrate 141 at such a level to sufficiently cover the source and drain electrodes 142 and 143 of the OTFT. Preferably, the organic thin film layer 144 may be formed of a single layer or multi- layers.

[183] The dielectric layers 145 and 146 are then formed on the organic thin film layer 144, followed by forming the conductive layers (corresponding to 147 and 148) thereon.

[184] The conductive layers and the dielectric layers are then patterned into a predetermined form.

[185] Next, the conductive layers and the dielectric layers are etched to expose the organic dielectric thin film layer 144, thereby forming a contact hole. An element isolation part 149 is then formed in the contact hole to separate the upper area into two regions, which are isolated from each other. Portions of the dielectric and conductive layers on one side of the contact hole form the gate dielectric layer 145 and the gate electrode 147 of the OTFT, respectively, and the other portions of the dielectric and conductive layers on the other side of the contact hole form the electron injection layer 146 and the second electrode 148 of the OLED, respectively.

[186] Here, the first electrode of the OLED may form an anode and the second electrode of the OLED may form a cathode and vice versa.

[187] Since the drain electrode 143 of the OTFT is also used as the first electrode of the OLED according to the present invention, when the upper gate electrode 147 of the OTFT is turned on, currents flow from the source electrode 142 of the OTFT to the drain electrode 143, thereby causing the OLED to emit light.

[188] In particular, since the gate electrode 147 of the OTFT is deposited simultaneously with the second electrode 148 of the OLED, the OTFT and the OLED can be manufactured in one- step, which is economically advantageous.

[189] Further, the amount of currents flowing from the source electrode to the drain electrode can be previously adjusted to an amount necessary in a lithography process by properly adjusting the interval between the drain electrode 143 of the OTFT and the source electrode 142 of the OTFT in the lithography process.

[190] Accordingly, this embodiment is very economical compared to a conventional separated structure and has an advantage capable of maximizing opening ratio.

[191]

[192] Fifth Embodiment

[193] FIG. 10 is a cross-sectional view illustrating an organic light emitting display device (OLED) according to a fifth exemplary embodiment of the present invention.

[194] Referring to FIG. 10, the reference number 156 designates a substrate, 152 designates a source electrode of an OTFT, 153 designates a drain electrode of the OTFT and an anode (or a cathode) of the OLED, 155 designates an organic thin film layer made up of a single layer or multi-layers, 151 designates a gate metal electrode of the OTFT, 154 designates a second electrode of the OLED acting as a cathode (or an anode), 157 designates an upper electrode of an organic capacitor, 158 designates a lower electrode of the organic capacitor, and 159 designates an organic/inorganic doping layer, which is formed selectively.

[195] In the OLED of the present invention of the present invention as shown in FIG. 10, the source electrode 152 of the OTFT is formed in a predetermined pattern on the upper surface of the substrate 156, the drain electrode 153 of the OTFT is formed on the upper surface of the substrate 156 at a predetermined interval from the source electrode 152 and is also used as a first electrode of the OLED. The organic thin film layer 155 is formed on the substrate 156 to sufficiently cover the source electrode 152 and the drain electrode 153 of the OTFT. The gate electrode 151 of the OTFT is formed on the organic thin film layer 155, spaced apart from the second electrode 154 of the OLED at a predetermined interval. The upper electrode 157 of the organic capacitor is formed on the organic thin film layer 155, spaced apart from the second electrode 154 of the OLED at a predetermined interval, and the lower electrode 158 of the organic capacitor is formed on the substrate 156, spaced apart from the drain electrode 153.

[196] The organic/inorganic doping layer 159 may be selectively formed on the lower electrode of the organic capacitor, surrounded by the organic thin film layer 155.

[197] Now, a description will be given of a method of manufacturing the OLED according to the present invention, which is constructed as above.

[198] First, the drain electrode 153 of the OTFT, also used as the first electrode of the OLED, the source electrode 152 of the OTFT and the lower electrode 158 of the organic capacitor are formed in a predetermined pattern on the upper surface of the substrate 156.

