Organic electroluminescent materials and devices

1. A first device comprising a first organic light emitting device, comprising:

an anode;

a cathode; and

an emissive layer, disposed between the anode and the cathode;

wherein the emissive layer comprises a host material doped with a first emitting compound, wherein the first emitting compound has a structure of formula I:

wherein Z 1 , Z 2 , Z 3 , Z 4 and Z 5 are each independently selected from group consisting of CR 9 and N;

wherein any adjacent R 9 are optionally joined to form a fused ring;

wherein at least one of Z 1 , Z 2 , Z 3 , Z 4 and Z 5 is N;

wherein L 1 is selected from the group consisting of:

and combinations thereof;

wherein X 1 is O, S, or CRR';

wherein R, R′ are optionally joined to form a ring;

wherein n 1 is an integer from 1 to 20;

wherein L 1 can be further substituted by a substituent selected from the group consisting of alkyl, aryl, and heteroaryl;

wherein at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 comprises an electron donor group;

wherein any two adjacent R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 are not joined to form a ring;

wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 do not contain an electron acceptor group;

wherein R 9 does not contain an electron donor group;

wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combinations thereof; and

wherein R 9 , R, and R′ are independently selected from the group consisting of hydrogen, deuterium, alkyl, cycloalkyl, heteroalkyl, arylalkyl, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, and combinations thereof.

2. The first device of claim 1 , wherein the electron donor group comprises at least one chemical group selected from the group consisting of amino, indole, carbazole, benzothiohpene, benzofuran, benzoselenophene, dibenzothiophene, dibenzofuran, dibenzoselenophene, and combinations thereof.

3. The first device of claim 2 , wherein the electron donor group comprises at least one chemical group selected from the group consisting of:

wherein X and Y are selected from the group consisting of O, S, NR 14 ;

wherein m is an integer from 1 to 20;

wherein n 2 is an integer from 1 to 20;

wherein R 11 , R 12 , R 13 and R 14 are selected from the group consisting of aryl and heteroaryl.

4. The first device of claim 1 , wherein the donor group is selected from the group consisting of:

5. The first device of claim 1 , wherein the first emitting compound having the formula:

and

wherein R 91 and R 92 are independently selected from aryl or heteroaryl, and can be further substituted.

6. The first device of claim 1 , wherein the first emitting compound has a formula selected from the group consisting of:

7. The first device of claim 1 , wherein the first emitting compound has a formula selected from the group consisting of:

8. The first device of claim 1 , wherein the first device emits a luminescent radiation at room temperature when a voltage is applied across the organic light emitting device;

wherein the luminescent radiation comprises a delayed fluorescence process.

9. The first device of claim 1 , wherein the emissive layer further comprises a first phosphorescent emitting material.

10. The first device of claim 9 , wherein the emissive layer further comprises a second phosphorescent emitting material.

11. The first device of claim 9 , wherein the first device emits a white light at room temperature when a voltage is applied across the organic light emitting device.

12. The first device of claim 11 , wherein the first emitting compound emits a blue light with a peak wavelength of about 400 nm to about 500 nm.

13. The first device of claim 11 , wherein the emitting compound emits a yellow light with a peak wavelength of about 530 nm to about 580 nm.

14. The first device of claim 1 , wherein the first device comprises a second organic light emitting device;

wherein the second organic light emitting device is stacked on the first organic light emitting device.

15. The first device of claim 1 , wherein the first device is a consumer product.

16. The first device of claim 1 , wherein the first device is an organic light-emitting device.

17. The first device of claim 1 , wherein the first device is a lighting panel.