OLED device employing alkali metal cluster compounds

1. An OLED device comprising a cathode, an anode, and having therebetween a layer containing a neutrally charged mixed cluster compound comprising first and second subunits with the first subunit comprising an alkali metal salt of a nitrogen containing heterocyclic ligand bearing an anionic hydroxy group and the second subunit comprising an organic alkali metal salt different than the first subunit, wherein the alkali metal cations of both subunits are the same.

2. The OLED device of claim 1 further comprising a light-emitting layer located between the cathode and anode and wherein the layer containing the cluster compound is located between the light-emitting layer and the cathode.

3. The OLED device of claim 1 wherein the alkali metal cations are lithium.

4. The OLED device of claim 1 wherein the first subunit of the cluster compound is according to formula (I):

wherein:

M represents an alkali metal cation; and

Z represents the atoms completing a nucleus having at least two fused aromatic rings.

5. The OLED device of claim 4 wherein the first subunit of the cluster compound is according to formula (II):

wherein:

M represents an alkali metal cation; and

R 1 -R 6 individually represent a hydrogen, or an alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups may be joined together to form an annulated saturated or aromatic ring system.

6. The OLED device of claim 1 wherein the first subunit is according to formula (III):

wherein:

M represents an alkali metal cation;

R 7 -R 10 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and A, may be joined together to form an annulated saturated or aromatic ring system; and

A represents the atoms necessary to complete a 5, 6, 7 or 8 member ring system.

7. The OLED device of claim 6 wherein first subunit is according to formula (IV):

wherein:

M represents an alkali metal cation; and

R 7 -R 14 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and R 14 , may be joined together to form an annulated saturated or aromatic ring system.

8. The OLED device of claim 7 wherein the first subunit is according to formula (V):

wherein:

M represents an alkali metal cation; and

R 7 -R 10 and R 15 -R 21 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and R 21 , may be joined together to form an annulated saturated or aromatic ring system.

9. The OLED device of claim 4 wherein the second subunit is formula (III):

wherein:

M represents an alkali metal cation;

R 7 -R 10 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and A, may be joined together to form an annulated saturated or aromatic ring system; and

A represents the atoms necessary to complete a 5, 6, 7 or 8 member ring system.

10. The OLED device of claim 1 wherein the organic alkali metal salt of the second subunit is either:

(i) an alkali metal salt of a nitrogen containing heterocyclic ligand bearing an anionic hydroxy group different than the first subunit; or

(ii) an alkali metal salt of a phenol or naphthol.

11. A neutrally charged mixed cluster compound comprising first and second subunits with the first subunit comprising an alkali metal salt of a nitrogen containing heterocyclic ligand bearing an anionic hydroxy group and the second subunit comprising an organic alkali metal salt different from the first subunit, wherein the alkali metal cations of both subunits are the same.

12. The cluster compound of claim 11 wherein the alkali metal cations are lithium.

13. The cluster compound of claim 11 wherein the organic alkali metal salt of the second subunit is an alkali metal salt of a nitrogen containing heterocyclic ligand bearing an anionic hydroxy group.

14. The cluster compound of claim 11 wherein the first subunit is according to formula (I):

wherein:

M represents an alkali metal cation; and

Z represents the atoms completing a nucleus having at least two fused aromatic rings.

15. The cluster compound of claim 14 wherein the first subunit is according to formula (II):

wherein:

M represents an alkali metal cation; and

R 1 -R 6 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups may be joined together to form an annulated saturated or aromatic ring system.

16. The cluster compound of claim 11 wherein the first subunit is according to formula (III):

wherein:

M represents an alkali metal cation; and

R 7 -R 10 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or R 7 and A, may be joined together to form an annulated saturated or aromatic ring system; and

A represents the atoms necessary to complete a 5, 6, 7 or 8 member ring system.

17. The cluster compound of claim 16 wherein the first subunit is according to formula (IV):

wherein:

M represents an alkali metal cation; and

R 7 -R 14 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and R 14 , may be joined together to form an annulated saturated or aromatic ring system.

18. The cluster compound of claim 17 wherein the first subunit is according to formula (V):

wherein:

M represents an alkali metal cation; and

R 7 -R 10 and R 15 -R 21 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and R 21 , may be joined together to form an annulated saturated or aromatic ring system.

19. The cluster compound of claim 14 wherein the second subunit is formula (III):

wherein:

M represents an alkali metal cation;

R 7 -R 10 individually represent a hydrogen, alkyl, alkenyl, alkynyl, alkyloxy, alkylthio, amino, aryl, aryloxy, arylthio, cyano or heterocyclic group, with the proviso that any two adjacent R groups, or specifically R 7 and A, may be joined together to form an annulated saturated or aromatic ring system; and

A represents the atoms necessary to complete a 5, 6, 7 or 8 member ring system.

20. The cluster compound of claim 11 wherein the second subunit is an alkali metal salt of a phenol or naphthol.

21. A method of preparing the mixed cluster compound of claim 11 wherein compounds corresponding to the individual subunits are heated together in a non-reactive organic solvent with a boiling point of at least 100° C.

22. A method of preparing the mixed cluster compound of claim 11 wherein compounds corresponding to the individual subunits are heated together in the solid state.

23. The method of claim 22 wherein compounds corresponding to the individual subunits are heated together in the solid state and the mixed cluster compound is isolated via sublimation.

24. The OLED device of claim 1 wherein the neutrally charged mixed cluster compound is prepared by sublimating a mixture of the first and second subunits.

25. The cluster compound of claim 11 wherein the neutrally charged mixed cluster compound is prepared by sublimating a mixture of the first and second subunits.