[199] Here, the substrate 156 may be implemented with a transparent substrate made up of a transparent material such as glass, metal, plastic, ceramics and silicon (Si). The drain electrode 153 of the OTFT, the source electrode 152 of the OTFT and the lower electrode 158 of the organic capacitor may be formed by depositing a conductive material on the upper surface of the substrate 156, followed by lithography, or by a vacuum deposition or spin coating process.

[200] Then, the organic thin film layer 155 is formed on the substrate 156 at such a level to sufficiently cover the source and drain electrodes 152 and 153 of the OTFT and the lower electrode 158 of the organic capacitor. Preferably, the organic thin film layer 155 may be formed of a single layer or multi-layers.

[201] In the forming of the organic thin film layer 155, an organic/inorganic doping layer may be layered on the lower electrode 158 of the organic capacitor.

[202] Then, a dielectric layer is formed on the organic thin film layer 155, and a conductive layer is formed on the dielectric layer.

[203] The conductive layer and the dielectric layer are then patterned into a predetermined form.

[204] Next, the conductive layer and the dielectric layer are etched to expose the organic dielectric thin film layer 155, thereby forming contact holes.

[205] Portions of the dielectric and conductive layers on one side of the contact holes form a gate dielectric layer (not shown) and the gate electrode 151 of the OTFT, respectively, and the other portions of the dielectric and conductive layers on the other side of the contact holes form an electron injection layer (not shown) and the second electrode 154 of the OLED, respectively. Further, the upper electrode 157 of the organic capacitor is formed on the organic thin film layer 155, spaced apart from the second electrode 154 at a predetermined interval.

[206] Here, the first electrode of the OLED may form an anode and the second electrode of the OLED may form a cathode and vice versa.

[207] Since the drain electrode 153 of the OTFT is also used as the first electrode of the OLED according to the present invention, when the upper gate electrode 151 of the OTFT is turned on, currents flow from the source electrode 152 of the OTFT to the drain electrode 153, thereby causing the OLED to emit light. Further, an OCAP is formed on the same substrate as a charge storage device, which stores electric charge in order to supply currents to the OLED in a state where a switching transistor is turned off.

[208] In particular, since the gate electrode 151 of the OTFT, the second electrode 154 of the OLED and the upper electrode 157 of the OCAP are simultaneously deposited, the OTFT, the OCAP the OLED can be manufactured in one-step, which is economically advantageous.

[209] Further, since the size ratio of the OTFT, the OLED and the OCAP can be properly changed, this embodiment is very economical compared to a conventional separated structure and has an advantage capable of adjusting the opening ratio.

[210]

[211] While the present invention has been described with reference to the particular illustrative embodiments and the accompanying drawings, it is not to be limited thereto but will be defined by the appended claims. It is to be appreciated that those skilled in the art can substitute, change or modify the embodiments in various forms without departing from the scope and spirit of the present invention.

Claims

[1] An organic light emitting transistor comprising: a lower electrode formed in a predetermined pattern on one side of a substrate; a pair of insulating films formed on upper surface portions of the lower electrode, spaced apart from each other; first and second gate electrodes layered on upper surface portions of the insulating films; an organic semiconductor thin film layer coated on an upper surface of a portion of the lower electrode, which is not coated with any one of the first and second gate electrodes and the insulating thin films; and an upper electrode formed on an upper surface portion the semiconductor thin film layer.

[2] The organic light emitting transistor according to claim 1, wherein the lower electrode acts as a source or drain electrode.

[3] The organic light emitting transistor according to claim 1, wherein the upper electrode acts as a drain or source electrode.

[4] The organic light emitting transistor according to claim 1, further comprising nano-particles or nano-lines selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[5] The organic light emitting transistor according to claim 4, wherein the na no- particles or nano-lines are made of one selected from an organic material, an inorganic material and metal.

[6] The organic light emitting transistor according to claim 1, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[7] The organic light emitting transistor according to claim 1, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to increase ionization potential so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[8] The organic light emitting transistor according to claim 1, wherein the substrate comprises a transparent substrate.

