Organic electroluminescent materials and devices

1. An organic light emitting device (OLED) having an emission spectrum, the OLED comprising:

an anode;

a cathode; and

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

a first host material having a highest occupied molecular orbital (HOMO) energy and a lowest unoccupied molecular orbital (LUMO) energy; and

an emitter material having a HOMO energy and a LUMO energy;

wherein,

all materials in the organic emissive layer are mixed together;

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

High HOMO energy is the highest HOMO energy among all materials in the organic emissive layer;

Low LUMO energy is the lowest LUMO energy among all materials in the organic emissive layer;

a≤E T −ΔE≤b, wherein E T is triplet energy T 1 of the emitter material, which is the lowest T 1 energy among all materials in the organic emissive layer, ΔE is the energy gap between the High HOMO energy and the Low LUMO energy, a is 0.00 up to 0.15 eV, and b is 0.05 up to 0.45 eV; and

wherein root mean squared function (RMSD) value for the emission spectrum of the OLED and an emission spectrum of a reference OLED, whose organic emissive layer consists of the emitter material and an inert host, is not greater than 0.05,

wherein RMSD value is a single value that represents the average difference between the emission spectrum of the OLED and the emission spectrum of the reference OLED at all wavelengths obtained by the following equation:

RMSD=√{square root over (1/ nΣ n 1 ( I 1 (λ)− I 2 (λ)) 2 )},

wherein n is the number of points on the two emission spectrums being compared, and I 1 and I 2 are the normalized intensity spectrums as a function of wavelength, λ.

2. The OLED of claim 1 , wherein the emitter material is a phosphorescent metal complex.

3. The OLED of claim 1 , wherein the emitter material is a delayed fluorescent emitter.

4. The OLED of claim 1 , wherein E T is at least 2.60 eV.

5. The OLED of claim 1 , wherein the High HOMO energy is the HOMO energy of the emitter material, and the Low LUMO energy is the LUMO energy of the first host.

6. The OLED of claim 1 , wherein the High HOMO energy is the HOMO energy of the first host, and the Low LUMO energy is the LUMO energy of the emitter material.

7. The OLED of claim 1 , wherein the OLED further comprises a second host, wherein the High HOMO energy is the HOMO energy of the first host, and the Low LUMO energy is the LUMO energy of the second host.

8. The OLED of claim 1 , wherein the OLED further comprises a second host, wherein the High HOMO energy is the HOMO energy of the second host, and the Low LUMO energy is the LUMO energy of the first 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 moiety selected from the group consisting of triphenylene, carbazole, indolocarbazole, benzothiophene, benzofuran, dibenzothiophene, dibenzofuran, pyridine, pyridazine, pyrimidine, pyrazine, triazine, imidazole, boryl, 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene, and aza-variants thereof.

11. The OLED of claim 1 , wherein the emitter material is a phosphorescent blue emitter.

12. The OLED of claim 1 , wherein the emitter material 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;

x is 1, 2, or 3;

y is 0, 1, or 2;

z is 0, 1, or 2;

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

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

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

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;

R a , R b , R c , and R d are each independently a hydrogen or a substituent selected from the group consisting of 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, boryl, and combinations thereof; and

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.

13. The OLED of claim 12 , wherein at least one of R a , R b , R c , and R d comprises a chemical group containing at least three 6-membered aromatic rings that are not fused next to each other.

14. The OLED of claim 12 , wherein the emitter material has the formula selected from the group consiting of Ir(L 1 )(L 2 )(L 3 ), Ir(L 1 ) 2 (L 2 ), and Ir(L 1 ) 3 ;

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

15. The OLED of claim 12 , wherein the emitter material has the formula of M(L 1 ) 2 or M(L 1 )(L 2 );

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

16. The OLED of claim 12 , wherein L 1 is selected from the group consisting of:

17. The OLED of claim 15 , wherein the emitter material is selected from the group consisting of:

wherein,

each R A to R F may represent from mono substitution to the possible maximum number of substitution, or no substitution;

R A to R F are each independently a hydrogen or a substitution selected from the group consisting of 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, boryl, and combinations thereof; and

any two R A to R F are optionally fused or joined to form a ring or form a multidentate ligand.

18. The OLED of claim 17 , wherein at least one of R A to R F comprises a chemical group containing at least three 6-membered aromatic rings that are not fused next to each other.

19. A consumer product comprising an organic light-emitting device (OLED) having an emission spectrum, the OLED comprising:

an anode;

a cathode; and

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

a first host material having a highest occupied molecular orbital (HOMO) energy and a lowest unoccupied molecular orbital (LUMO) energy; and

an emitter material having a HOMO energy and a LUMO energy;

wherein,

all materials in the organic emissive layer are mixed together;

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

High HOMO energy is the highest HOMO energy among all materials in the organic emissive layer;

Low LUMO energy is the lowest LUMO energy among all materials in the organic emissive layer;

a≤E T −ΔE≤b, wherein E T is triplet energy T 1 of the emitter material, which is the lowest T 1 energy among all materials in the organic emissive layer, ΔE is the energy gap between the High HOMO energy and the Low LUMO energy, a is 0.00 upto 0.15 eV, and b is 0.05 upto 0.45 eV; and

wherein root mean squared function (RMSD) value representing the difference between the emission spectrum of the OLED and an emission spectrum of a reference OLED, whose organic emissive layer consists of the emitter material and an inert host, is not greater than 0.05,

wherein the RMSD value is a single value that represents the average difference between the two emission spectrums at all wavelengths obtained by the following equation:

RMSD=√{square root over (1/ nΣ n 1 ( I 1 (λ)− I 2 (λ)) 2 )},

wherein n is the number of points on the two emission spectrums being compared, and I 1 and I 2 are the normalized intensity spectrums as a function of wavelength, λ.

20. The consumer product of claim 19 , wherein the consumer product is selected from the group consisting of a flat panel 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 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.