Organic electroluminescent device and manufacturing method thereof

Description

BACKGROUND 1. Field of the Disclosure

[0001] The present application relates to an organic electroluminescence device. More particularly, the present application relates to an organic electroluminescence device adapted to secure reliability against light, and to a fabrication method thereof.2. Description of the Related Art

[0002] An organic electroluminescence device is called as an organic light emitting display (OLED) device. The organic electroluminescence device emits light by forming excitons through re-combination of electrons and electric-holes, which are injected from an electron injection electrode and an electric-hole injection electrode into an organic light emission layer, and transitioning the excitons from an excited state to a ground state.

[0003] As such, the organic electroluminescence device has a self-luminous property. In other words, the organic electroluminescence device does not require any separated light source, unlike a liquid crystal display device. In accordance therewith, the organic electroluminescence device can reduce thickness and weight. Also, the organic electroluminescence device has superior features of low power consumption, high brightness, high-speed response and so on. Therefore, the organic electroluminescence device attracts public attention as a next generation display device of a mobile appliance. Moreover, a procedure of fabricating the organic electroluminescence device is simple. As such, fabricating cost of the organic electroluminescence device is reduced larger than that of the existing liquid crystal display device.

[0004] In order to realize a variety of colors, a color filter mode using white light and color filters, a color changing mode using blue light and a color change medium, a three color independent pixel mode using red, green and blue organic light emission materials and so on are being applied to the organic electroluminescence devices. The organic electroluminescence device using white light and color filters is called as a white OLED device.

[0005] The organic electroluminescence device allows light generated in the organic light emission layer to be emitted toward an electrode with a high transmittance among first and second electrodes. Such organic electroluminescence devices are classified into a top emission mode and a bottom emission mode.

[0006] Fig. 1A is a cross-sectional view showing an organic electroluminescence device of the related art. In detail, Fig. 1A is a cross-sectional view showing a white OLED device of a bottom emission mode according to the related art. Fig. 1B is an enlarged view largely showing a region A in Fig. 1A.

[0007] Referring to Fig. 1A, the organic electroluminescence device 10 of the related art includes a first substrate 11 provided with a thin film transistor array 14 and an organic light emission layer 44, and a second substrate (not shown) facing the first substrate 11. The organic electroluminescence device 10 is completed by combining the first substrate 11 and the second substrate (not shown) using a sealant.

[0008] In detail, the organic electroluminescence device includes the thin film transistor array 14 formed on the first substrate 11, a first electrode 42 independently patterned on the thin film transistor array 14 into pixels, the organic light emission layer 44 formed on the first electrode 42, and a second electrode 45 formed on the entire surface of the organic light emission layer 44. The thin film transistor array 14 is configured with a plurality of thin film transistors which includes a driving thin film transistor T and is formed on the first substrate 11. The driving thin film transistor T included in the thin film transistor array can become any one of an edge stopper structure and a coplanar structure.

[0009] The driving thin film transistor T can be formed in the coplanar structure as shown in Fig. 1B. The driving thin film transistor T of the coplanar structure includes: a buffer layer 12 formed on the entire surface of the substrate 11; a semiconductor layer 20 formed on the buffer layer 12; a gate insulation film 21 and a gate electrode 22 sequentially formed on the central region of the semiconductor layer 20; a first insulation layer 23 formed on the entire surface of the substrate 11 provided with the gate insulation 21 and the gate electrode 22; source and drain electrodes 24a and 24b formed on the first insulation layer 23; and so on.

[0010] The semiconductor layer 20 is defined into an active domain 20' and source / drain domains 20a and 20b which are formed in both sides of the active domain 20'. The source and drain electrodes 24a and 24b are connected to the source and drain domains 20a and 20b of the semiconductor layer 20, respectively.

[0011] A second insulation layer 30 is formed on the entire surface of the substrate 11 provided with the source and drain electrodes 24a and 24b. The first electrode 42, the organic light emission layer 44 and so on are sequentially formed on the second insulation layer 30.

[0012] Referring to Figs. 1A and 1B, if the organic electroluminescence device is a white OLED device, the organic light emission layer 44 emits white light. In this case, red, green and blue color filters 31, 32 and 33 are formed between the second insulation layer 30 and the first electrode 42 in red, green and blue pixel regions. However, any color filter is not formed in a white pixel region.

[0013] If the organic electroluminescence device 10 is formed in the bottom emission mode, light emitted from the organic light emission layer 44 is radiated to the exterior through the first substrate 11. In this case, the second electrode 45 also performs a function of a reflective plate. The bottom emission mode forces the plurality of thin film transistors including the driving thin film transistor T to be easily exposed to light which is emitted from the organic light emission layer 44. More particularly, the white OLED device including the organic light emission layer formed on the entire surface of the substrate 11 forces the exposure of the thin film transistors to increase.

