KR101476444B1 - Organic electroluminescent display device - Google Patents

Abstract

The present invention provides a transistor comprising: a transistor located on a substrate; A reflective layer located on the transistor; An anode located on the reflective layer and connected to a source or drain of the transistor; A bank layer located on the anode and having an opening; A lower common layer located on the anode; A light emitting layer located on the lower common layer; An electron transport layer positioned on the light emitting layer; And a cathode composed of lithium (Li) positioned on the electron transporting layer and silver (Ag) located on the lithium, wherein the thickness of lithium is 5 ANGSTROM to 10 ANGSTROM and the thickness of silver is 50 ANGSTROM to 150 ANGSTROM. A light emitting display device is provided.

Organic electroluminescence display, cathode, transmittance

Description

[0001] The present invention relates to an organic light emitting display,

The present invention relates to an organic light emitting display.

An organic electroluminescent device used in an organic electroluminescent display device is a self-luminous device in which a light emitting layer is formed between two electrodes located on a substrate.

In addition, the organic light emitting display device may include a top emission type, a bottom emission type, or a dual emission type depending on a direction in which light is emitted. It is divided into a passive matrix and an active matrix depending on the driving method.

The subpixels disposed in the organic light emitting display include a switching transistor, a driving transistor, a capacitor, an anode, an organic light emitting layer, and a cathode.

Meanwhile, in the conventional top emission type organic light emitting display, in order to increase the transmittance of the transparent cathode, the sheet resistance is increased when the thickness of the metal constituting the cathode is lowered, and the transmittance is lowered when the thickness of the metal is increased in order to lower the sheet resistance.

In addition, when a device is manufactured in consideration of the sheet resistance and the transmittance, since the work function of the cathode into which electrons are injected is high, an energy band gap with the Lowest Unoccupied Molecular Orbital (LUMO) of the electron transport layer increases the threshold voltage there was.

Therefore, the conventional front emission type organic light emitting display device should be improved to solve the above problems.

An object of the present invention is to provide an organic electroluminescent display device capable of realizing high efficiency, low voltage characteristics, low sheet resistance characteristics of electrodes and high transmittance of a device.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a transistor located on a substrate; A reflective layer located on the transistor; An anode located on the reflective layer and connected to a source or drain of the transistor; A bank layer located on the anode and having an opening; A lower common layer located on the anode; A light emitting layer located on the lower common layer; An electron transport layer positioned on the light emitting layer; And a cathode composed of lithium (Li) positioned on the electron transporting layer and silver (Ag) located on the lithium, wherein the thickness of lithium is 5 ANGSTROM to 10 ANGSTROM and the thickness of silver is 50 ANGSTROM to 150 ANGSTROM. A light emitting display device is provided.

delete

delete

The sheet resistance of the cathode may be 3? To 15 ?.

The lower common layer may include a hole injection layer and a hole transport layer.

The auxiliary electrode may be located on the cathode.

The cathode may further include a protective film disposed thereon.

The reflective layer may comprise aluminum (Al), silver (Ag), or aluminum-neodymium (AlNd).

The anode may include indium tin oxide (ITO) or indium zinc oxide (IZO).

The present invention provides an organic electroluminescent display device capable of realizing high efficiency, low voltage characteristics, low sheet resistance characteristics of electrodes and high transmittance of the device. Further, the present invention can have low work function properties of the cathode. Further, there is an effect that it is possible to provide a structure in which the electron injection layer can be omitted and the problem of the threshold voltage of the device being increased.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of an organic light emitting display according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating an implementation of an organic light emitting display using the configuration of FIG.

Referring to FIG. 1, an organic light emitting display according to an exemplary embodiment of the present invention may include a reflective layer 121 on a substrate 110. And may include an anode 122 located on the reflective layer 121. [ It may also include a bank layer 123 located on the anode 122 and having an opening. It may also include a lower common layer 124 located on the anode 122. [ The light emitting layer 125 may be disposed on the lower common layer 124. Further, it may include an electron transport layer 126 located on the light emitting layer 125. And may include cathodes 127 and 128 composed of lithium (Li) 127 positioned on the electron transporting layer 126 and silver (Ag) 128 located on the lithium 127. It may also include a sealing substrate 140 that is coalesced with the substrate 110.