[9] The organic light emitting transistor according to claim 8, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[10] A method of manufacturing an organic light emitting transistor, comprising:

(a) layering a lower electrode in a predetermined pattern on one side of a substrate;

(b) forming insulating films on both upper edges of the lower electrode and patterning the insulating films;

(c) layering first and second gate electrodes on upper surface portions of the lower electrode, the first gate electrode spaced apart from the second gate electrode at a predetermined interval;

(d) coating an organic semiconductor thin film layer on an upper surface of a portion of the lower electrode, which is not coated with any one of the first and second electrodes and the insulating films; and

(e) forming an upper electrode on an upper surface portion of the organic semiconductor thin film layer.

[11] The method according to claim 10, wherein the lower electrode acts as a source or drain electrode.

[12] The method according to claim 10, wherein the upper electrode acts as a drain or source electrode.

[13] The method according to claim 10, wherein nano-particles or nano-lines are selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[14] The method according to claim 13, wherein the nano-particles or nano-lines are made of one selected from an organic material, an inorganic material and metal.

[15] The method according to claim 10, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[16] The method according to claim 10, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the first and second gate electrodes to increase ionization potential so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[17] The method according to claim 10, wherein the substrate comprises a transparent substrate.

[18] The method according to claim 17, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[19] An organic light emitting transistor, comprising: a lower electrode formed in a predetermined pattern on one side of a substrate; a pair of insulating films formed on upper surface portions of the lower electrode, spaced apart from each other; lower first and second gate electrodes layered on upper surface portions of the insulating films; an organic semiconductor thin film layer coated on an upper surface of a portion of the lower electrode, which is not coated with any one of the lower first and second gate electrodes and the insulating thin films; and upper first and second gate electrodes and an upper electrode formed on upper surface portions the semiconductor thin film layer.

[20] The organic light emitting transistor according to claim 19, wherein the lower electrode acts as a source or drain electrode.

[21] The organic light emitting transistor according to claim 19, wherein the lower electrode acts as a drain or source electrode.

[22] The organic light emitting transistor according to claim 19, further comprising upper or lower nano-particles or nano-lines selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[23] The organic light emitting transistor according to claim 22, wherein the nano- particles or nano-lines are made of one selected from an organic material, an inorganic material and metal.

[24] The organic light emitting transistor according to claim 19, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the lower first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer, and another portion of the organic semiconductor thin film layer in contact with the upper electrode is electrically doped by a voltage applied between the upper first and second gate electrodes so that electrons are injected so as to emit light.

[25] The organic light emitting transistor according to claim 19, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped to increase ionization potential by a voltage applied to the first and second gate electrodes so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[26] The organic light emitting transistor according to claim 19, wherein the substrate comprises a transparent substrate.

[27] The organic light emitting transistor according to claim 26, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[28] The organic light emitting transistor according to claim 19, wherein the upper first and second gate electrodes and the lower first and second gate electrodes are simultaneously or separately controlled.

[29] The organic light emitting transistor according to claim 19, wherein the upper first and second gate electrodes and the upper electrode are formed simultaneously.

[30] A method of manufacturing an organic light emitting transistor, comprising:

(c) layering lower first and second gate electrodes on upper surface portions of the lower electrode, the lower first gate electrode spaced apart from the second gate electrode at a predetermined interval;

(d) coating an organic semiconductor thin film layer on an upper surface of a portion of the lower electrode, which is not coated with any one of the lower first and second electrodes and the insulating films; and

(e) forming upper first and second gate electrodes and an upper electrode on an upper surface portion of the organic semiconductor thin film layer.

[31] The method according to claim 30, wherein the lower electrode acts as a source or drain electrode.

[32] The method according to claim 30, wherein the upper electrode acts as a drain or source electrode.

[33] The method according to claim 30, wherein upper or lower nano-particles or nano-lines are selectively inserted into the organic semiconductor thin film layer adjacent to the lower electrode.

[34] The method according to claim 33, wherein the nano-particles or nano-lines are made of one selected from an organic material, an inorganic material and metal.

[35] The method according to claim 30, wherein the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, and wherein a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped by a voltage applied to the lower first and second gate electrodes to lower ionization potential so that holes are injected from the lower electrode into the organic semiconductor thin film layer, and another portion of the organic semiconductor thin film layer in contact with the upper electrode is electrically doped by a voltage applied between the upper first and second gate electrodes so that electrons are injected so as to emit light.