[0014] Meanwhile, IGZO (indium gallium zinc oxide) recently attracts public attention as a material of the semiconductor layer 20 of the thin film transistor. This results from the fact that IGZO has transparency and superior conductivity and is possible to use a low temperature process of below 300°C. However, IGZO enables atoms to exist at deep states near an electron band. Due to this, IGZO must be materially sensitive to light.

[0015] Moreover, IGZO with a high mobility is more sensitive to light because of having a narrow band gap. Actually, properties of IGZO are easy to deteriorate by light included in green and blue wavelength bands and by feeble light of about 500cd / m2.

[0016] Due to this, when IGZO is used in the organic electroluminescence device and more particularly in the white OLED device as a semiconductor material, reliability of the thin film transistor against light must largely deteriorate.

[0017] US 2005 / 0269942 A1 discloses an organic light emitting display apparatus having a thin film transistor consisting of gate electrode, a semiconductor layer, a source electrode and a drain electrode; a first electrode (pixel electrode); an organic light emitting layer formed on the first electrode; and a second electrode (counter electrode) formed on the organic light emission layer. Over the thin film transistor between the thin film transistor and the organic light emitting layer a light absorption layer is formed which shield the thin film transistor as well as the data line or the power supply line from light emitted from the OLED layer so that no additional light blocking layer is required between the different pixels of the display device. Here the light absorption layer formed by the red color filter layer and the green color filter layer or by all three-color filter layers is provided to reduce cross talk between the pixels.

[0018] US 2008 / 0024479 A1 discloses another organic electro-luminescent display device, the thin film transistors of which are provided with a light shielding layer formed by color filter layers. Further, a planarization layer is provided on the light shielding layers and on the color filters. A pixel electrode (anode) is formed on the planarization layer. Thereafter, a bank dielectric layer is formed and patterned so as to expose the pixel electrode through a pixel hole. Thereafter, an organic layer and a cathode layer are formed.

[0019] US 2002 / 0038998 A1 is concerned with a luminescent display device of active matrix drive type having thin film transistors and electroluminescent devices consisting of a pixel electrode and an electroluminescent layer and a counter electrode. The active layer of the thin film transistors is covered by a light-shielding gate insulating film. Further, between the substrate and the active layer of the thin film transistors a second light shielding layer and a buffer layer are provided.

[0020] US 2007 / 0090365 A1 is related to field-effect transistors including transparent oxide and light-shielding member and to displays using such transistors. The display comprises a thin film transistor consisting of an oxide semiconductor layer formed on a gate insulating layer and being in contact with source and drain electrodes and a gate; a first electrode (pixel electrode), an organic light emission layer, and a second electrode formed on the light emitting layer. Here a light shielding member is arranged under the thin film transistor. A light shielding layer is provided on the thin film transistor, i.e. between the thin film transistor and a pixel electrode. Here the oxide semiconductor layer of the thin is based on an IGZO structure.

[0021] US 2004 / 0012028 A1 is related to a multi-layered structure of an organic EL diode. In this structure, a gate insulating layer is formed on a buffer layer. A first insulating layer is formed on the gate insulating layer. An anode is formed on the first insulating layer. Second and third insulating layers commonly having an open portion are sequentially formed on the anode. An organic EL layer and a cathode are connected to the anode through the open portion. The anode is connected to a drain electrode of a TFT through an anode contact hole and the TFT is insulated from the organic EL layer by the third insulating layer.

[0022] US 2004 / 0080266 A1 is related to an active matrix organic electroluminescent display device that includes a substrate including a light emitting region having sub pixel regions, a plurality of switching elements on the substrate in the sub pixel regions, a first passivation layer covering the plurality of switching elements and having a plurality of first contact holes exposing the plurality of switching elements, a plurality of first electrodes on the first passivation layer, each first electrode connected to each switching element through each first contact hole, a second passivation layer on the plurality of first electrodes, the second passivation layer having a plurality of openings exposing the plurality of first electrodes and covering edge portions of the plurality of first electrodes, a plurality of organic electroluminescent layers on the second passivation layer, each organic electroluminescent layer contacting each first electrode through each opening, and a second electrode on the plurality of organic electroluminescent layers, wherein the first passivation layer is made of a first organic material having a planarized upper surface and the second passivation layer is made of a second organic material having a formation temperature lower than a formation temperature of inorganic materials.BRIEF SUMMARY

[0023] Accordingly, embodiments of the present application are directed to an organic electroluminescence device and a fabrication method thereof that substantially obviate one or more of problems due to the limitations and disadvantages of the related art.

