Bridged benzimidazole-carbene complexes and use thereof in OLEDS

1. A metal-carbene complex of formula (I):

wherein:

each R 1 is independently hydrogen, a linear or branched alkyl radical having 1 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical having 3 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and optionally bearing at least one functional group, a substituted or unsubstituted heteroaryl radical having a total of 5 to 18 carbon atoms and heteroatoms and optionally bears at least one functional group, or the two R 1 radicals, together with the carbon atom to which they are bonded, form a substituted or unsubstituted C 5 , C 6 , C 7 , or C 8 ring;

R 5 and R 6 together, or R 6 and R 7 together, form a unit of the formula:

wherein * denotes the connection to the carbon atoms of the benzene ring bearing the R 5 and R 6 radicals or R 6 and R 7 radicals, and the A is connected to the carbon atom bearing the R 5 , R 6 , or R 7 radical,

A is oxygen or sulfur;

R 2 is a linear or branched alkyl radical having 1 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical having 3 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and optionally bearing at least one functional group, a substituted or unsubstituted heteroaryl radical having a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bearing at least one functional group;

R 3 and R 4 are each independently a linear or branched alkyl radical having 1 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a cycloalkyl radical having 3 to 20 carbon atoms, which is optionally interrupted by at least one heteroatom and optionally bears at least one functional group, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and optionally bearing at least one functional group, a substituted or unsubstituted heteroaryl radical having a total of 5 to 18 carbon atoms and/or heteroatoms and optionally bearing at least one functional group;

R 8 is a linear or branched alkyl radical having 1 to 4 carbon atoms; and

m and n are each independently 0, 1, 2, or 3.

2. The metal-carbene complex of claim 1 , wherein, in formula (I):

each R 1 is independently a linear or branched alkyl radical having 1 to 10 carbon atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, or the two R1 radicals, together with the carbon atom to which they are bonded, form a substituted or unsubstituted C5 or C6 ring;

R 5 and R 6 together, or R 6 and R 7 together, form a unit of the formula:

wherein * denotes the connection to the carbon atoms of the benzene ring bearing the R 5 and R 6 radicals or R 6 and R 7 radicals, and the A is connected to the carbon atom bearing the R 5 , R 6 or R 7 radical;

A is oxygen or sulfur;

R 2 is an ortho,ortho′-disubstituted aryl radical having 6 to 30 carbon atoms;

R 3 and R 4 are each a linear or branched alkyl radical having 1 to 10 carbon atoms;

R 8 is a linear or branched alkyl radical having 1 to 4 carbon atoms; and

m and n are each independently 0, 1, or 2.

3. The metal-carbene complex of claim 1 , wherein, in formula (I):

each R 1 is independently a linear or branched alkyl radical having 1 to 4 carbon atoms;

R 6 and R 7 together form a unit of the formula:

wherein * denotes the connection to the carbon atoms of the benzene ring bearing the R 6 and R 7 radicals, and the oxygen atom is connected to the carbon atom bearing the R 7 radical;

R 2 is an ortho,ortho′-dialkylated phenyl radical;

R 3 and R 4 are each a linear or branched alkyl radical having 1 to 4 carbon atoms;

R 8 is a linear or branched alkyl radical having 1 to 4 carbon atoms; and

m and n are each independently 0, 1 or 2.

4. A light-emitting layer comprising a metal-carbene complex of claim 1 .

5. An organic light-emitting diode comprising a light-emitting layer of claim 4 .

6. A device selected from the group consisting of stationary visual display units, mobile visual display units, and illumination means, comprising an organic light-emitting diode of claim 5 .

7. A device selected from the group consisting of stationary visual display units, mobile visual display units, and illumination means, comprising a light-emitting layer of claim 4 .

8. An organic light-emitting diode comprising a metal-carbene complex of claim 1 , and at least one compound of the formula (V):

wherein:

X is NR, S, O, or PR, wherein R is aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl;

R 18 and R 19 are each independently alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, SiR 15 R 16 R 17 , a group B or a group with donor or acceptor action;

o is 0, 1, 2, 3, or 4;

p is 0, 1, 2, or 3;

B is —NR 20 R 21 , —P(O)R 22 R 23 , —PR 24 R 25 , —S(O) 2 R 26 , —S(O)R 27 , —SR 28 , or —OR 29 ;

R 20 and R 21 form, together with the nitrogen atom, a cyclic radical having 3 to 10 ring atoms, which is optionally substituted by one or more substituents selected from alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, and a group with donor or acceptor action, and/or optionally fused to one or more further cyclic radicals having 3 to 10 ring atoms, where the fused radicals are optionally substituted by one or more substituents selected from alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl and a group with donor or acceptor action; and

R 15 , R 16 , R 17 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , and R 29 are each independently aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl,

or

two units of formula (V) are linked via a linear or branched, saturated or unsaturated bridge, which is optionally interrupted by at least one hetero atom, via a bond, or via O.

9. The organic light-emitting diode of claim 8 , which comprises an emission layer comprising the metal-carbene complex, at least one matrix material of the formula (V), and at least one further hole-transporting matrix material.

