Organic electroluminescent materials and devices

1. An organic light emitting device (OLED) comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound having a formula selected from the group consisting of Formula I and Formula II:

wherein R is selected from the group consisting of:

wherein R 4 is selected from the group consisting of

wherein X is Se;

wherein R 1 , R 2 and R 3 each independently represents mono to maximum allowable substitutions, or no substitution;

wherein R 1 , R 2 and R 3 are each independently selected from the group consisting of hydrogen, deuterium, alkyl, alkenyl, alkyne, alkoxy, halogen, silyl, nitrile, nitro, aryl, heteroaryl and combinations thereof;

wherein any two adjacent substituents are optionally joined or fused into a ring;

wherein R 4 , R 1 , R 2 , and R 3 are each independently, optionally, further substituted with one or more substituents selected from the group consisting of hydrogen, deuterium, alkyl, alkenyl, alkyne, alkoxy, halogen, silyl, nitrile, nitro, aryl, heteroaryl, and combinations thereof; and

wherein any hydrogen in the compound is optionally replaced with deuterium.

2. The OLED of claim 1 , wherein the organic layer is an emissive layer and the compound of Formula I, or II is a host.

3. The OLED of claim 1 , wherein the organic layer further comprises a phosphorescent emissive dopant; wherein the emissive dopant is a transition metal complex having at least one ligand or part of the ligand if the ligand is more than bidentate selected from the group consisting of:

wherein each Y 1 to Y 13 are independently selected from the group consisting of carbon and nitrogen;

wherein Y′ is selected from the group consisting of BR e , NR e , PR e , O, S, Se, C═O, S═O, SO 2 , CR e R f RR, SiR e R f , and GeR e R f ;

wherein R e and R f are optionally fused or joined to form a ring;

wherein each R a , R b , R c , and R d may independently represent from mono substitution to the maximum possible number of substitution, or no substitution;

wherein each R a , R b , R c , R d , R e , and R f is independently selected from the group consisting of hydrogen, deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, and combinations thereof; and

wherein any two adjacent substituents of R a , R b , R c , and R d are optionally fused or joined to form a ring or form a multidentate ligand.

4. The OLED of claim 1 , wherein the organic layer is a blocking layer and the compound of Formula I, or II is a blocking material in the organic layer.

5. The OLED of claim 1 , wherein the organic layer is a transporting layer and the compound of Formula I, or II is a transporting material in the organic layer.

6. A consumer product comprising the OLED of claim 1 .

7. The consumer product of claim 6 , wherein the consumer product is selected from the group consisting of a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display that is less than 2 inches diagonal, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video walls comprising multiple displays tiled together, a theater or stadium screen, and a sign.

8. A compound having a formula selected from the group consisting of Formula I and Formula II:

wherein R is selected from the group consisting of:

wherein R 4 is selected from the group consisting of

wherein X is Se;

wherein R 1 , R 2 and R 3 each independently represents mono to maximum allowable substitutions, or no substitution;

wherein R 1 , R 2 and R 3 are each independently selected from the group consisting of hydrogen, deuterium, alkyl, alkenyl, alkyne, alkoxy, halogen, silyl, nitrile, nitro, aryl, heteroaryl and combinations thereof;

wherein any two adjacent substituents are optionally joined or fused into a ring;

wherein R 4 , R 1 , R 2 , and R 3 are each independently, optionally, further substituted with one or more substituents selected from the group consisting of hydrogen, deuterium, alkyl, alkenyl, alkyne, alkoxy, halogen, silyl, nitrile, nitro, aryl, heteroaryl, and combinations thereof; and

wherein any hydrogen in the compound is optionally replaced with deuterium.

9. The compound of claim 8 , wherein the first compound is Formula I.