Metal Amides for Use as HIL for an Organic Light-Emitting Diode (OLED)

Abstract

The present invention relates to metal amides of general Formula Ia and for their use as hole injection layer (HIL) for an Organic light-emitting diode (OLED), and a method of manufacturing Organic light-emitting diode (OLED) comprising an hole injection layer containing a metal amide of general Formula Ia:

##STR00001##

Claims

1. An OLED comprising: an anode, a hole injection layer, and a hole transport layer, wherein the hole injection layer is in direct contact with the anode and the hole transport layer is in direct contact with the hole injection layer; and the hole injection layer has a composition that is different than a composition of the hole transport layer, wherein the hole injection layer comprises a charge neutral metal amide compound, wherein the charge neutral metal amide compound has the Formula Ia: ##STR00203## wherein: G=halide, O, alkoxylate or amine of Formula IIa to IIe: ##STR00204## R.sup.1 to R.sup.5 are independently selected from the group consisting of H, C.sub.1 to C.sub.20 alkyl, C.sub.1 to C.sub.20 heteroalkyl, unsubstituted or C.sub.1 to C.sub.12 substituted C.sub.6 to C.sub.20 aryl, unsubstituted or C.sub.1 to C.sub.12 substituted heteroaryl with 5 to 20 ring-forming atoms, halogenated or perhalogenated C.sub.1 to C.sub.20 alkyl, halogenated or perhalogenated C.sub.1 to C.sub.20 heteroalkyl, halogenated or perhalogenated C.sub.6 to C.sub.20 aryl, and halogenated or perhalogenated heteroaryl with 5 to 20 ring-forming atoms; or at least one R.sup.1 and R.sup.4 and/or R.sup.2 and R.sup.3 and/or R.sup.1 and R.sup.5 are bridged and form a 5 to 20 member ring; m=0, 1, 2, 3 or 4; M=a metal selected from the group consisting of alkali metal, alkaline earth metal, Al, Ga, In, Sn(II), Sn(IV), Pb(II), transition metal, and rare earth metal; wherein the bond between N and the metal M is a covalent bond or N forms a non-covalent interaction to the metal M; L=charge neutral ligand which coordinates to the metal M, selected from the group consisting of H.sub.2O, C.sub.2 to C.sub.40 mono- or multi-dentate ethers and C.sub.2 to C.sub.40 thioethers, C.sub.2 to C.sub.40 amines, C.sub.2 to C.sub.40 phosphine, C.sub.2 to C.sub.20 alkyl nitrile or C.sub.2 to C.sub.40 aryl nitrile, and a compound according to Formula (III); ##STR00205## wherein R.sup.6 and R.sup.7 are independently selected from C.sub.1 to C.sub.20 alkyl, C.sub.1 to C.sub.20 heteroalkyl, C.sub.6 to C.sub.20 aryl, heteroaryl with 5 to 20 ring-forming atoms, halogenated or perhalogenated C.sub.1 to C.sub.20 alkyl, halogenated or perhalogenated C.sub.1 to C.sub.20 heteroalkyl, halogenated or perhalogenated C.sub.6 to C.sub.20 aryl, halogenated or perhalogenated heteroaryl with 5 to 20 ring-forming atoms, or at least one R.sup.6 and R.sup.7 are bridged and form a 5 to 20 member ring, or the two R.sup.6 and/or the two R.sup.7 are bridged and form a 5 to 40 member ring or form a 5 to 40 member ring comprising an unsubstituted or C.sub.1 to C.sub.12 substituted phenanthroline; p=0, 1, 2 or 3; A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are independently selected from CO, SO.sub.2 or POR.sup.8; R.sup.8=electron withdrawing group selected from the group consisting of halide, nitrile, halogenated or perhalogenated C.sub.1 to C.sub.20 alkyl, halogenated or perhalogenated C.sub.6 to C.sub.20 aryl, and halogenated or perhalogenated heteroaryl with 5 to 20 ring-forming atoms; n=1, 2, 3, 4 or 5; B.sup.1, B.sup.2, B.sup.3 and B.sup.4 are same or independently selected from substituted or unsubstituted C.sub.1 to C.sub.20 alkyl, substituted or unsubstituted C.sub.1 to C.sub.20 heteroalkyl, substituted or unsubstituted C.sub.6 to C.sub.20 aryl, substituted or unsubstituted C.sub.5 to C.sub.20 heteroaryl, or B.sup.1 and B.sup.2 are bridged; wherein B.sup.1 and B.sup.2 are bridged, then: M, N, A.sup.1, B.sup.1, B.sup.2, A.sup.2 and N form a 7 to 10 member ring according to Formula Ib; ##STR00206## or N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a 5 to 10 member ring according to Formula Ic, ##STR00207## or N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a first 5 to 10 member ring and B.sup.1 and B.sup.2 form a second 5 to 20 member ring according to Formula Id: ##STR00208## and optionally the hole transport layer further comprises a triarylamine compound having the Formula VIIa: ##STR00209## wherein: Ar.sup.1 and Ar.sup.2=independently selected from substituted or unsubstituted C.sub.6 to C.sub.20 arylene; Ar.sup.3 and Ar.sup.4=independently selected from substituted or unsubstituted C.sub.6 to C.sub.20 aryl; Ar.sup.3 and Ar.sup.4=independently selected from substituted or unsubstituted C.sub.6 to C.sub.20 aryl or C.sub.2 to C.sub.40 heteroaryl; R.sup.9=a single chemical bond, an unsubstituted or substituted C.sub.1 to C.sub.6 alkyl and unsubstituted or substituted C.sub.1 to C.sub.5 heteroalkyl; q=0, 1 or 2; r=0 or 1; wherein the substituents for Ar.sup.1 to Ar.sup.6 are independently selected from C.sub.1 to C.sub.20 alkyl, C.sub.1 to C.sub.20 heteroalkyl, or halide; and the substitutents for R.sup.9 are independently selected from C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.5 heteroalkyl, C.sub.6 to C.sub.20 aryl and C.sub.5 to C.sub.20 heteroaryl.