[36] The method according to claim 30, wherein, the organic semiconductor thin film layer in contact with the lower electrode comprises a hole injection layer, a portion of the organic semiconductor thin film layer in contact with the lower electrode is electrically doped to increase ionization potential by a voltage applied to the first and second gate electrodes so that electrons are injected from the lower electrode into the organic semiconductor thin film layer so as to emit light.

[37] The method according to claim 30, wherein the substrate comprises a transparent substrate.

[38] The method according to claim 37, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[39] The method according to claim 30, wherein the upper first and second gate electrodes and the lower first and second gate electrodes are simultaneously or separately controlled.

[40] The method according to claim 30, wherein the upper first and second gate electrodes and the upper electrode are formed simultaneously.

[41] An organic light emitting transistor comprising: a lower electrode formed in a predetermined pattern on one side of a substrate; an insulating film formed on an upper surface portion of the lower electrode; an organic semiconductor thin film layer covering upper surfaces of the lower electrode and the insulating film; an upper drain electrode formed on an upper surface portion of the organic semiconductor thin film layer coated on the insulating film; and an upper source electrode formed on another upper surface portion of the organic semiconductor thin film layer and, spaced apart from the upper drain electrode at a predetermined interval.

[42] The organic light emitting transistor according to claim 41, wherein the upper drain electrode acts as a cathode or anode of a light emitting part.

[43] An organic light emitting transistor comprising: a lower electrode formed in a predetermined pattern on one side of a substrate; an insulating film formed on an upper surface portion of the lower electrode; an organic semiconductor thin film layer covering upper surfaces of the lower electrode and the insulating film; an upper source electrode formed on an upper surface portion of the organic semiconductor thin film layer coated on the insulating film; and an upper drain electrode formed on another upper surface portion of the organic semiconductor thin film layer, spaced apart from the upper source electrode at a predetermined interval.

[44] The organic light emitting transistor according to claim 43, wherein the upper source electrode acts as a cathode or anode of a light emitting part.

[45] The organic light emitting transistor according to claim 41 or 43, wherein the lower electrode acts as an anode or cathode of the light emitting part as well as a gate electrode of a drive part.

[46] The organic light emitting transistor according to claim 41 or 43, wherein an electron channel or a hole channel is formed in the organic semiconductor thin film in contact with the insulating film by a voltage applied to the lower electrode.

[47] The organic light emitting transistor according to claim 41 or 43, comprising a directly- shared electrode structure, in which electron mobility of a device is controlled by adjusting a channel width of the upper electrodes.

[48] The organic light emitting transistor according to claim 41 or 43, wherein the substrate comprises a transparent substrate.

[49] The organic light emitting transistor according to claim 48, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[50] A method of manufacturing an organic light emitting transistor, comprising:

(b) forming an insulating film on an upper surface portion of the lower electrode and patterning the insulating film;

(c) coating an organic semiconductor thin film layer on an upper surface of the insulating film;

(d) forming an upper source electrode on an upper surface portion of the organic semiconductor thin film layer coated on the insulating layer; and

(e) forming an upper drain electrode in a position spaced apart from the upper source electrode at a predetermined interval.

[51] The method according to claim 50, wherein the upper drain electrode acts as a cathode or anode of a light emitting part.

[52] A method of manufacturing an organic light emitting transistor, comprising:

(d) forming an upper drain electrode on an upper surface portion of the organic semiconductor thin film layer coated on the insulating layer; and

(e) forming an upper source electrode in a position spaced apart from the upper source electrode at a predetermined interval.

[53] The method according to claim 52, wherein the upper drain electrode acts as a cathode or anode of a light emitting part.

[54] The method according to claim 50 or 52, wherein the lower electrode acts as an anode or cathode of the light emitting part as well as a gate electrode of a drive part.

[55] The method according to claim 50 or 52, wherein an electron channel or a hole channel is formed in the organic semiconductor thin film in contact with the insulating film by a voltage applied to the lower electrode.