10. A device selected from the group consisting of stationary visual display units, mobile visual display units, and illumination means, comprising an organic light-emitting diode of claim 8 .

11. An organic light-emitting diode comprising a metal-carbene complex of claim 1 , and at least one compound of the formula (II):

wherein:

X is NR, S, O, or PR, where wherein R is aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl each having a total of 1 to 30 carbon atoms and/or heteroatoms;

B is —NR 20 R 21 , —P(O)R 22 R 23 , —PR 24 R 25 , —S(O) 2 R 26 , —S(O)R 27 , —SR 28 , or —OR 29 ;

R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 and R 29 are each independently aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl each having a total of 1 to 40 carbon atoms and/or heteroatoms;

R 15 , R 16 , and R 17 are each independently aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl each having a total of 1 to 20 carbon atoms and/or heteroatoms, wherein at least one of the R 15 , R 16 , and R 17 radicals is aryl or heteroaryl;

R 18 and R 19 are each independently alkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl each having a total of 1 to 20 carbon atoms and/or heteroatoms and/or a B group and/or a group with donor or acceptor action; and

o and p are each independently 0, 1, 2, or 3;

R 20 and R 21 form, together with the nitrogen atom, a cyclic radical having 3 to 10 ring atoms, which is optionally substituted by one or more substituents selected from alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, and a group with donor or acceptor action, and/or may be fused to one or more further cyclic radicals having 3 to 10 ring atoms, wherein the fused radicals may be unsubstituted or substituted by one or more substituents selected from alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, and a group with donor or acceptor action.

12. An organic light-emitting diode comprising a metal-carbene complex of claim 1 , and at least one compound of the formula (VI):

wherein:

X′ is NR 37′ , S, O, PR 37′ , SO 2 or SO;

R 37′ is substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 6 -C 30 -aryl, or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms;

R 38′ , R 39′ , R 40′ , R 41′ , R 42′ , and R 43′ are each independently substituted or unsubstituted C 1 -C 20 -alkyl, substituted or unsubstituted C 6 -C 30 -aryl, or a structure of formula (c):

R a′ and R b′ are each independently substituted or unsubstituted substituted or unsubstituted C 6 -C 30 -aryl, or substituted or unsubstituted heteroaryl having from 5 to 30 ring atoms or a substituent with donor or acceptor action selected from the group consisting of: C 1 -C 20 -alkoxy, C 6 -C 30 -aryloxy, C 1 -C 20 -alkylthio, C 6 -C 30 -arylthio, SiR 34′ R 35′ R 36′ , halogen radicals, halogenated C 1 -C 20 -alkyl radicals, carbonyl (—CO(R 34′ )), carbonylthio (—C═O(SR 34′ )), carbonyloxy (—C═O(OR 34′ )), oxycarbonyl (—OC═O(R 34′ )), thiocarbonyl (—SC═O(R 34′ )), amino (—NR 34′ R 35′ ), OH, pseudohalogen radicals, amido (—C═O(NR 34′ )), —NR 34′ C═O(R 35′ ), phosphonate (—P(O)(OR 34′ ) 2 , phosphate (—OP(O)(OR 34′ ) 2 ), phosphine (—PR 34′ R 35′ ), phosphine oxide (—P(O)R 34′ 2 ), sulfate (—OS(O) 2 OR 34′ ), sulfoxide (S(O)R 34′ ), sulfonate (—S(O) 2 OR 34′ ), sulfonyl (—S(O) 2 R 34′ ), sulfonamide (—S(O) 2 NR 34′ R 35′ ), NO 2 , boronic esters (—OB(OR 34′ ) 2 ), imino (—C═NR 34′ R 35′ )), borane radicals, stannane radicals, hydrazine radicals, hydrazone radicals, oxime radicals, nitroso groups, diazo groups, vinyl groups, sulfoximines, alanes, germanes, boroximes, and borazines;

R 34′ , R 35′ , R 36′ are each independently substituted or unsubstituted C 1 -C 20 -alkyl, or substituted or unsubstituted C 6 -C 30 -aryl; and

q′ and r′ are each independently 0, 1, 2, or 3; wherein, in the case when q′ or r′ is 0, all substitutable positions of the aryl radical are substituted by hydrogen,

wherein the radicals and indices in the group of the formula (c) X′″, R 41′″ , R 42′″ , R 43′″ , R a′″ , R b′″ , q′″, and r′″ are each independently as defined for the radicals and indices of the compounds of the general formula (VI) X′, R 41′ , R 43′ , R a′ , R b′ , q′, and r′.

13. The organic light-emitting diode of claim 12 , which comprises an emission layer comprising the metal-carbene complex, at least one matrix material of the formula (VI), and at least one further hole-transporting matrix material.

14. An organic light-emitting diode comprising a metal-carbene complex of claim 1 .

15. The organic light-emitting diode of claim 14 , wherein the metal-carbene complex is present as an emitter, matrix material, charge transport material, and/or charge blocker.