2. The OLED according to claim 1, wherein the charge neutral metal amide compound has the Formula Ia, ##STR00210## wherein: A.sup.1 and A.sup.2 are the same or independently selected from CO, POR.sup.8, or SO.sub.2; or A.sup.1 and A.sup.2 are independently selected from CO, POR.sup.8, or SO.sub.2, and N, A.sup.1, B.sup.1, A.sup.2 and B.sup.2 form a 5 to 10 member ring.

3. The OLED according to claim 1, wherein for: p=0, m=1, 2, 3 or 4 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IIa: ##STR00211## or p=1, 2 or 3, and n=1, 2, 3 or 4 and m=0, the charge neutral metal amide compound has the Formula IIb: ##STR00212## or p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula IIc: ##STR00213## or p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a first 5 to 10 member ring and B.sup.1 and B.sup.2 are bridged to form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula IId: ##STR00214## or p=1, 2 or 3, n=2, m=1, 2, 3 or 4, and M, N, A.sup.1, B.sup.1, B.sup.2, A.sup.2 and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula IIe: ##STR00215## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula IIf: ##STR00216## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, A.sup.1, B.sup.1, B.sup.2 and A.sup.2 form a first 5 to 10 member ring, and B.sup.1 and B.sup.2 are bridged to form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula IIg: ##STR00217## p=1, 2 or 3, n=2, m=0 and M, N, A.sup.1, B.sup.1, B.sup.2, A.sup.2 and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula IIh: ##STR00218##