The organic light emitting display having such a configuration may be implemented as a full-emission type active matrix as shown in FIG.

Referring to FIG. 2, a substrate 110 may be positioned.

The substrate 110 can be selected to have excellent mechanical strength and dimensional stability as a material for forming devices. As a material of the substrate 110, a glass plate, a metal plate, a ceramic plate, or a plastic plate (polycarbonate resin, acrylic resin, vinyl chloride resin, polyethylene terephthalate resin, polyimide resin, polyester resin, Resin, etc.) and the like.

Transistors may be located on the substrate 110.

The transistor may comprise a gate 102.

The gate 102 may be formed of any one selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper Or an alloy thereof.

The gate 102 may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, Ne, Or an alloy of any one selected from the above. Also, the gate 102 may be a double layer of molybdenum / aluminum-neodymium or molybdenum / aluminum.

The transistor may include a first insulating film 103 located on the gate 102. The first insulating film 103 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof, but is not limited thereto.

The transistor may include an active layer 104 located on the first insulating film 103. The active layer 104 may comprise amorphous silicon or polycrystalline silicon crystallized therefrom.

Although not shown here, the active layer 104 may include a channel region, a source region, and a drain region, and the source region and the drain region may be doped with P-type or N-type impurities. In addition, the active layer 104 may include an ohmic contact layer 105 for lowering the contact resistance.

The transistor may comprise a source 106a and a drain 106b located on the active layer 104. The source 106a and the drain 106b may be formed of a single layer or multiple layers and may be formed of a single layer of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu).

When the source 106a and the drain 106b are multilayered, they may be formed of a triple layer of molybdenum / aluminum-neodymium, molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum.

The transistor may include a second insulating film 107 located on the source 106a and the drain 106b. The second insulating film 107 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof, but is not limited thereto.

The second insulating film 107 may be a passivation film. On the other hand, a planarizing film 108 for increasing the flatness may be formed on the second insulating film 107.

Although the above description has been made with respect to the Bamam gate type transistor as an example of the transistor located on the substrate 110, the transistor may also be formed in a top gate type.

A reflective layer 121 may be disposed on the third insulating film 108. The reflective layer 121 may include aluminum (Al), silver (Ag), or aluminum-neodymium (AlNd).

An anode 122 connected to the source 106a or the drain 106b of the transistor may be disposed on the reflective layer 121. [ The anode 122 may be made of transparent indium tin oxide (ITO) or indium zinc oxide (IZO), but the present invention is not limited thereto.

On the anode 122, a bank layer 123 having an opening may be located. The bank layer 123 may include an organic material such as a benzocyclobutene (BCB) based resin, an acrylic based resin, or a polyimide resin.

The lower common layer 124 may be located in the opening of the bank layer 123. The lower common layer 124 may include a hole injection layer and a hole transport layer.

The hole injecting layer may serve to smooth the injection of holes and may be formed of CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene), PANI (polyaniline) and NPD (N, N'-diphenyl benzidine), but the present invention is not limited thereto.

The hole transport layer plays a role of facilitating the transport of holes, and the hole transport layer functions as a hole transporting layer for transporting holes, such as NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine), TPD (N, N'- -bis- (phenyl) -benzidine), s-TAD and 4,4 ', 4 "-tris (N-3-methylphenyl-N- phenylamino) -triphenylamine But is not limited thereto.

The light emitting layer 125 may be located on the lower common layer 124. The light emitting layer 125 may include materials that emit red, green, blue, and white light, and may be formed using phosphorescent or fluorescent materials.

When the light-emitting layer 125 is red, it includes a host material including CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl) wherein the dopant comprises at least one selected from the group consisting of iridium, iridium, PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium) and PtOEP (octaethylporphyrin platinum) Or PBD: Eu (DBM) 3 (Phen) or Perylene. However, the present invention is not limited thereto.