[0024] The object of the present invention is to provide an organic electroluminescence device which is adapted to secure reliability against light by preventing deterioration of a thin film transistor due to light emitted from an organic light emission layer and due to moisture and alien substances, and a fabrication method thereof.

[0025] Also, the embodiments are to provide an organic electroluminescence device which is adapted to secure reliability against light by preventing deterioration of a thin film transistor due to external light, and a fabrication method thereof.

[0026] The above identified objects are solved by the features of the independent claims. Advantageous embodiments can be derived from the respective dependent claims.

[0027] An organic electroluminescence device includes: a thin film transistor; a first electrode connected to the thin film transistor; an organic light emission layer formed on the first electrode; a second electrode formed on the organic light emission layer; and a first light absorption layer formed over the thin film transistor between the thin film transistor and the organic light emission layer. The first light absorption layer is configured to shield light emitted from the organic light emission layer.

[0028] Also, the organic electroluminescence device further includes a second light absorption layer formed under the thin film transistor to prevent deterioration thereof due to external light.

[0029] Another organic electroluminescence device comprises a transistor array including a plurality of thin film transistors; an organic light emitting diode array including a plurality of organic light emitting diodes, each organic light emitting diode of the organic light emitting diode array coupled to a corresponding thin film transistor of the transistor array; and a first light absorption layer disposed over the plurality of thin film transistors and between the transistor array and the organic light emitting diode array.

[0030] An organic luminescence device fabrication method includes: forming a thin film transistor on a substrate; forming an insulation layer on the substrate provided with the thin film transistor; forming a first light absorption layer over the thin film transistor; forming a first electrode on the insulation layer; and forming the organic light emission layer over the first light absorption layer and the first electrode; and forming a second electrode on the organic light emission layer.

[0031] Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the present disclosure, and be protected by the following claims. Nothing in this section should be taken as a limitation on those claims. Further aspects and advantages are discussed below in conjunction with the embodiments. It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are included to provide a further understanding of the embodiments and are incorporated herein and constitute a part of this application, illustrate embodiment(s) of the present disclosure and together with the description serve to explain the disclosure. In the drawings: Fig. 1A is a cross-sectional view showing an organic electroluminescence device of the related art; Fig. 1B is an enlarged view largely showing a region A in Fig. 1A; Fig. 2A is a cross-sectional view showing an organic electroluminescence device according to an embodiment of the present disclosure; Fig. 2B is an enlarged view largely showing a region A in Fig. 2A; Fig. 3 is a data sheet illustrating an optical band gap characteristic of a semiconductor layer of organic electroluminescence device according to an embodiment of the present disclosure; Figs. 4A and 4B are planar views showing a formation region of a light absorption layer of an organic electroluminescence device according to an embodiment of the present disclosure, with Fig. 4A not forming part of the claimed invention; Fig. 5 is a data sheet illustrating expected transmittance of a light absorption layer of an organic electroluminescence device according to an embodiment of the present disclosure with respect to wavelength; Fig. 6 is a data sheet comparing characteristics of a thin film transistor when light absorption layers different from one another are applied to the organic electroluminescence device according to an embodiment of the present disclosure; and Figs. 7A through 7F are cross-sectional views illustrating a method of fabricating an organic electroluminescence device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Reference will now be made in detail to an organic electroluminescence device and a fabrication method thereof in accordance with embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. These embodiments introduced hereinafter are provided as examples in order to convey their spirits to the ordinary skilled person in the art. Therefore, these embodiments might be embodied in a different shape, so are not limited to these embodiments described here. In the drawings, the size, thickness and so on of a device can be exaggerated for convenience of explanation. Wherever possible, the same reference numbers will be used throughout this disclosure including the drawings to refer to the same or like parts.

[0034] Fig. 2A is a cross-sectional view showing an organic electroluminescence device according to an embodiment of the present disclosure. In detail, Fig. 2A is a cross-sectional view showing a white OLED device of a bottom emission mode according to an embodiment of the present disclosure. Fig. 2B is an enlarged view largely showing a region A in Fig. 2A.

[0035] Referring to Fig. 2A, the organic electroluminescence device 100 according to an embodiment of the present disclosure is configured with a first substrate 111 and a second substrate (not shown). The first substrate 111 and the second substrate are separated from each other in such a manner as to face each other.