4. The OLED according to claim 1, wherein for A.sup.1 and A.sup.2 are SO.sub.2: p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IIIa: ##STR00219## p=0, n=1, 2, 3 or 4, m=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IIIb: ##STR00220## p=1, 2 or 3, n=1, 2, 3 or 4, m=0, the charge neutral metal amide compound has the Formula IIIc: ##STR00221## p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, SO.sub.2, B.sup.1, B.sup.2 and SO.sub.2 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula IIId: ##STR00222## p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, SO.sub.2, B.sup.1, B.sup.2 and SO.sub.2 form a first 5 to 10 member ring, and B.sup.1 and B.sup.2 are bridged to form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula IIIe: ##STR00223## p=1, 2 or 3, n=2, m=1, 2, 3 or 4 and M, N, SO.sub.2, B.sup.1, B.sup.2, SO.sub.2 and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula IIIf: ##STR00224## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, SO.sub.2, B.sup.1, B.sup.2 and SO.sub.2 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula IIIg: ##STR00225## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, SO2, B.sup.1, B.sup.2 and SO.sub.2 form a first 5 to 10 member ring, and B.sup.1 and B.sup.2 are bridged to form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula IIIb: ##STR00226## p=1, 2 or 3, n=2, m=0 and M, N, SO.sub.2,B.sup.1,B.sup.2, SO.sub.2 and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula IIIi: ##STR00227## wherein for A.sup.1 and A.sup.2 are POR.sup.8: p=1, 2 or 3, m=1, 2, 3 or 4 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IVa: ##STR00228## p=0, m=1, 2, 3 or 4 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IVb: ##STR00229## p=1, 2 or 3, m=0 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula IVc: ##STR00230## p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, POR.sup.8, B.sup.1, B.sup.2 and POR.sup.8 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula (IVd): ##STR00231## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, POR.sup.8, B.sup.1, B.sup.2 and POR.sup.8 form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula (IVe): ##STR00232## wherein for A.sup.1 and A.sup.2 are CO: p=1, 2 or 3, m=1, 2, 3 or 4 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula Va: ##STR00233## p=0, n=1, 2, 3 or 4, m=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula Vb: ##STR00234## p=1, 2 or 3, n=1, 2, 3 or 4, m=0, the charge neutral metal amide compound has the Formula Vc: ##STR00235## p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, CO, B.sup.1, B.sup.2 and CO form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula Vd: ##STR00236## p=1, 2 or 3, n=1, 2, 3 or 4, m=1, 2, 3 or 4 and N, CO, B.sup.1, B.sup.2 and CO form a first 5 to 10 member ring, and B.sup.1 and B.sup.2 are bridged to form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula Ve: ##STR00237## p=1, 2 or 3, n=2, m=1, 2, 3 or 4 and M, N, CO, B.sup.1, B.sup.2, CO and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula Vf: ##STR00238## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, CO, B.sup.1, B.sup.2 and CO form a 5 to 10 member ring, the charge neutral metal amide compound has the Formula (Vg): ##STR00239## p=1, 2 or 3, n=1, 2, 3 or 4, m=0 and N, CO, B.sup.1, B.sup.2 and CO form a first 5 to 10 member ring, and B.sup.1 and B.sup.2 form a second 5 to 20 member ring, the charge neutral metal amide compound has the Formula Vh: ##STR00240## p=1, 2 or 3, n=2, m=0 and M, N, CO, B.sup.1, B.sup.2, CO and N form a 7 to 10 member ring, the charge neutral metal amide compound has the Formula (Vi): ##STR00241## or wherein for A.sup.1 is SO.sub.2 and A.sup.2 is POR.sup.8: p=1, 2 or 3, m=1, 2, 3 or 4 and n=1, 2, 3 or 4, the charge neutral metal amide compound has the Formula VIa: ##STR00242##

5. The OLED according to claim 1, wherein B.sup.1, B.sup.2, B.sup.3 and B.sup.4 are independently selected from a substituted C.sub.1 to C.sub.20 alkyl, substituted C.sub.1 to C.sub.20 heteroalkyl, substituted C.sub.6 to C.sub.20 aryl, or substituted C.sub.5 to C.sub.20 heteroaryl; wherein the substituent is an electron withdrawing group selected from the group consisting of a halide, nitrile, perhalogenated C.sub.1 to C.sub.20 alkyl, perhalogenated C.sub.6 to C.sub.20 aryl, and perhalogenated heteroaryl with 6 to 20 ring-forming atoms.