[56] The method according to claim 50 or 52, wherein a directly- shared electrode structure controls electron mobility of a device by adjusting a channel width of the upper electrodes.

[57] The method according to claim 50 or 52, wherein the substrate comprises a transparent substrate.

[58] The method according to claim 57, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[59] An active matrix organic light emitting display device, in which an organic thin film transistor is embedded, comprising: a source electrode of the organic thin film transistor formed in a predetermined pattern on one side of a substrate; a drain electrode of the organic thin film transistor formed in a predetermined pattern on the one side of the substrate and spaced apart from the source electrode at a predetermined interval, the drain electrode also used as a first electrode of the organic light emitting display device; an organic thin film layer formed on the substrate to cover the source and drain electrodes of the organic thin film transistor; a gate electrode of the organic thin film transistor formed in a predetermined pattern on the organic thin film layer; a second electrode of the organic light emitting display device formed in a predetermined pattern on the organic thin film layer; a gate dielectric layer of the organic thin film transistor formed between the gate electrode of the organic thin film transistor and the organic thin film layer; and an electron injection layer of the organic light emitting layer formed between the second electrode of the organic light emitting display device and the organic thin film layer.

[60] The active matrix organic light emitting display device according to claim 59, wherein an interval between the drain electrode and the source electrode of the organic thin film transistor is adjusted by lithography to control currents flowing from the source electrode to the drain electrode at a predetermined amount.

[61] The active matrix organic light emitting display device according to claim 59, wherein the gate electrode of the organic thin film transistor is deposited together with the second electrode of the organic light emitting display device, whereby the organic light emitting display device and the organic thin film transistor are manufactured in one process.

[62] The active matrix organic light emitting display device according to claim 59, wherein the first electrode of the organic light emitting display device comprises an anode, and the second electrode of the organic light emitting display device comprises a cathode.

[63] The active matrix organic light emitting display device according to claim 59, wherein the first electrode of the organic light emitting display device comprises a cathode, and the second electrode of the organic light emitting display device comprises an anode.

[64] A method of manufacturing an active matrix organic light emitting display device, in which an organic thin film transistor is embedded, the method comprising:

(a) forming a drain electrode and a source electrode of the organic thin film transistor in a predetermined pattern on one side of a substrate, the drain electrode of the organic light emitting display device also used as a first electrode of the organic light emitting display device;

(b) forming an organic thin film layer on the substrate to cover the source electrode and the drain electrode of the organic thin film transistor;

(c) forming a dielectric layer and a conductive layer sequentially on the organic thin film layer; (d) patterning the conductive layer and the dielectric layer in a predetermined form; and

(e) forming a contact hole by etching the conductive layer and the dielectric layer to expose the organic thin film layer so that the dielectric layer and the conductive layer on one side of the contact hole form a gate dielectric layer and a gate electrode of the organic thin film transistor and the dielectric layer and the conductive layer on another side of the contact hole form an electron injection layer and a second electrode of the organic light emitting display device.

[65] The method according to claim 64, wherein an interval between the drain electrode and the source electrode of the organic thin film transistor is adjusted by lithography to control currents flowing from the source electrode to the drain electrode at a predetermined amount.

[66] The method according to claim 64, wherein the step (a) of forming a drain electrode and a source electrode of the organic thin film transistor comprises depositing a conductive material on the one side of the substrate, followed by lithography, to form the drain electrode and the source electrode.

[67] The method according to claim 64, wherein the step (a) of forming a drain electrode and a source electrode of the organic thin film transistor comprises performing vacuum deposition or spin coating to form the drain electrode and the source electrode.

[68] The method according to claim 64, wherein the gate electrode of the organic thin film transistor is deposited together with the second electrode of the organic light emitting display device, whereby the organic light emitting display device and the organic thin film transistor are manufactured in one process.

[69] The method according to claim 64, wherein the first electrode of the organic light emitting display device comprises an anode, and the second electrode of the organic light emitting display device comprises a cathode.

[70] The method according to claim 64, wherein the first electrode of the organic light emitting display device comprises a cathode, and the second electrode of the organic light emitting display device comprises an anode.