[0036] The organic electroluminescence device 100 includes a thin film transistor array 114 formed on the first substrate 111, and a first electrodes 142 independently formed on the thin film transistor array 114 in every pixel. Also, the organic electroluminescence device 100 includes an organic light emission layer 144 formed on the first electrode 142, and a second electrode 145 formed on the entire surface of the organic light emission layer 144.

[0037] The thin film transistor array 114 includes a driving thin film transistor T which can be formed in any one of an edge stopper structure and a coplanar structure. If the driving thin film transistor T is formed in the edge stopper structure, a bottom gate thin film transistor can be applied to the driving thin film transistor T. Moreover, an etch stopper for etch prevention can be formed on a channel layer opposite to the gate electrode. Meanwhile, the driving thin film transistor T of the coplanar structure allows a gate electrode and source and drain electrodes to be all formed on one surface of an active layer. Also, an inverted coplanar structure corresponding to a bottom gate structure can be applied to the driving thin film transistor T.

[0038] As shown in Fig. 2B, the driving thin film transistor T can be formed in the coplanar structure. Referring to Fig. 2B, the driving thin film transistor T is completed by depositing a buffer layer 112 on the substrate 111 and sequentially forming a semiconductor layer 120, a gate insulation film 121, a gate electrode 122, a first insulation layer 123 and source and drain electrodes 124a and 124b. A second insulation layer 130, a first electrode 142, an organic light emission layer 144 and so on are sequentially formed on the substrate 111 provided with the source and drain electrodes 124a and 124b of the driving thin film transistor T.

[0039] Referring to Figs. 2A and 2B, electrons injected from the second electrode 145 and electric-holes injected from the first electrode 142 are drifted toward the organic light emission layer 144 when a voltage is applied between the first electrode 142 and the second electrode 145. As such, the electrons and the electric-holes applied into the organic light emission layer 144 collide and are recombined with each other within the organic light emission layer 144, thereby generating light. In this case, the first electrode 142 is used as an anode and the second electrode 145 is used as a cathode.

[0040] If the organic electroluminescence device 100 is a white OLED device, the organic light emission layer 144 emits white light. As such, red, green and blue color filters 131, 132 and 133 are formed between the second insulation layer 130 and the first electrode 142 in red, green and blue pixel regions, respectively. Meanwhile, no color filter is formed in a white pixel region. In accordance therewith, the white pixel region allows white light W generated in the organic light emission layer to be output.

[0041] Alternatively, if the organic electroluminescence device is fabricated in the bottom emission mode, light emitted from the organic light emission layer 144 is radiated to the exterior through the first electrode 142 and the first substrate 111. In this case, the second electrode also performs a function of a reflective plate.

[0042] The first electrode 142 can be formed from a transparent conductive material such as ITO (indium-tin-oxide), IZO (indium-zinc-oxide) or others. The second electrode 145 can be formed from an opaque metal material with a reflective property. For example, the second electrode 145 can be formed from one selected from a metal group which includes aluminum Al, gallium Ga, calcium Ca, magnesium Mg and so on.

[0043] The semiconductor layer 120 is formed from an oxide semiconductor material such as IGZO. Preferably, the semiconductor layer 120 is formed from an oxide semiconductor material with mobility of at least 30cm2 / Vs. The oxide semiconductor material is represented in the following chemical formula 1.         [Chemical formula 1]     A w B x C y O z

[0044] In the chemical formula 1, "A", "B" and "C" are one of indium In, gallium Ga, zinc Zn, aluminum Al and tin Sn, respectively. Also, "w", "x", "y" and "z" are natural numbers of not less than 1 but no more than 10.

[0045] However, an oxide semiconductor layer with a high mobility is sensitive to light. To address this matter, the organic electroluminescence device 100 includes a first light absorption layer 136 which is formed over the thin film transistor and used to shield light emitted from the organic light emission layer 144.

[0046] Preferably, the first light absorption layer 136 is formed from a material selectively absorbing wavelength light which can affect deterioration of the semiconductor layer 120. As such, the concentration of heat for the first light absorption layer 136 can be prevented. The wavelength of light affecting the light deterioration of the semiconductor layer 120 can be obtained from an optical band gap characteristic of the semiconductor layer 120.

[0047] Fig. 3 is a data sheet illustrating an optical band gap characteristic of a semiconductor layer of an organic electroluminescence device according to an embodiment of the present disclosure. In detail, Fig. 3 illustrates the optical band gap characteristic of the semiconductor layer which has a mobility of not less than 30cm2 / Vs and is formed from IGZO with a fixed composition ratio.