6. The OLED according to claim 1, wherein m=0, 1 or 2.

7. The OLED according to claim 1, wherein M is selected from Li(I), Na(I), K(I), Cs(I), Mg(II), Ca(II), Sr(II), Ba(II), Sc(III), Y(III), Ti(IV), V(III-V), Cr(III-VI), Mn(II), Mn(III), Fe(II), Fe(III), Co(II), Co(III), Ni(II), Cu(I), Cu(II), Zn(II), Ag(I), Au(I), Au(III), Al(III), Ga(III), In(III), Sn(II), Sn(IV), or Pb(II).

8. The OLED according to claim 1, wherein the charge neutral metal amide compound has the Formula Ib: ##STR00243## wherein A.sup.3 and A.sup.4 are same or independently selected from CO, POR.sup.8, or SO.sub.2; B.sup.3 and B.sup.4 are independently selected from substituted or unsubstituted C.sub.1 to C.sub.20 alkyl, substituted or unsubstituted C.sub.1 to C.sub.20 heteroalkyl, substituted or unsubstituted C.sub.6 to C.sub.20 aryl, or substituted or unsubstituted C.sub.6 to C.sub.20 heteroaryl; and M, N, A.sup.1, B.sup.1, A.sup.2 and B.sup.2 form a 7 to 10 member ring.

9. The OLED according to claim 1, wherein N, A.sup.1, B.sup.1, A.sup.2 and B.sup.2 form a first 5 to 10 member ring and B.sup.1 and B.sup.2 according to Formula Id: ##STR00244## are bridged to form a second ring of a substituted or unsubstituted C.sub.6 to C.sub.20 aryl, or of a substituted or unsubstituted C.sub.6 to C.sub.20 heteroaryl ring.

10. The OLED according to claim 1, wherein the charge neutral metal amide compound is selected from at least one of the fluorinated compounds according to Formula C1 to C25: wherein Formula C1 to C16, wherein p=0, m=0, n=1, 2, 3 or 4 and A.sup.1 and A.sup.2 are SO.sub.2: ##STR00245## ##STR00246## Formula C17 to C23, wherein n=1, 2, 3 or 4, A.sup.1 and A.sup.2 are CO: ##STR00247## Formula C24 to C25, wherein n=1, 2, 3 or 4, A.sup.1 and A.sup.2 are POR.sup.8: ##STR00248##

11. The OLED according to claim 1, wherein the charge neutral metal amide compound is selected from at least one fluorinated compound according to Formula D1 to D24: wherein p=0, m=0, n=1, 2, 3 or 4 and A.sup.1 and A.sup.2 are SO.sub.2: ##STR00249## ##STR00250## ##STR00251## ##STR00252##

12. The OLED according to claim 1, wherein the charge neutral metal amide compound is selected from at least one fluorinated compound according to Formula F1 to F23: wherein the charge neutral ligand L coordinates to the metal M: ##STR00253## ##STR00254## ##STR00255## ##STR00256## wherein R.sup.6 and R.sup.7 are independently selected from C.sub.1 to C.sub.20 alkyl, C.sub.1 to C.sub.20 heteroalkyl, C.sub.6 to C.sub.20 aryl, heteroaryl with 5 to 20 ring-forming atoms, halogenated or perhalogenated C.sub.1 to C.sub.20 alkyl, halogenated or perhalogenated C.sub.1 to C.sub.20 heteroalkyl, halogenated or perhalogenated C.sub.6 to C.sub.20 aryl, halogenated or perhalogenated heteroaryl with 5 to 20 ring-forming atoms, or at least one R.sup.6 and R.sup.7 are bridged and form a 5 to 20 member ring, or the two R.sup.6 and/or the two R.sup.7 are bridged and form a 5 to 40 member ring or form a 5 to 40 member ring comprising an unsubstituted or C.sub.1 to C.sub.12 substituted phenanthroline.

