Organic Light Emitting Device

Abstract

The present Invention relates to an organic light emitting device comprising: (i) an anode; (ii) a cathode; (iii) at least one light emitting layer arranged between the anode and the cathode; (iv) optionally a first hole injection layer comprising a first hole injection compound, the first hole injection layer being arranged between the anode and the light emitting layer and the hole injection layer being adjacent to the anode; (v) a first hole transport layer comprising a first hole transport matrix compound wherein the first hole transport layer is arranged a) between the first hole injection layer and the light emitting layer and adjacent to the first hole injection layer; or b) between the anode and the light emitting layer and adjacent to the anode; (vi) a second hole injection layer arranged between the first hole transport layer and the light emitting layer, wherein the second hole injection layer is adjacent to the first hole transport layer and wherein the second hole injection layer comprises a second hole injection compound; wherein the second hole injection compound is a halo-genated fullerene, a partially or fully halogenated metal complex or a mixture thereof.

Claims

1. Organic light emitting device comprising: (i) an anode; (ii) a cathode; (iii) at least one light emitting layer arranged between the anode and the cathode; (iv) optionally a first hole injection layer comprising a first hole injection compound, the first hole injection layer being arranged between the anode and the light emitting layer and the hole injection layer being adjacent to the anode; (v) a first hole transport layer comprising a first hole transport matrix compound, wherein the first hole transport layer is arranged a) between the first hole injection layer and the light emitting layer and adjacent to the first hole injection layer; or b) between the anode and the light emitting layer and adjacent to the anode; (vi) a second hole injection layer arranged between the first hole transport layer and the light emitting layer, wherein the second hole injection layer is adjacent to the first hole transport layer and wherein the second hole injection layer comprises a second hole injection compound; wherein the second hole injection compound is a halogenated fullerene, a partially or fully halogenated metal complex or a mixture thereof.

2. The organic light emitting device according to claim 1 wherein the first hole injection layer further comprises a second hole transport matrix compound.

3. The organic light emitting device according to claim 1, wherein the second hole injection layer further comprises a third hole transport matrix compound.

4. The organic light emitting device according to claim 1, wherein the organic light emitting device further comprises a second hole transport layer arranged between the second hole injection layer and the light emitting layer, wherein the second hole transport layer is adjacent to the second hole injection layer and wherein the second hole transport layer comprises a fourth hole transport matrix compound.

5. The organic light emitting device according to claim 1, wherein the halogenated fullerene is a fluorinated fullerene and/or the partially or fully halogenated metal complex is a partially or fully fluorinated metal complex.

6. The organic light emitting device according to claim 1, wherein the halogenated fullerene has the formula C.sub.xF.sub.y wherein x is an even integer from 60 to 120 and y is from x/2 to 4x/5.

7. The organic light emitting device according to claim 6, wherein x is 60.

8. The organic light emitting device according to claim 6, wherein the halogenated fullerene has the formula C.sub.60F.sub.48.

9. The organic light emitting diode according to claim 1, wherein the halogenated metal complex has the following formula (I) ##STR00014## wherein M.sup.x⊕ is a x-valent cation of a metal selected from alkali metals, alkaline earth metals, rare earth metals and Al, Ga, In, Sn, Pb, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn and Cd; x is 1 for M selected from alkali metals; 2 for M selected from alkaline earth metals, Pb, Mn, Fe, Co, Ni, Zn and Cd; 2 or 3 for M selected from rare earth metals; 3 for Al, Ga, In; 2, 3 or 4 for Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; and 2 or 4 for Sn; B.sup.1 and B.sup.2 is independently selected from partially or fully halogenated C.sub.3 to C.sub.20 alkyl, C.sub.3 to C.sub.20 cycloalkyl or C.sub.3 to C.sub.20 arylalkyl.

10. The organic light emitting device according to claim 1, wherein the light emitting layer comprises a phosphorescent emitter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0171] These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, of which:

[0172] FIG. 1 is a schematic sectional view of an organic light-emitting diode (MED), according to an exemplary embodiment of the present invention;

[0173] FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0174] FIG. 3 is a schematic sectional view of a tandem OLED comprising a charge generation layer, according to an exemplary embodiment of the present invention.

EMBODIMENTS OF THE INVENTIVE DEVICE

[0175] Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The exemplary embodiments are described below, in order to explain the aspects of the present invention, by referring to the figures.