[0048] Referring to Fig. 3, optical band gap energy of the IGZO semiconductor layer with the mobility of at least 30cm2 / Vs and a fixed composition ratio becomes a range of about 2.75-2.8eV. The optical band gap energy of about 2.75-2.8eV corresponds to energy of light with a wavelength range of 433nm~450nm. As such, when light with wavelengths of no more than 450nm is irradiated, the IGZO semiconductor layer is deteriorated by light.

[0049] In view of this point, the light absorption layer 136 shown in Fig. 3 is designed to absorb larger energies than 2.8eV, i.e. shorter wavelength light than 450nm. As such, the light absorption layer 136 shown in Fig. 3 can be formed from a material with smaller band gap energy than 2.8eV. For example, the light absorption layer 136 can be formed from one non-conductive inorganic material of silicon Si (1.1eV), germanium Ge (0.67eV), copper oxide CuO (1.2eV), gallium arsenide GaAs (1.43eV) and so on, said first light-absorption layer comprising non-conductive inorganic layers not forming part of the claimed invention. The first light absorption layer 136 includes a stacked structure of at least two different color filters selected from a group which consists of red, green, and blue color filters which are formed from organic materials.

[0050] Such a first light absorption layer 136 formed from the organic materials is preferably disposed over the thin film transistor as shown in Figs. 2A and 2B, in order to shield light emitted from the organic light emission layer 144. Additionally, a second light absorption layer 136 is disposed under the thin film transistor, in order to shield external light, said second light absorption layer 136 being formed from a non-conductive inorganic material selected from one of silicon, germanium, copper oxide and gallium arsenide.

[0051] The second light absorption layer 136 which is disposed under the thin film transistor, is formed between the substrate 111 and the buffer layer 112. The second light absorption layer 136 is formed from a non-conductive inorganic material selected from the group of silicon Si (1.1eV), germanium Ge (0.67eV), copper oxide CuO (1.2eV), and gallium arsenide GaAs (1.43 eV).

[0052] When the first light absorption layer 136 is formed in the double layer structure of the red and green color filters 131 and 132, the first light absorption layer 136 is preferably formed in the same layer as red, green and blue color filters which are formed in red, green and blue pixel regions.

[0053] Figs. 4A and 4B are planar views showing a formation region of a light absorption layer of an organic electroluminescence device according to an embodiment of the present disclosure, with Fig. 4A not forming part of the claimed invention.

[0054] Referring to Fig. 4A, the light absorption layer 136 (shown in Fig. 2A) of the organic electroluminescence device of the according to an embodiment of the present disclosure may be locally formed only over the thin film transistors.

[0055] The first light absorption layer 136 (shown in Fig. 2A) of the organic electroluminescence device is formed in the entire area with exception of openings, as shown in Fig. 4B.

[0056] More specifically, the organic electroluminescence device according to an embodiment of the present disclosure includes the red, green and blue pixel regions. The red, green and blue pixel regions are defined by crossing gate lines GL, data lines DL and power lines PL.

[0057] A switching thin film transistor TS, a driving thin film transistor TD connected to the switching thin film transistor TS, the first electrode 142 (shown in Fig. 2A) or other, and a storage capacitor C are formed in each of the red green and blue pixel regions.

[0058] The switching thin film transistor TS includes a gate electrode connected to one of gate lines GL, a source electrode connected to one of the data lines DL, and a drain electrode connected to a gate electrode 122 (shown in Fig. 2B) of the driving thin film transistor TD and the storage capacitor C. The driving thin film transistor TD includes the gate electrode 122 connected to the drain electrode of the switching thin film transistor TS and the storage capacitor C, a source electrode 124a (shown in Fig. 2B) connected to one of the power lines PL, and a drain electrode 124b (shown in Fig. 2B) connected to the first electrode 142 (shown in Fig. 2A).

[0059] The switching thin film transistor TS is turned-on and transfers a data signal on the respective the data line DL to the storage capacitor C and the gate electrode 122 (shown in Fig. 2B) of the driving thin film transistor TD, when a scan pulse is applied to the respective gate line GL. The driving thin film transistor TD replies to the data signal applied to its gate electrode 122 (shown in Fig. 2B) and controls a current I flowing from the respective power line PL toward an organic electroluminescence element (not shown). In accordance therewith, a light quantity emitted from the organic electroluminescence element is adjusted.

[0060] The first light absorption layer 136 (shown in Fig. 2A) is formed not only over the driving thin film transistor TD but also over the switching thin film transistor TS. As described above, the first light absorption layer 136 is formed on the entire area with exception of the openings.

[0061] Fig. 5 is a data sheet illustrating expected transmittance of a light absorption layer of the organic electroluminescence device according to an embodiment of the present disclosure with respect to wavelength. In detail, Fig. 5 is a graphic diagram showing expected transmittance with respect to wavelength when the light absorption layer 136 (shown in Fig. 2A) is formed in the double layer structure of the red and green color filters.