13. The OLED according to claim 1, wherein the charge neutral metal amide compound is selected from at least one fluorinated compound according to Formula F24 to F46: wherein a halide, O, alkoxylate or amine bonds to the metal M: ##STR00257## ##STR00258## ##STR00259## ##STR00260## wherein R.sup.1 to R.sup.5 are independently selected from the group comprising H, C.sub.1 to C.sub.20 alkyl, C.sub.1 to C.sub.20 heteroalkyl, unsubstituted or C.sub.1 to C.sub.12 substituted C.sub.6 to C.sub.20 aryl, unsubstituted or C.sub.1 to C.sub.12 substituted heteroaryl with 5 to 20 ring-forming atoms, halogenated or perhalogenated C.sub.1 to C.sub.20 alkyl, halogenated or perhalogenated C.sub.1 to C.sub.20 heteroalkyl, halogenated or perhalogenated C.sub.6 to C.sub.20 aryl, halogenated or perhalogenated heteroaryl with 5 to 20 ring-forming atoms; or at least one R.sup.1 and R.sup.4 and/or R.sup.2 and R.sup.3 and/or R.sup.1 and R.sup.5 are bridged and form a 5 to 20 member cyclic ring.

14. The OLED according to claim 1, wherein the Ar.sup.1 and Ar.sup.2 of Formula VIIa are independently selected from phenylene, biphenylene, naphthylene, anthranylene, carbazolylene, or fluorenylene.

15. The OLED according to claim 14, wherein the Ar.sup.1 and Ar.sup.2 of Formula VIIa are independently selected from phenylene or biphenylene.

16. The OLED according claim 1, wherein the Ar.sup.3 to Ar.sup.6 of Formula VIIa are independently selected from phenyl, biphenyl, terphenyl, quartphenyl, fluorenyl, napthyl, anthranyl, phenanthryl, thiophenyl, fluorenyl, or carbazolyl.

17. The OLED according to claim 1, wherein the hole transport layer comprises a triarylamine compound of Formula VIIa, wherein Ar.sup.1 and Ar.sup.2 are independently selected from phenyl or biphenyl; Ar.sup.3 to Ar.sup.6 are selected from phenyl, tolyl, xylyl, mesityl, biphenyl, 1-naphthyl, 2-napthyl, 2-(9,9-dialkyl-fluorenyl), 2-(9-alkyl-9′-aryl-fluorenyl) or 2-(9,9-diaryl-fluorenyl); R.sup.9=single bond; r=1 and q=1.

18. The OLED according to claim 1, wherein the hole transport layer comprises a triarylamine compound of Formula VIIa, wherein Ar.sup.1 is phenyl; Ar.sup.3 to Ar.sup.6 are selected from phenyl, tolyl, xylyl, mesityl, biphenyl, 1-naphthyl, 2-napthyl, 2-(9,9-dialkyl-fluorenyl), 2-(9-alkyl-9′-aryl-fluorenyl) or 2-(9,9-diaryl-fluorenyl); R.sup.9=single bond; r=0 and q=1.

19. The OLED according to claim 1, wherein the hole transport layer comprises a triarylamine compound of Formula VIIa, wherein N, Ar.sup.1 and Ar.sup.3 form a carbazole ring; Ar.sup.2 is phenyl or biphenyl; Ar.sup.3 to Ar.sup.6 are selected from phenyl, tolyl, xylyl, mesityl, biphenyl, 1-naphthyl, 2-napthyl, 2-(9,9-dialkyl-fluorenyl), 2-(9-alkyl-9′-aryl-fluorenyl) or 2-(9,9-diaryl-fluorenyl); R.sup.9=single bond; r=1 and q=1.

20. The OLED according to claim 18, wherein a substituent on Ar.sup.1 is selected from phenyl, biphenyl, 2-(9,9-dialkyl-fluorenyl), 2-(9-alkyl-9′-aryl-fluorenyl) and 2-(9,9-diaryl-fluorenyl).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0395] 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:

[0396] FIG. 1 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0397] FIG. 2 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0398] FIG. 3 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0399] FIG. 4 is an overview of metal amides based on general Formula Ia that can be used according to the invention.

[0400] FIG. 5 is an overview of metal amides that can be used according to the invention with specific A1 and A2, wherein A1 and A2 are SO2.

[0401] FIG. 6 is an overview of metal amides that can be used according to the invention with specific A1 and A2, wherein A1 and A2 are POR8.