[0176] Herein, when a first element is referred to as being formed or disposed “on” a second element, the first element can be disposed directly on the second element, or one or more other elements may be disposed there between. When a first element is referred to as being formed or disposed “directly on” a second element, no other elements are disposed there between.

[0177] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED) 100, according to an exemplary embodiment of the present invention. The OLED 100 includes an anode 110, a first hole injection layer (HIL) 120, a first hole transport layer (HTL) 130, a second hole injection layer 140, an emission layer (EML) 150, an electron transport layer (ETL) 160. The electron transport layer (ETL) 160 is formed directly on the EML 150. Onto the electron transport layer (En) 160, an electron injection layer (EIL) 180 is disposed. The cathode 190 is disposed directly onto the electron injection layer (EIL) 180.

[0178] Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

[0179] FIG. 2 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 2 differs from FIG. 1 in that the OLED 100 of FIG. 2 comprises a second hole transport layer 145 and a hole blocking layer (HBL) 155.

[0180] Referring to FIG. 2, the OLED 100 includes an anode no, a first hole injection layer (HIL) 120, a first hole transport layer (HTL) 130, a second hole injection layer 140, second hole transport layer 145, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (En) 160, an electron injection layer (EIL) 180 and a cathode electrode 190.

[0181] FIG. 3 is a schematic sectional view of a tandem OLED 200, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 further comprises a charge generation layer and a second emission layer.

[0182] Referring to FIG. 3, the OLED 200 includes an anode no, a first hole injection layer (HIL) 120, a first hole transport layer (HTL) 130, a second hole injection layer 140, a second hole transport layer 145, a first emission layer (EML) 150, a first hole blocking layer (HBL) 155, a first electron transport layer (ETL) 160, an n-type charge generation layer (n-type CGL) 185, a hole generating layer (p-type charge generation layer; p-type GCL) 135, a third hole transport layer (HTL) 141, a fourth hole transport layer 146, a second emission layer (EML) 151, a second hole blocking layer (EBL) 156, a second electron transport layer (ETL) 161, a second electron injection layer (EIL) 181 and a cathode 190.

[0183] While not shown in FIG. 1, FIG. 2 and FIG. 3, a sealing layer may further be formed on the cathode electrodes 190, in order to seal the OLEDs 100 and 200. Likewise, while also not shown in FIG. 1, FIG. 2 and FIG. 3, the layers, beginning with the anode, may be formed on a substrate adjacent to the anode. In addition, various other modifications may be applied thereto.

[0184] Hereinafter, one or more exemplary embodiments of the present invention will be described in detail with, reference to the following examples. However, these examples are not intended to limit the purpose and scope of the one or more exemplary embodiments of the present invention.

Experimental Part

[0185] Supporting materials for device experiments

[0186] F1 is

##STR00008##

[0187] N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, CAS 1242056-42-3;

[0188] F2 is

##STR00009##

[0189] 9-([1,1′-biphenyl]-3-yl)-9′-([1,1′-biphenyl]-4-yl)-9H,9′H-3,3′-bicarbazole, CAS 1643479-47-3;

[0190] F3 is

##STR00010##

8-(4-(4,6-di(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinoline, CAS 1312928-44-1;

[0191] F4 is

##STR00011##

(2-(4-phenylpyridin-2-yl)phenyl)bis(2-(pyridin-2-yl)phenyl)iridium, CAS 1215281-24-5;

[0192] F5 is

##STR00012##

2,4-diphenyl-6-(3′-(triphenylen-2-yl)-[1,1′-biphenyl]-3-yl)-1,3,5-triazine, CAS 1638271-85-8;

[0193] F6 is

##STR00013##

[0194] 3-phenyl-3H-benzo[b]dinaphtho[2,1-d:1′,2′-f]phosphepine-3-oxide, CAS 597578-38-6;

[0195] GHM020S is an emitter host and EL-GD0108S is a green phosphorescent emitter dopant, both commercially available from SDI, Korea.

[0196] ITO is indium tin oxide.

[0197] Standard procedures

[0198] Voltage stability

[0199] OLEDs are driven by constant current circuits. Those circuits can supply a cons current over a given voltage range. The wider the voltage range, the wider the power losses of such devices. Hence, the change of driving voltage upon driving needs to be minimized.

[0200] The driving voltage of an OLED is temperature dependent. Therefore, voltage stability needs to be judged in thermal equilibrium. Thermal equilibrium is reached after one hour of driving.