When the light emitting layer 125 is green, it may comprise phosphorescent material including a dopant material including a host material including CBP or mCP and containing Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium) Alternatively, it may be made of a fluorescent material including Alq3 (tris (8-hydroxyquinolino) aluminum), but is not limited thereto.

When the light emitting layer 125 is blue, it may include a host material including CBP or mCP, and may include a phosphorescent material including a dopant material including (4,6-F2ppy) 2Irpic. Alternatively, the fluorescent material may include any one selected from the group consisting of spiro-DPVBi, spiro-6P, distyrylbenzene (DSB), distyrylarylene (DSA), PFO polymer, and PPV polymer. It is not limited.

The electron transport layer 126 may be located on the light emitting layer 125.

The electron transport layer 126 plays a role of facilitating transport of electrons and may be made of any one or more selected from the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq and SAlq But are not limited thereto.

On the electron transporting layer 126, cathodes 127 and 128 composed of lithium (Li) 127 and silver (Ag) 128 positioned on the lithium 127 can be positioned.

Here, the thickness of the lithium 127 may be in the range of 5 ANGSTROM to 10 ANGSTROM. If the thickness of the lithium 127 is less than 5 angstroms, the sheet resistance can be lowered. If the thickness of the lithium 127 is less than 10 angstroms, the problem of lowering the transmittance within a range where the sheet resistance does not increase much can be prevented.

Here, the thickness of the silver 128 may be in the range of 50 ANGSTROM to 150 ANGSTROM. If the thickness of the silver 128 is less than 50 Å, the sheet resistance can be reduced. If the thickness of the silver 128 is less than 150 Å, the decrease in the transmittance can be prevented.

As described above, when the thickness of the lithium 127 is formed in the range of 5 to 10 angstroms and the thickness of the silver 128 is formed in the range of 50 to 150 angstroms, the transparency of the electrode can be increased to improve the transmittance.

When the thickness of the lithium 127 is in the range of 5 Å to 10 Å and the thickness of the silver 128 is in the range of 50 Å to 150 Å, the sheet resistances of the cathodes 127 and 128 may be approximately 3 Ω to 15 Ω.

Hereinafter, with reference to Table 1 and FIG. 3, reference is made to a comparison table of cathodes 127 and 128 according to an embodiment of the present invention and a cathode according to the related art, and a change in driving voltage, power efficiency, .

3 is a graph showing the intensity versus wavelength of Comparative Examples A to C and Example D of Table 1. FIG.

Table 1 below shows comparison charts under the measurement conditions of 25 ° C, 1 atm, and 1000 nit.

Cathode structure (unit of thickness: A)
Voltage
(V) efficiency CIE cd / A Im / W x y Comparative Example A LiF (10) / Al (5) / Ag (100) 6.5 19 9.2 0.315 0.663 Comparative Example B LiF (10) / Ag (100) 15.5 2.2 0.4 0.232 0.722 Comparative Example C Li (10) / Al (5) / Ag (100) 4.4 22 16 0.290 0.684 Example D Li (10) / Ag (100) 3.4 25 23 0.294 0.681

In Table 1, Comparative Examples A to C are numerical values for the driving voltage, power efficiency and color coordinates according to the thickness of the cathode applied to the prior art, and Example D shows the thickness of the cathode applied to the embodiment of the present invention Power efficiency, and color coordinates according to the following equation.

Referring to FIG. 3, Example D (D) according to an embodiment of the present invention shows a large difference in wavelength-to-intensity ratio from Comparative Examples A to C (A), Comparative Example C .

However, referring to Table 1, Example D according to an embodiment of the present invention shows superior performance in terms of driving voltage and power efficiency as compared with Comparative Examples A to C of the prior art. Here, it can be seen that the driving voltage of the embodiment D according to the embodiment of the present invention is about 3V lower than that of the comparative example A, and the power efficiency is increased from 9.2 Im / W to 23 Im / W.

That is, when the cathodes 127 and 128 are formed under the same conditions as those of the embodiment of the present invention, the driving voltage can be lowered and the power efficiency can be increased even if the electron injection layer is omitted.