[0402] FIG. 7 is an overview of metal amides that can be used according to the invention with specific A1 and A2, wherein A1 and A2 are CO.

[0403] FIG. 8 is an overview of metal amides that can be used according to the invention with specific A1 and A2, wherein A1 and A2 are selected different, wherein A1 is SO.sub.2 and A2 is POR8.

DETAILED DESCRIPTION

[0404] 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.

[0405] 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.

[0406] 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 a substrate 110. On the substrate 110 an anode 120 is disposed. On the anode 120 a hole injection layer 130 containing or consisting of a metal amide compound according to the invention is disposed and thereon a hole transport layer 140. Onto the hole transport layer 140 an emission layer 150 and an cathode electrode 190, exactly in this order, are disposed.

[0407] FIG. 2 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 a substrate 110, a first electrode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 161. The electron transport layer (ETL) 161 is formed directly on the EML 150. Onto the electron transport layer (ETL) 161 a cathode electrode 190 is disposed.

[0408] Instead of a single electron transport layer 161, optional an electron transport layer stack (ETL) can be used.

[0409] FIG. 3 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 comprises a hole blocking layer (HBL) 155 and an electron injection layer (E1L) 180.

[0410] Referring to FIG. 3 the OLED 100 includes a substrate 110, an anode electrode 120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 161, an electron injection layer (EIL) 180 and a cathode electrode 190. The layers are disposed exactly in the order as mentioned before.

[0411] In the description above the method of manufacture an OLED of the present invention is started with a substrate 110 onto which an anode electrode 120 is formed, on the anode electrode 120, an hole injection layer 130, hole transport layer 140, an emission layer 150, optional a hole blocking layer 155, optional at least one electron transport layer 161, optional at least one electron injection layer 180, and a cathode electrode 190 are formed, exactly in that order or exactly the other way around.

[0412] 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. In addition, various other modifications may be applied thereto.

[0413] 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.

EXAMPLES

General Procedure

[0414] For bottom emission devices, a 15 Ω/cm.sup.2 glass substrate (available from Corning Co.) with 100 nm ITO was cut to a size of 50 mm×50 mm×0.7 mm, ultrasonically washed with isopropyl alcohol for 5 minutes and then with pure water for 5 minutes, and washed again with UV ozone for 30 minutes, to prepare a first electrode. For top emission devices, the anode electrode was formed from 100 nm silver on glass which was prepared by the same methods as described above.

[0415] Then, the hole injection layer according to the examples of Table 6 was vacuum deposited on the ITO electrode, to form a HIL having a thickness according to the examples of table 6. Then the corresponding hole injection layer according to the examples of table 6 was vacuum deposited on the HIL, to form a HTL having a thickness as mentioned in table 6, respectively.

[0416] The wt.-% of the HIL-material and HTL can be taken from Tables 6 below, whereby the wt.-% amount of the HIL-material is 100 wt.-% and of the HTL-material is 100 wt.-%, if no not indicated otherwise indicated in Table 6, respectively. That means that the HIL according to examples 1 to 8 consist of the metal amide compound according to the invention. Further the HIL according to examples 1 to 8 consist of one compound only, as mentioned in Table 6. However, the hole injection layer may comprises traces of the compound of the hole transport layer, due to the process of manufacture. For example, the HIL may form islands, in other words not a continuous layer. Therefore, when the HTL is deposited on top, HTL may be deposited in the same plane as the HIL. In reverse engineering, this layer may appear like a mixed layer, even though one compound was deposited after the other.

[0417] The comparative example 4 the hole injection layer comprises a mixture of a triarylamine T-3: Li TFSI in a ratio of 98:2 wt.-%.

[0418] 97 wt.-% of ABH113 (Sun Fine Chemicals) as a host and 3 wt.-% of NUBD370 (Sun Fine Chemicals) as a dopant were deposited on the HTL, to form a blue-emitting EML with a thickness of 20 nm.