[0062] As seen from Fig. 5, it is evident that the light absorption layer 136 (shown in Fig. 2A) formed in the double layer structure of the red and green color filters 131 and 132 (shown in Fig. 2A) almost completely absorbs light with wavelength of below 600nm. As such, the IGZO semiconductor layer with mobility of 30 cm 2< / Vs can be almost completely protected from deterioration which is caused by light.

[0063] Fig. 6 is a data sheet comparing characteristics of a thin film transistor when light absorption layers different from one another are applied to an organic electroluminescence device according to an embodiment of the present disclosure. In detail, a first graphic diagram illustrates a characteristic of the thin film transistor when a light absorption layer including only a red color filter (not forming part of the claimed invention) is applied. A second graphic diagram illustrates another characteristic of the thin film transistor when a light absorption layer including only a green color filter (not forming part of the claimed invention) is applied. A third graphic diagram illustrates still another characteristic of the thin film transistor when the light absorption layer 136 (shown in Fig. 2A) formed in the double layer structure of the red and green color filters 131 and 132 (shown in Fig. 2A) according to an according to an embodiment of the present disclosure is applied.

[0064] As seen from Fig. 6, it is evident that the light absorption layer 136 (shown in Fig. 2A) formed in the double layer structure of the red and green color filters 131 and 132 (shown in Fig. 2A) according to an embodiment of the present disclosure largely enhances a characteristic of the thin film transistor, compared to other light absorption layers including only one of the red and green color filters. In detail, when the first light absorption layer 136 (shown in Fig. 2A) formed in the double layer structure of the red and green color filters 131 and 132 (shown in Fig. 2A) according to an embodiment of the present disclosure is applied, the threshold voltage Vth of the thin film transistor decreases by 0.2V (i.e., ΔVth = -0.2V). Meanwhile, the threshold voltage Vth of the thin film transistor decreases by 13V (i.e., ΔVth = -13V) when the light absorption layer including only the red color filter is applied. Also, the threshold voltage Vth of the thin film transistor decreases by 12V (i.e., ΔVth = -12V) when the light absorption layer including only the green color filter is applied. In other words, it is evident that the thin film transistor deteriorates when the light absorption layer including only one of the red and green color filters is applied.

[0065] Figs. 7A through 7F are cross-sectional views illustrating a method of fabricating an organic electroluminescence device according to an embodiment of the present disclosure.

[0066] Referring to Fig. 7A, the method of fabricating an organic electroluminescence device according to an embodiment of the present disclosure allows a thin film transistor array 114 including driving thin film transistors T to be firstly formed on a substrate 111.

[0067] In order to form the driving thin film transistors T, a buffer layer 112 is firstly formed on the entire surface of the substrate 111 and active layers 120' are formed on the buffer layer 112. The active layers 120' are formed from an oxide with a high mobility. Also, the active layers 120' can be formed using one of a vapor deposition method and a photolithography method. For example, the active layers 120' are prepared by forming an oxide film of IGZO or others using the vapor deposition method and patterning the oxide film. The formation of a film is performed in order to form a polycrystalline oxide semiconductor sintered compound which is formed from IGZO or others. One of a sputtering method and a pulse laser deposition (PLD) method can be used in the formation of the film. Preferably, the sputtering method is used for mass production.

[0068] The process of patterning the oxide film can be performed by forming photoresist patterns on the oxide film of IGZO or others corresponding to portions, which the active layers 120' will be formed, and then etching the oxide film using an acid solution such as an mixed liquid of hydrochloric acid, nitric acid and dilute sulfuric acid, another mixed liquid of phosphoric acid, nitric acid and acetic acid, or others. The aqueous solution including phosphoric acid, nitric acid and acetic acid can remove exposed portion of an IGZO film during a short time.

[0069] A gate insulation film 121 and a gate electrode 122 are sequentially formed in the central region of each active layer 120'. Subsequently, a first insulation layer 123 and source and drain electrodes 124a and 124b are sequentially formed, thereby completing the driving thin film transistor T.

[0070] As shown in Fig. 7B, a second insulation layer 130 is formed on the entire surface of the substrate 111 provided with the source and drain electrodes 124a and 124b of the driving thin film transistors T. The second insulation layer 130 can be prepared by coating an insulation material on the entire surface of the substrate 111. As an example of the insulation material, one of an organic insulation material and an inorganic insulation material can be used. The organic insulation material can become an acryl based organic compound or others. The inorganic insulation material can become silicon oxide SiOx, silicon nitride SiNx or others.