[71] The method according to claim 64, wherein the organic thin film layer comprises a single layer or multi-layers.

[72] The method according to claim 64, wherein the substrate comprises a transparent substrate.

[73] The method according to claim 64 or 72, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon.

[74] An active matrix organic light emitting display device, in which an organic thin film transistor and an organic capacitor are embedded, comprising: a source electrode of the organic thin film transistor formed in a predetermined pattern on one side of a substrate; a drain electrode of the organic thin film transistor formed in a predetermined pattern on the one side of the substrate and spaced apart from the source electrode at a predetermined interval, the drain electrode also used as a first electrode of the organic light emitting display device; a lower electrode of the organic capacitor formed on the one side of the substrate, spaced apart from the drain electrode at a predetermined interval; an organic thin film layer formed on the substrate to cover the source and drain electrodes of the organic thin film transistor and the lower electrode of the organic capacitor; and a gate electrode of the organic thin film transistor formed in a predetermined pattern on the organic thin film layer; a second electrode of the organic light emitting display device formed in a predetermined pattern on the organic thin film layer; and an upper electrode of the organic capacitor formed in a predetermined pattern on the organic thin film layer.

[75] The active matrix organic light emitting display device according to claim 74, wherein an opening ratio is maximized by adjusting size ratios of the organic thin film transistor, the organic light emitting display device and the organic capacitor.

[76] The active matrix organic light emitting display device according to claim 74, wherein the first electrode of the organic light emitting display device comprises an anode, and the second electrode of the organic light emitting display device comprises a cathode.

[77] The active matrix organic light emitting display device according to claim 74, wherein the first electrode of the organic light emitting display device comprises a cathode, and the second electrode of the organic light emitting display device comprises an anode.

[78] The active matrix organic light emitting display device according to claim 74, further comprising an organic/inorganic doping layer layered on an upper surface portion the lower electrode of the organic capacitor in forming of the organic thin film layer.

[79] A method of manufacturing an organic light emitting display device, in which an organic thin film transistor and an organic capacitor are embedded, the method comprising:

(a) forming a drain electrode and a source electrode of the organic thin film transistor and a lower electrode of the organic capacitor in a predetermined pattern on one side of a substrate, the drain electrode of the organic light emitting display device also used as a first electrode of the organic light emitting display device;

(b) forming an organic thin film layer on the substrate to cover the source electrode and the drain electrode of the organic thin film transistor and the lower electrode of the organic capacitor;

(c) forming a dielectric layer and a conductive layer sequentially on the organic thin film layer;

(d) patterning the conductive layer and the dielectric layer in a predetermined form; and

(e) forming a gate electrode and a second electrode of the organic thin film transistor and the upper electrode of the organic capacitor by etching the conductive layer and the dielectric layer to expose the organic thin film layer.

[80] The method according to claim 79, wherein an opening ratio is adjusted by changing size ratios of the organic thin film transistor, the organic light emitting display device and the organic capacitor. [81] The method according to claim 79, wherein the step (a) of forming a drain electrode and a source electrode of the organic thin film transistor comprises depositing a conductive material on the one side of the substrate, followed by lithography, to form the drain electrode and the source electrode. [82] The method according to claim 79, wherein the step (a) of forming a drain electrode and a source electrode of the organic thin film transistor comprises performing vacuum deposition or spin coating to form the drain electrode and the source electrode. [83] The method according to claim 79, wherein the first electrode of the organic light emitting display device comprises an anode, and the second electrode of the organic light emitting display device comprises a cathode. [84] The method according to claim 79, wherein the first electrode of the organic light emitting display device comprises a cathode, and the second electrode of the organic light emitting display device comprises an anode. [85] The method according to claim 79, wherein the organic thin film layer comprises a single layer or multi-layers. [86] The method according to claim 79, wherein the substrate comprises a transparent substrate. [87] The method according to claim 79 or 86, wherein the substrate comprises one selected from the group consisting of glass, metal, plastic, ceramic and silicon. [88] The method according to claim 79, wherein an organic/inorganic doping layer is formed to be layered on an upper surface portion of the lower electrode of the organic capacitor in the forming of the organic thin film layer.