[0419] Then the ETL-layer of matrix compound of 50 wt.-% MX 1 and 50 wt.-% LiQ (50 wt.-%:50 wt.-%) having a thickness of 36 nm is formed by deposing the matrix compound from a first deposition source and the lithium organic complex or lithium halide from a second deposition source directly on the EML.

[0420] For the comparative examples 1 to 6 and examples 1 to 8 only one electron transport layer is formed.

[0421] The cathode was evaporated at ultra-high vacuum of 10-7 bar. Therefore, a thermal single co-evaporation of one or several metals was performed with a rate of 0, 1 to 10 nm/s (0.01 to 1 Å/s) in order to generate a homogeneous cathode with a thickness of 5 to 1000 nm. For top emission devices, the cathode electrode was formed from 13 nm magnesium (90 vol.-%)-silver (10 vol.-%) alloy. For bottom emission devices, the cathode electrode was formed from 100 nm aluminum.

[0422] The OLED stack is protected from ambient conditions by encapsulation of the device with a glass slide. Thereby, a cavity is formed, which includes a getter material for further protection.

[0423] To assess the performance of the inventive examples compared to the prior art, the current efficiency is measured under ambient conditions (20° C.). Current voltage measurements are performed using a Keithley 2400 sourcemeter, and recorded in V. At 10 mA/cm.sup.2 for bottom emission and 15 mA/cm.sup.2 for top emission devices, a calibrated spectrometer CAS140 from Instrument Systems is used for measurement of CIE coordinates and brightness in Candela. Lifetime LT of the device is measured at ambient conditions (20° C.) and 15 mA/cm.sup.2, using a Keithley 2400 sourcemeter, and recorded in hours. The brightness of the device is measured using a calibrated photo diode. The lifetime LT is defined as the time till the brightness of the device is reduced to 97% of its initial value.

[0424] In bottom emission devices, the emission is predominately Lambertian and quantified in percent external quantum efficiency (EQE). To determine the efficiency EQE in % the light output of the device is measured using a calibrated photodiode at 10 mA/cm.sup.2.

[0425] In top emission devices, the emission is forward directed, non-Lambertian and also highly dependent on the mirco-cavity. Therefore, the efficiency EQE will be higher compared to bottom emission devices. To determine the efficiency EQE in % the light output of the device is measured using a calibrated photodiode at 15 mA/cm.sup.2.

Technical Effect of the Invention

Bottom Emission Devices

Effect of the Metal Cation on Device Performance

[0426] In Table 6 are shown device data for bottom emission devices. In comparative example 1, no hole injection layer is used. The voltage is high and rises rapidly during stability test, therefore lifetime has not been determined.

[0427] In comparative examples 2 and 3, the compound CNHAT has been used as hole injection layer. Two thicknesses have been tested, 3 nm and 10 nm. At 3 nm, the voltage is high and the device show a large voltage rise during lifetime test due to degradation. At 10 nm of dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (CNHAT (CAS 105598-27-4)) having the Formula A, which is typically used as hole injection layer, the voltage is reduced to 5.4 V, the EQE is 5%, and the voltage increase during degradation is within the range suitable for commercial applications. A voltage increase of no more than 0.2 V over 50 h at 15 mA/cm.sup.2 is considered acceptable.

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[0428] In comparative example 4, a 10 nm layer of triarylamine T-3, doped with 2 wt.-% Li TFSI is tested. The voltage is lower compared to comparative examples 1 to 3 and the efficiency EQE is comparable. However, the voltage stability is very poor. The voltage increases by 0.56 V after 50 h driving at 15 mA/cm.sup.2.

[0429] In Example 1 to 10, various metal amide compounds have been tested at 3 nm and 10 nm thickness. 3 nm Li TFSI offers the highest EQE at the lowest voltage, see example 1. The voltage is lower compared to comparative example 3, while the EQE is comparable. Similarly low voltages are achieved for 3 nm Mg (TFSI).sub.2, 3 nm Mn (TFSI).sub.2, 3 nm Li (cTFSI) and 10 nm Ag TFSI. In general, 3 nm metal amide gives better performance than 10 nm.