[0071] Also, red, green and blue color filters 131, 132 and 133 are formed on the second insulation layer 130 corresponding to respective pixel regions, respectively. At the same time, a first light absorption layer 136 is also formed in a stacked structure of the red and green color filters 131 and 132.

[0072] The first light absorption layer 136 is formed over not only the driving thin film transistors T but also switching thin film transistors even though it not shown in the drawings. The formation range of the first light absorption layer 136 is the entire area with exception of openings.

[0073] The procedure of forming the red, green and blue color filters 131, 132 and 133 and the first light absorption layer 136 will now be described in detail. First, the red color filter 131 is formed on the second insulation layer 130 corresponding to the red pixel region and the thin film transistors by coating a red color resist including a red dye on the second insulation layer 130 and patterning the red color resist through a photolithography procedure and an etching process. The green color filter 132 is formed on the second insulation layer 130 corresponding the green pixel region and on the red color filter 131 which is disposed over the thin film transistors, by coating a green color resist including a green dye on the second insulation layer 130 provided with the red color filter 131 and patterning the green color resist through another photolithography procedure and another etching process. The blue color filter 133 is formed on the second insulation layer 130 corresponding to the blue pixel region, by coating a blue color resist including a blue dye on the insulation layer 130 provided with the red and green color filters 131 and 132 and patterning the blue color resist through still another photolithography procedure and still another etching process.

[0074] In this way, the red, green and blue color filters 131, 132 and 133 are formed in the red, green and blue pixel regions, respectively, and the first light absorption layer 136 including the stacked red and green color filters 131 and 132 are formed over the thin film transistors. Although it is explained that the first light absorption layer 136 is formed in a double layer structure of the red and green color filters 131 and 132, the first light absorption layer 136 can be formed in a triple layer structure of the red, green and blue color filters 131, 132 and 133. In the stacking order of the color filters, it is explained herein that the red color filter 131 is first formed, but the green color filter 132 can be first formed. However, the stacking order of the color filters is preferably set in consideration of the degree of deterioration caused by a developer.

[0075] Referring to Fig. 7C, drain contact holes 141 are formed in the second insulation layer provided with the red, green and blue color filters 131, 132 and 133 and the first light absorption layer 136. Also, first electrodes 142 are formed on the second insulation layer 130 provided with the drain contact holes 141. Each of the first electrodes 142 is connected to the respective drain electrode 124b through the respective drain contact hole 141. The first electrodes 142 are formed by depositing a transparent conductive material on the entire surface of the second insulation layer 130 provided with the drain contact holes 141 and patterning the deposited transparent conductive material through a photolithography procedure and an etching process.

[0076] As shown in Fig. 7D, a passivation layer 143 is formed by depositing an insulation material on the entire surface of the substrate 111. The passivation layer 143 is partially removed through a photolithography procedure and an etching process and partially exposes each of the first electrodes 142. Such a passivation layer 143 is used to protect the thin film transistors from moisture and alien substances.

[0077] Referring to Fig. 7E, an organic light emission layer 144 and a second electrode 145 are sequentially formed on the partially exposed first electrodes 142.

[0078] Referring to Fig. 7F, the first substrate, 111 which is provided with the second electrode 145 and faces a second substrate 211, is combined with the second substrate 211 by means of a sealant 301. In accordance therewith, the organic electroluminescence device according to an embodiment of the present disclosure is completed.

[0079] As described above, the present disclosure has the light absorption layers disposed over and under the thin film transistor. In accordance therewith, the deterioration of the thin film transistor caused by light can be prevented. As a result, the organic electroluminescence device can enhance reliability against light.

[0080] Although the present disclosure has been limitedly explained regarding only the embodiments described above, it should be understood by the ordinary skilled person in the art that the present disclosure is not limited to these embodiments, but rather that various changes or modifications thereof are possible without departing from the scope of the present invention, which is determined only by the appended claims.