Meanwhile, the organic light emitting display device according to an embodiment of the present invention may further include the configuration shown in FIG. 4 or FIG.

4 and 5 are schematic configuration diagrams of an organic light emitting display according to a modified embodiment of FIG.

Referring to FIGS. 4 and 5, the organic light emitting display according to the modified embodiment of the present invention may include a reflective layer 121 on a substrate 110, as described above with reference to FIG. And may include an anode 122 located on the reflective layer 121. [ It may also include a bank layer 123 located on the anode 122 and having an opening. It may also include a lower common layer 124 located on the anode 122. [ The light emitting layer 125 may be disposed on the lower common layer 124. Further, it may include an electron transport layer 126 located on the light emitting layer 125. And may include cathodes 127 and 128 composed of lithium (Li) 127 positioned on the electron transporting layer 126 and silver (Ag) 128 located on the lithium 127. It may also include a sealing substrate 140 that is coalesced with the substrate 110.

Here, referring to FIG. 4, one of the auxiliary electrodes or the protective layer 130 may be formed on the cathodes 127 and 128. 4, the materials of the cathodes 127 and 128 are formed of lithium 127 and silver 128, and the thickness of the lithium 127 is set to < RTI ID = 0.0 > And the thickness of the silver 128 may be in the range of 50 ANGSTROM to 150 ANGSTROM.

Referring to FIG. 5, both the auxiliary electrode 130 and the protective layer 135 may be formed on the cathodes 127 and 128. 5, the materials of the cathodes 127 and 128 are formed of lithium 127 and silver 128, and the thickness of the lithium 127 is set to < RTI ID = 0.0 > And the thickness of the silver 128 may be in the range of 50 ANGSTROM to 150 ANGSTROM.

As described above, one embodiment of the present invention provides an organic electroluminescent display device capable of realizing a high efficiency, a low voltage characteristic, a low sheet resistance characteristic of an electrode, and a high transmittance of a device. Further, the present invention can have low work function properties of the cathode. Further, there is an effect that it is possible to provide a structure in which the electron injection layer can be omitted and the problem of the threshold voltage of the device being increased.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

1 is a schematic view of an organic light emitting display device according to an embodiment of the present invention;

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display.

Fig. 3 is a graph showing the intensity versus wavelength of Comparative Examples A to C and Example D in Table 1. Fig.

FIG. 4 and FIG. 5 are schematic diagrams of an organic light emitting display device according to a modified embodiment of FIG. 1;

DESCRIPTION OF THE REFERENCE NUMERALS

110: substrate 102: gate

103: first insulating film 107: second insulating film

121: reflective layer 122: anode

124: lower common layer 125: light emitting layer

126: electron transport layer 127: lithium

128: silver 140: sealing substrate

Claims (9)

A transistor located on a substrate; A reflective layer located on the transistor; An anode located on the reflective layer and connected to a source or a drain of the transistor; A bank layer located on the anode and having an opening; A lower common layer located on the anode; A light emitting layer located on the lower common layer; An electron transport layer disposed on the light emitting layer; And And a cathode composed of lithium (Li) positioned on the electron transporting layer and silver (Ag) located on the lithium, Wherein the thickness of the lithium is between 5 Å and 10 Å, and the thickness of the silver is between 50 Å and 150 Å. delete delete The method according to claim 1, The sheet resistance of the cathode, Wherein the organic electroluminescent display device has a resistance of 3? To 15?. The method according to claim 1, Wherein the lower common layer comprises: An organic light emitting display device comprising a hole injection layer and a hole transport layer. The method according to claim 1, On the cathode, And an auxiliary electrode is disposed on the organic light emitting display device. The method according to claim 1, On the cathode, And a protective film is disposed on the organic light emitting display device. The method according to claim 1, Wherein, An organic electroluminescent display device comprising aluminum (Al), silver (Ag), or aluminum-neodymium (AlNd). The method according to claim 1, The anode, An organic electroluminescent display device including ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).

Images