[0201] Voltage stability is measured by taking the difference of the driving voltage after 50 hours and after 1 hour driving at a constant current density. Here, a current density of 30 mA/cm.sup.2 is used. Measurements are done at room temperature.

[0202] dU[V]=U(50 h, 30 mA/cm.sup.2)−U(1 h, 30 mA/cm.sup.2)

EXAMPLES

[0203] 1) Green phosphorescent OLED comprising the second hole injection layer p-doped with a fluorinated metal complex or with fluorinated fullerene compound

[0204] Table 1a schematically describes the model device.

TABLE-US-00001 TABLE 1a c d Material [vol %] [nm] ITO 100 90 F1:PD-2 92:8  10 F1 100 130 F2:p-dopant (100 − x) x 10 F2 100 20 GHM020S:EL-GD0108S 90:10 40 F3:LiQ 50:50 36 Al 100 100

[0205] The results are given in Table 1b

TABLE-US-00002 TABLE 1b EQE c U (10 mA/cm.sup.2) p-dopant [vol %] (10 mA/cm.sup.2) [%] CIE-y PD1 1 4.5 19.7 0.619 PD2 1 4.3 19.3 0.628 PD2 5 4.2 18.2 0.626 PD2 10 4.2 18.1 0.625 C.sub.60F.sub.48 1 4.2 19.5 0.619 E1 5 4.2 19.2 0.627 E1 10 4.2 19.3 0.628 E1 20 4.3 19.5 0.628 E2 5 4.2 19.0 0.626 E2 10 4.2 19.1 0.626 E2 20 4.2 19.3 0.626

[0206] In comparison with state-of-art nitrile compounds PD1 and PD2, alternative dopants E1, E2 and C.sub.60F.sub.48 enable comparable efficiency at lower operational voltage or higher efficiency at comparable voltage. [0207] 2) Yellow phosphorescent OLED comprising the second hole injection layer p-doped with a fluorinated metal complex or with fluorinated fullerene compound

[0208] Table 2a schematically describes the model device.

TABLE-US-00003 TABLE 2a c d Material [vol %] [nm] ITO 100 90 F1:PD2 92:8 10 F1 100 145 F2:p-dopant (100 − x):x 10 F2 100 20 GHM020S:F4  90:10 40 F5 100 25 F6:Yb 99:1 10 Al 100 100

[0209] The results are given in Table 2b

TABLE-US-00004 TABLE 2b U EQE c (10 mA/cm.sup.2) (10 mA/cm.sup.2) p-dopant [vol %] [V] [%] CIE-y PD1 1 5.3 20.6 0.561 C.sub.60F.sub.48 1 5.0 20.8 0.561

[0210] In comparison with state-of-art nitrite compo d PD1, alternative dopant C.sub.60F.sub.48 enables higher efficiency at lower operational voltage.

[0211] The features disclosed in the foregoing description, in the claims and the accompanying drawings may, both separately or in any combination be material for realizing the invention in diverse forms thereof.

[0212] Key symbols and abbreviations used throughout the application:

[0213] CV cyclic voltammetry

[0214] DSC differential scanning calorimentry

[0215] EBL electron blocking layer

[0216] EIL electron injecting layer

[0217] EML emitting layer

[0218] eq. equivalent

[0219] ETL electron transport layer

[0220] ETM electron transport matrix

[0221] Fc ferrocene

[0222] Fc+ ferricenium

[0223] HBL hole blocking layer

[0224] HIL hole injecting layer

[0225] HOMO highest occupied molecular orbital

[0226] HPLC high performance liquid chromatography

[0227] HTL hole transport layer

[0228] p-HTL p-doped hole transport layer

[0229] HTM hole transport matrix

[0230] ITO indium tin oxide

[0231] LUMO lowest unoccupied molecular orbital

[0232] mol % molar percent

[0233] NMR nuclear magnetic resonance

[0234] OLED organic light emitting diode

[0235] OPV organic photovoltaics

[0236] PTFE polytetrafluoroethylene

[0237] QE quantum efficiency

[0238] R.sub.f retardation factor in TLC

[0239] RGB red-green-blue

[0240] TCO transparent conductive oxide

[0241] TFT thin film transistor

[0242] T.sub.g glass transition temperature

[0243] TLC thin layer chromatography

[0244] vacuum thermal evaporation

[0245] wt % weight percent