Claims

1. An organic electroluminescence device including red, green and blue pixel regions comprising: - a substrate (111); - a thin film transistor (T) on the substrate (111) in each of the pixel regions; - an insulation layer (130) on the thin film transistor (T) coating the entire surface of the substrate (111);- a first electrode (142) in each of the pixel regions connected to the corresponding thin film transistor (T); - an organic light emission layer (144) on the first electrodes (142); - a second electrode (145) on the organic light emission layer (144); - red, green and blue color filters (131, 132, 133) between the insultation layer (130) and the first electrode (142) in corresponding pixel regions; - a first light absorption layer (136) that includes a stacked structure of at least two different color filters (131, 132) selected from a group which consists of the red, green and blue color filters (131, 132, 133), the first color filter of the at least two different color filters disposed on the insulation layer (130) in corresponding pixel regions and at the same time disposed on the thin film transistor (T) and the at least second color filter of the at least two different color filters disposed on the insulation layer (130) in corresponding pixel regions and at the same time disposed on the first color filter of the at least two different color filters over the thin film transistor (T), the first light absorption layer (136) disposed between the thin film transistor (T) and the organic light emission layer (144), the first light absorption layer (136) configured to shield the thin film transistor (T) from light emitted from the organic light emission layer (144), the first light absorption layer (136) covers an entire area of the organic electroluminescence device including at least one gate line (GL), at least one data line (DL) and at least one power line (PL) except at openings corresponding to the pixel regions; - a second light absorption layer formed from a non-conductive inorganic material selected from one of silicon, Germanium, copper oxide and gallium arsenide, wherein the second light absorption layer is disposed under the thin film transistor (T), disposed between the substrate (111) and a buffer layer (112) underneath a semiconductor layer, and is configured to shield the thin film transistor (T) from external light; and - a passivation layer (143) on the thin film transistor (T) between the first light absorption layer (136) and the organic light emission layer (144), the passivation layer (143) partly exposing the first electrode (142), - wherein a gate insulation film (121) and a gate electrode (122) of the thin film transistor (T) are sequentially formed on the semiconductor layer of the thin film transistor (T), so that the first light absorption layer (136), the gate insulation film (121) and the gate electrode (122) are positioned between the organic light emission layer (144) and the semiconductor layer, - wherein the semiconductor layer is formed from an oxide represented by the following chemical formula 1:         [Chemical formula 1]     AwBxCyOz wherein "A", "B" and "C" are one of indium In, gallium Ga, and zinc Zn, respectively, and "w", "x", "y" and "z" are natural numbers of not less than 1 but no more than 10.

2. The organic electroluminescence device of claim 1, wherein the thin film transistor (T) is one of a coplanar structure.

3. A method of fabricating an organic electroluminescence device according to claim 1 including red, green and blue pixel regions, the method comprising: - forming a thin film transistor (T) on a substrate (111) in each of the pixel regions; - sequentially forming a second light absorption layer and a buffer layer (120) between the substrate (111) and the thin film transistor (T);- forming an insulation layer (130) on the thin film transistor (T) coating the entire surface of the substrate (111); - forming a first electrode (142) in each of the pixel regions on the insulation layer (130) connected to the corresponding thin film transistor (T); - forming red, green and blue color filters (131, 132, 133) between the insultation layer (130) and the first electrode (142) in corresponding pixel regions and at the same time forming a first light absorption layer (136) over the thin film transistor (T), wherein the first light absorption layer (136) includes a stacked structure of at least two different color filters (131, 132) selected from a group which consists of red, green and blue color filters (131, 132, 133), the first color filter is formed on the insulation layer (130) in corresponding pixel regions and at the same time disposed on the thin film transistor (T) and the at least second color filter disposed on the insulation layer (130) in corresponding pixel regions and at the same time disposed on the first color filter over the thin film transistor (T), wherein the first absorption layer (136) covers an entire area of the organic electroluminescence device including at least one gate line (GL), at least one data line (DL) and at least one power line (PL) except at openings corresponding to pixel regions; - forming a passivation layer (143) by depositing an insulation material on the entire surface of the substrate (111); - partially removing the passivation layer (143) so as to partly expose the first electrode (142); - forming the organic light emission layer on the passivation layer (143) over the first light absorption layer (136) and on the first electrode (142); and - forming a second electrode (145) on the organic light emission layer (144), and - wherein a gate insulation film (121) and a gate electrode (122) of the thin film transistor (T) are sequentially formed on a semiconductor layer of the thin film transistor (T), so that the first light absorption layer (136), the gate insulation film (121) and the gate electrode (122) are positioned between the organic light emission layer (144) and the semiconductor layer, - wherein the semiconductor layer is formed from an oxide represented by the following chemical formula 1:         [Chemical formula 1]     AwBxCyOz, wherein "A", "B" and "C" are one of indium In, gallium Ga, and zinc Zn, respectively, and "w", "x", "y" and "z" are natural numbers of not less than 1 but no more than 10, - wherein the second light absorption layer is disposed under the thin film transistor (T), and disposed between the substrate (111) and a buffer layer (112) underneath the semiconductor layer.

4. The method of claim 3, wherein the formation of the first light absorption layer (136) is performed between the formation of the insulation layer (130) and the formation of the first electrode (142).