Organic electroluminescent materials and devices

1. A compound having a metal planar tetradentate coordination configuration with a structure of Formula I:

wherein the compound is mononuclear and the metal M is Pt or Pd;

wherein the four coordinating atoms are Z 1 , Z 2 , Z 3 , and Z 4 ;

wherein each one of Z 1 , Z 2 , Z 3 , and Z 4 is independently selected from the group consisting of N and C;

wherein the compound comprises a substituent R;

wherein M, Z 1 , Z 2 , Z 3 , and Z 4 are used to define a first plane that passes through the metal M and is positioned to have a minimum sum of shortest distances with Z 1 , Z 2 , Z 3 , and Z 4 ;

wherein at least one non-hydrogen atom in R falls within a distal circle of a cylinder extending perpendicular to the first plane as shown below;

wherein a base circle of the cylinder is in the first plane and has a center at metal M;

wherein the base circle and the distal circle have a radius r that is a largest distance selected from M-Z 1 , M-Z 2 , M-Z 3 , and M-Z 4 ;

wherein the distal circle of the cylinder is a height h from the base circle;

wherein the height h is a distance ranging from 3.3 Å to 4.8 Å;

wherein rings A, B, C, and D each independently represent a 5-membered or 6-membered carbocyclic or heterocyclic ring;

wherein R A , R B , R C , and R D each independently represent mono to a maximum possible number of substitution, or no substitution;

wherein L 1 and L 3 are each independently selected from the group consisting of a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO 2 , CRR′, SiRR′, GeRR′, alkyl, and combinations thereof,

wherein n 1 and n 2 each independently is 0 or 1;

wherein at least one of n 1 and n 2 is 1;

wherein, when present, each of L 2 and L 4 is independently selected from the group consisting of a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO2, CR′R″, SiR′R″, GeR′R″, alkyl, and combinations thereof;

wherein each R A , R B , R C , R D , R′, and R″ is independently selected from the group consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

wherein any adjacent R A , R B , R C , R D , R′, and R″ are optionally joined to form an aromatic ring;

wherein each of Q 1 , Q 2 , Q 3 and Q 4 is independently selected from the group consisting of a direct bond and oxygen;

wherein, when any of the Q 1 , Q 2 , Q 3 and Q 4 represent an oxygen atom, the corresponding Z 1 , Z 2 , Z 3 , or Z 4 is a carbon atom;

wherein at least one of R A , R B , R C , and R D is -L-R;

wherein R is selected from the group consisting of cycloalkyl, aryl, heteroaryl, substituted variants thereof, and combination thereof; and

wherein L is selected from the group consisting of

with the proviso that (1) -L-R is not a combination of L=

 and R=

 and (2) if L is

 then R comprises a moiety selected from the group consisting of cycloalkyl, a polycyclic aromatic system, and at least three aromatic rings.

2. The compound of claim 1 , wherein at least two non-hydrogen atoms in R falls within the distal circle.

3. The compound of claim 1 , wherein at least a portion of an aromatic ring in R falls within the distal circle.

4. The compound of claim 1 , wherein each of Q 1 , Q 2 , Q 3 and Q 4 is a direct bond.

5. The compound of claim 1 , wherein one of Q 1 , Q 2 , Q 3 and Q 4 is oxygen and the other three of Q 1 , Q 2 , Q 3 and Q 4 are direct bonds.

6. The compound of claim 4 , wherein two of Z 1 , Z 2 , Z 3 and Z 4 are carbon atoms and the other two of Z 1 , Z 2 , Z 3 and Z 4 are nitrogen atoms.

7. The compound of claim 4 , wherein the compound is in cis configuration.

8. The compound of claim 1 , wherein rings A, B, C and D are each independently selected from the group consisting of phenyl, pyridine, imidazole, pyrrole, pyrazole, and imidazole derived carbene.

9. The compound of claim 1 , wherein the compound is selected from the group consisting of:

10. The compound of claim 1 , wherein the compound is selected from the group consisting of:

11. The compound of claim 1 , wherein L is independently selected from the group consisting of:

12. The compound of claim 1 , wherein R is selected from groups consisting of:

13. 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 of claim 1 .

14. The OLED of claim 13 , wherein the organic layer is an emissive layer and the compound is an emissive dopant or a non-emissive dopant.

15. The OLED of claim 13 , wherein the organic layer further comprises a host, wherein the host comprises at least one selected from the group consisting of metal complex, triphenylene, carbazole, dibenzothiophene, dibenzofuran, dibenzoselenophene, azatriphenylene, azacarbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

16. The OLED of claim 13 , wherein the organic layer further comprises a host, wherein the host is selected from the group consisting of:

and combinations thereof.

17. A consumer product comprising an organic light-emitting device comprising:

an anode;

a cathode; and

an organic layer, disposed between the anode and the cathode, comprising a compound of claim 1 .

18. The consumer product of claim 17 , wherein the consumer product is one 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 wall comprising multiple displays tiled together, a theater or stadium screen, or a sign.

19. The compound of claim 1 , wherein -L-R is not a combination of L=

and R=

20. A compound selected from group consisting of: