Organic electroluminescent materials and devices

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

an anode;

a cathode; and

an organic emissive layer disposed between the anode and the cathode, the organic emissive layer comprising:

a first host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the first host is an electron transporting host; and

an emitter having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the emitter is a blue emitter;

wherein the emitter is selected from the group consisting of a phosphorescent metal complex, and a delayed fluorescent emitter;

wherein E H1T , the T 1 triplet energy of the first host, is higher than E ET , the T 1 triplet energy of the emitter;

wherein E ET is at least 2.50 eV;

wherein the LUMO energy of the first host is higher than the HOMO energy of the emitter;

wherein the absolute value of the difference between the HOMO energy of the emitter and the LUMO energy of the first host is ΔE1;

wherein a≤ΔE1−E ET ≤b; and

wherein a≥0.05 eV, and b≤0.60 eV.

2. The OLED of claim 1 , wherein the absolute value of the difference between the highest HOMO energy and the lowest LUMO energy among all components in the emissive layer is larger than E ET by at least a.

3. The OLED of claim 1 , wherein the OLED further comprises a second host;

wherein E H2T , the T 1 triplet energy of the second host, is higher than E ET .

4. The OLED of claim 3 , wherein the HOMO energy of the second host is lower than the HOMO energy of the first host, the LUMO energy of the second host is higher than the LUMO energy of the first host.

5. The OLED of claim 3 , wherein the HOMO energy of the second host is higher than the HOMO energy of the first host, the LUMO energy of the second host is higher than the LUMO energy of the first host.

6. The OLED of claim 3 , wherein the difference of HOMO energy between the first and the second host is from 0.1 to 0.6 eV.

7. The OLED of claim 3 , wherein the difference of HOMO energy between the emitter and the second host is from 0.05 to 0.8 eV.

8. The OLED of claim 3 , wherein the second host is a hole transporting host.

9. The OLED of claim 1 , wherein the device has an operation voltage less than 6.0 V at 10 mA/cm 2 .

10. The OLED of claim 1 , wherein the first host comprises at least one chemical group selected from the group consisting of pyridine, pyrimidine, pyrazine, triazine, imidazole, aza-triphenylene, aza-carbazole, aza-dibenzothiophene, aza-dibenzofuran, and aza-dibenzoselenophene.

11. The OLED of claim 1 , wherein the emitter has the formula of M(L 1 ) X (L 2 ) y (L 3 ) z ;

wherein L 1 , L 2 and L 3 can be the same or different;

wherein x is 1, 2, or 3;

wherein y is 0, 1, or 2;

wherein z is 0, 1, or 2;

wherein x+y+z is the oxidation state of the metal M;

wherein L 1 , L 2 and L 3 are each independently selected from the group consisting of:

wherein each X 1 to X 17 are independently selected from the group consisting of carbon and nitrogen;

wherein X is selected from the group consisting of BR′, NR′, PR′, O, S, Se, C═O, S═O, SO 2 , CR′R″, SiR′R″, GeR′R″;

wherein R′ and R″ are optionally fused or joined to form a ring;

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

wherein R′, R″, R a , R b , R c , and R d are each independently selected from the group consisting of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclic amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

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

12. The OLED of claim 11 , wherein the compound has the formula selected from the group consisting of Ir(L 1 )(L 2 )(L 3 ), Ir(L 1 ) 2 (L 2 ), and Ir(L 1 ) 3 ;

wherein L 1 , L 2 and L 3 are different and each independently selected from the group consisting of:

13. The OLED of claim 11 , wherein the compound has the formula of Pt(L 1 ) 2 or Pt(L 1 )(L 2 ).

14. The OLED of claim 11 , wherein the compound has the formula of M(L 1 ) 2 or M(L 1 )(L 2 );

wherein M is Ir, Rh, Re, Ru, or Os, L 1 and L 2 are each a different tridentate ligand.

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

16. A consumer product comprising an OLED according to claim 1 .

17. The consumer product of claim 16 , 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 mobile phone, a tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or a stadium screen, and a sign.

18. An organic light emitting device (OLED), comprising:

an anode;

a cathode; and

an organic emissive layer disposed between the anode and the cathode comprising:

a first host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the first host is an electron transporting host;

a second host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy; and

an emitter having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the emitter is a blue emitter;

wherein the emitter is selected from the group consisting of a phosphorescent metal complex, and a delayed fluorescent emitter;

wherein E H1T , the T 1 triplet energy of the first host, is higher than E ET , the T 1 triplet energy of the emitter;

wherein E ET is at least 2.50 eV;

wherein the HOMO energy of the first host is higher than the HOMO energy of the second host;

wherein the absolute value of the difference between the HOMO energy of the emitter and the HOMO energy of the first host is ΔE2;

wherein ΔE2≤d;

wherein d is 1.2 eV;

wherein the absolute value of the difference between the LUMO energy of the emitter and the HOMO energy of the first host is ΔE3;

wherein a≤ΔE3−E ET ≤b; and

wherein a≥0.05 eV, and b≤0.60 eV.

19. An organic light emitting device (OLED), comprising:

an anode;

a cathode; and

an organic emissive layer disposed between the anode and the cathode, the organic emissive layer comprising:

a first host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the first host is an electron transporting host;

a second host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy;

a third host having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy; and

an emitter having a highest occupied molecular orbital (HOMO) energy, a lowest unoccupied molecular orbital (LUMO) energy, and a T 1 triplet energy, wherein the emitter is a blue emitter;

wherein the emitter is a phosphorescent metal complex having E ET , T 1 triplet energy, of at least 2.50 eV;

wherein the LUMO energy of the first host is higher than the HOMO energy of the emitter;

wherein the absolute value of the difference between the HOMO energy of the emitter and the LUMO energy of the first host is ΔE1;

wherein the HOMO energy of the second host is lower than the HOMO energy of the emitter;

wherein the absolute value of the difference between the HOMO energy of the emitter and the HOMO energy of the second host is ΔE4;

wherein a≤ΔE1−E ET ≤b; wherein a≥0.005 eV, and b≤0.60 eV; and

wherein ΔE4≤d, wherein d is 1.2 eV; and

wherein the HOMO energy of the third host is lower than the HOMO energy of the second host.