Organic electroluminescent device

1. An organic electroluminescent device comprising:

a cathode;

an anode;

at least one emitting layer arranged between the cathode and the anode;

at least one hole-transport layer arranged between the anode and the at least one emitting layer; and

at least one hole-injection layer arranged between the anode and the at least one hole-transport layer,

where the at least one hole-injection layer comprises at least 90% by weight, based on the total weight of the hole-injection layer, of at least one bismuth or gallium complex, and

where the reduction potential of the bismuth or gallium complex is higher than or equal to −3.5 V and lower than or equal to 0.5 V vs. Fc/Fc + , determined by cyclic voltammetry.

2. The organic electroluminescent device according to claim 1 , wherein the reduction potential of the bismuth or gallium complex is higher than or equal to −3.0 V and lower than or equal to 0 V vs. Fc/Fc + .

3. The organic electroluminescent device according to claim 1 , wherein the hole-injection layer has a thickness of from 0.5 to 50 nm.

4. The organic electroluminescent device according to claim 1 , wherein the hole-injection layer has a thickness of from 1 to 5 nm.

5. The organic electroluminescent device according to claim 1 , wherein the hole-injection layer is adjacent to the anode on the anode side and adjacent to the hole-transport layer on the cathode side.

6. The organic electroluminescent device according to claim 1 , wherein the metal complex is a bismuth complex comprising a ligand of the following structure:

where

R 11 and R 12 are selected, identically or differently, from the group consisting of O, S, Se, NH and NR 14 , where R 14 is an alkyl or aryl group; where R 14 and R 13 may form a ring with one other; and

R 13 is selected from the group consisting of a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms, an alkenyl or alkinyl group having 2 to 40 C atoms, a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH 2 groups may be replaced by RC═CR, C≡C, Si(R) 2 , C═O, C═S, C═NR, P(═O)(R), SO, SO 2 , NR, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I or CN, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R, an aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, and a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which may be substituted by one or more radicals R; where R 13 may form a ring with at least one of the radical R 12 ; and

R is on each occurrence, identically or differently, H, D, For, a straight-chain alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, where one or more H atoms in the straight-chain, branched or cyclic alkyl groups may be replaced by F, an aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms, in which one or more H atoms in the aromatic or heteroaromatic ring system may be replaced by F; where two or more substituents R may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another.

7. The organic electroluminescent device according to claim 1 , wherein the bismuth complex is selected from bismuth (III) acetates and bismuth (III) benzoates.

8. The organic electroluminescent device according to claim 1 , wherein the bismuth complex corresponds to a complex of the Formula (P-1):

where

R is on each occurrence, identically or differently, H, D, F or, a straight-chain alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms, where one or more H atoms in the straight-chain, branched or cyclic alkyl groups may be replaced by F, an aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms, in which one or more H atoms in the aromatic or heteroaromatic ring system may be replaced by F; where two or more substituents R may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another.

9. The organic electroluminescent device according to claim 1 , wherein the at least one hole-transport layer comprises at least one triarylamine.

10. The organic electroluminescent device according to claim 1 , wherein the at least one hole-transport layer comprises at least one triarylamine, which corresponds to a compound of Formula (1) or to a polymer comprising at least one structural unit of the Formula (2):

where

A 1 is on each occurrence, identically or differently, a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 1 ;

R 1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 2 ) 2 , CN, NO 2 , Si(R 2 ) 3 , B(OR 2 ) 2 , C(═O)R 2 , P(═O)(R 2 ) 2 , S(═O)R 2 , S(═O) 2 R 2 , OSO 2 R 2 , a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R 2 , where one or more non-adjacent CH 2 groups may be replaced by R 2 C═CR 2 , C≡C, Si(R 2 ) 2 , C═O, C═S, C═NR 2 , P(═O)(R 2 ), SO, SO 2 , NR 2 , O, S or CONR 2 and where one or more H atoms may be replaced by D, F, Cl, Br, I or CN, or a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2 , or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or an aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 2 , where two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

R 2 is on each occurrence, identically or differently, H, D, F or an aliphatic hydrocarbon radical having 1 to 20 C atoms, an aromatic and/or a heteroaromatic hydrocarbon radical having 5 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by F; where two or more substituents R 2 may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; and

the dashed lines in Formula (2) represent bonds to adjacent structural limits in the polymer.

11. The organic electroluminescent device according to claim 1 , wherein the at least one hole-transport layer comprises at least one monotriarylamine, which corresponds to a compound of one of the Formulae (T-1) to (T-7),

wherein

Ar 1 is on each occurrence, identically or differently, a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 1 ;

Z is on each occurrence, identically or differently, N or CR 1 , where Z is equal to C if a substituent is bonded;

X and Y are on each occurrence, identically or differently, a single bond, O, S, Se, BR 1 , C(R 1 ) 2 , Si(R 1 ) 2 , NR 1 , PR 1 , C(R 1 ) 2 —C(R 1 ) 2 or CR 1 ═CR 1 ;

E is O, S, Se, BR 1 , C(R 1 ) 2 , Si(R 1 ) 2 , NR 1 , PR 1 , C(R 1 ) 2 —C(R 1 ) 2 or CR 1 ═CR 1 ;

R 1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 2 ) 2 , CN, NO 2 , Si(R 2 ) 3 , B(OR 2 ) 2 , C(═O)R 2 , P(═O)(R 2 ) 2 , S(═O)R 2 , S(═O) 2 R 2 , OSO 2 R 2 , a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R 2 , where one or more non-adjacent CH 2 groups may be replaced by R 2 C═CR 2 , C≡C, Si(R 2 ) 2 , C═O, C═S, C═NR 2 , P(═O)(R 2 ), SO, SO 2 , NR 2 , O, S or CONR 2 and where one or more H atoms may be replaced by D, F, Cl, Br, I or CN, or a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2 , or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or an aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or a diarylamino group, dihtteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 2 , where two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

R 2 is on each occurrence, identically or differently, H, D, F or an aliphatic hydrocarbon radical having 1 to 20 C atoms, an aromatic and/or a heteroaromatic hydrocarbon radical having 5 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by F; where two or more substituents R 2 may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

i is on each occurrence, identically or differently, 0 or 1, where the sum of all i is at least equal to 1;

p is equal to 0 or 1;

m and n are, identically or differently, 0 or 1, where the sum of m and n is equal to 1 or 2.

12. The organic electroluminescent device according to claim 1 , wherein the at least one hole-transport layer comprises at least one monotriarylamine, which corresponds to a compound of one of the Formulae (T-2-1) to (T-2-4),

wherein

Ar 1 is on each occurrence, identically or differently, a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 1 ;

Z is on each occurrence, identically or differently, N or CR 1 , where Z is equal to C if a substituent is bonded;

X is on each occurrence, identically or differently, a single bond, O, S, Se, BR 1 , C(R 1 ) 2 , Si(R 1 ) 2 , NR 1 , PR 1 , C(R 1 ) 2 —C(R 1 ) 2 or CR 1 ═CR 1 ;

R 1 is on each occurrence, identically or differently, H, D, F, Cl, Br, I, N(R 2 ) 2 , CN, NO 2 , Si(R 2 ) 3 , B(OR 2 ) 2 , C(═O)R 2 , P(═O)(R 2 ) 2 , S(═O)R 2 , S(═O) 2 R 2 , OSO 2 R 2 , a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 C atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R 2 , where one or more non-adjacent CH2 groups may be replaced by R 2 C═CR 2 , C≡C, Si(R 2 ) 2 , C═O, C═S, C═NR 2 , P(═O)(R 2 ), SO, SO 2 , NR 2 , O, S or CONR 2 and where one or more H atoms may be replaced by D, F, Cl, Br, I or CN, or a mono- or polycyclic, aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R 2 , or an aryloxy or heteroaryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or an aralkyl or heteroaralkyl group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R 2 , or a diarylamino group, diheteroarylamino group or arylheteroarylamino group having 10 to 40 aromatic ring atoms, which may be substituted by one or more radicals R 2 , where two or more radicals R 1 here may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another;

R 2 is on each occurrence, identically or differently, H, D, F or an aliphatic hydrocarbon radical having 1 to 20 C atoms, an aromatic and/or a heteroaromatic hydrocarbon radical having 5 to 20 C atoms, in which, in addition, one or more H atoms may be replaced by F; where two or more substituents R 2 may also form a mono- or polycyclic, aliphatic or aromatic ring system with one another; and

p is equal to 0 or 1.

13. The organic electroluminescent device according to claim 12 , wherein the at least one monotriarylamine corresponds to a compound of formula (T-2-1).

14. The organic electroluminescent device according to claim 11 , wherein X is a single bond and Z is C(R 1 ) 2 .

15. A method for producing the organic electroluminescent device according to claim 1 comprising the following steps:

a. Depositing a hole-injection layer comprising at least 90% by weight, based on the total weight of the hole-injection layer, of at least one bismuth complex or gallium complex on an anode;

b. Depositing at least one hole-transport layer on the hole-injection layer;

c. Depositing at least one emitting layer;

d. Forming a cathode.

16. A method according to claim 15 , wherein the hole-injection layer, the hole-transport layer and the emitting layer are deposited, differently or identically, via a vapour deposition process and/or a solution-based process.

17. The organic electroluminescent device according to claim 1 , wherein the bismuth or gallium complexes are selected from the group consisting of