Effect of the HOMO Level of the Hole Transport Layer on Device Performance

[0430] In order to achieve light output in different colours, a large variety of materials is available for application in the emission layer of OLEDs. Each emission layer composition comes with different demands on the HTL (for example band-gap or triplet level). Therefore, the HTL materials of different OLEDs may differ in their HOMO level. Consequently, a good hole injection layer enables hole injection in to a large variety of HTL materials.

[0431] In a second step, triarylamine compounds with various HOMO levels are tested in the hole transport layer. HTLs which show low performance with the fluorescent blue EML used here may show unique performance with a different EML composition, for example phosphorescent blue or green EML, or for TADF (thermally activated delayed fluorescence) emitters. In the following examples, the hole injection performance is evaluated relative to CNHAT which is not suitable for injection into deep HOMO HTLs. For ease of comparison, 3 nm metal amide is used throughout. In the comparative examples, 10 nm CNHAT is used as hole injection layer.

[0432] For the shallowest HOMO triarylamine, T-3, 5.1 V and 4.6% EQE are achieved with Mg (TFSI)2 (Example 3). With deeper HOMO amines T-8 and T-9, the voltage remains constant at 5 V, while the efficiency varies between 3.8 and 5.2%. In particular for deeper HOMO triarylamines T-8 and T-9, much lower voltages are achieved with Mg (TFSI).sub.2 compared to CNHAT, see Examples 9 and 10 and comparative examples 5 and 6. The efficiency EQE remains in an acceptable range, independent of HOMO level of the hole transport layer.

[0433] The voltage stability of all examples is at an acceptable level, for example less than 0.35V over 50 hours stability test at 15 mA/cm.sup.2.

TABLE-US-00006 TABLE 6 Efficiency EQE dependency with respect to the variation of HOMO level of the hole transport layer EQE Hole Layer HTL V at 15 at 15 U(50 h)-U(0 h) injection thickness matrix mA/cm.sup.2 mA/cm.sup.2 at 15 mA/cm.sup.2 layer d (nm) compound (V) (%) [V] LT [h] Comparative — 0 T-3 6 6 >4.00 — example 1  Comparative CNHAT 3 T-3 6.5 5.2 0.57 — example 3  Comparative CNHAT 10 T-3 5.4 5 0.05 320 example 3  Comparative T-3: Li TFSI 10 T-3 5.2 5.1 0.56 — example 4  (98:2 wt.-%) Example 1  Li TFSI 3 T-3 5.1 5.1 0.12 84 Example 2  Li TFSI 10 T-3 >10.0 — — — Example 3  Mg (TFSI).sub.2 3 T-3 5.1 4.6 0.05 480 Example 4  Mg (TFSI).sub.2 10 T-3 5.6 4.7 0.04 470 Example 5  Ag TFSI 3 T-3 5 4.7 0.03 149 Example 6  Ag TFSI 10 T-3 5.3 5.1 0.09 30 Example 7  Mn (TFSI).sub.2 3 T-3 4.9 4.5 0.07 320 Example 8  Li (TFSI) 3 T-3 5.0 4.8 0.04 198 Comparative CNHAT 10 T-8 5.9 5.3 — — example 5  Example 9  Mg (TFSI).sub.2 3 T-8 5 4.8 0.07 190 Comparative CNHAT 10 T-9 8.7 5.9 — — example 6  Example 10 Mg (TFSI).sub.2 3 T-9 4.9 5.2 0.15 —

[0434] Another aspect is directed to an organic light-emitting diode (OLED) comprising more than one emission layer (EML) 150, for example two, three or four emission layers may be present. An organic light-emitting diode (OLED) comprising more than one emission layer is also described as a tandem OLED or stacked OLED.

[0435] Another aspect is directed to a device comprising at least one organic light-emitting diode (OLED). A device comprising organic light-emitting diodes (OLED) is for example a display or a lighting panel.

[0436] From the foregoing detailed description and examples, it will be evident that modifications and variations can be made to the compositions and methods of the invention without departing from the spirit and scope of the invention. Therefore, it is intended that all modifications made to the invention without departing from the spirit and scope of the invention come within the scope of the appended claims.