Manganese (II) complex, preparation method thereof, and use thereof in organic light emitting diodes

Abstract

The invention relates to a manganese (II) complex, its preparation method and use. The structure of the complex is (R1R2R3R4A)2[MnX4], wherein R1, R2, R3 and R4 are identical or different, independently selected from alkyl, aryl, or heteroaryl; said alkyl, aryl, or heteroaryl can be optionally substituted with a substituent, and the substituent is preferably alkyl, aryl or heteroaryl; A is N, P, or As; X is optionally F, Cl, Br, or I. The present invention also relates to an organic light emitting diode, its preparation method and use, wherein the manganese (II) complex of the invention is used as a dopant in the light-emitting layer. The prepared organic light emitting diode exhibits high electrical-to-optical conversion efficiency which can be used for flat-panel displays and illuminations.

Claims

1. A manganese (II) complex of formula (I): ##STR00003## wherein R.sub.1 and R.sub.2 are identical and are 9-phenylcarbazyl, R.sub.3 and R.sub.4 are identical and are phenyl, A is P, and all four Xs are Br.

2. A method for preparing the manganese (II) complex according to claim 1, comprising the following steps: mixing MnX.sub.2 and (R.sub.1R.sub.2R.sub.3R.sub.4A)X in a solvent to obtain the manganese (II) complex, wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, A and X are defined according to claim 1.

3. An organic light emitting diode, comprising a light-emitting layer that comprises a manganese (II) complex having a formula of (R.sub.1R.sub.2R.sub.3R.sub.4A).sub.2[MnX.sub.4], wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are identical or different, and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently aryl or heteroaryl, which are unsubstituted or substituted with an alkyl group, an aryl group, or a heteroaryl group; A is N, P, or As; X is optionally F, Cl, Br, or I; and wherein alkyl is a linear or branched alkyl having 1 to 10 carbon atoms; the aryl is a monocyclic or polycyclic aromatic group having 6 to 20 carbon atoms; the heteroaryl is a monocyclic or polycyclic heteroaromatic group having 1 to 20 carbon atoms containing at least one heteroatoms selected from N, S or O. ##STR00004##

4. The organic light emitting diode according to claim 3, further comprising an anode layer, a hole injection layer/hole transport layer, an electron transport layer, an electron injection layer, and a cathode layer.

5. The organic light emitting diode according to claim 4, wherein the anode layer is indium tin oxide; the hole injection layer and the hole transport layer are PEDOT:PSS (PEDOT:PSS=poly(3,4-ethyleneoxythiophene)-poly(styrene sulfonate)); the light-emitting layer further comprises a substance having a hole-transport property selected from TCTA (tris(4-(9H-carbazol-9-yl)phenyl)amine), mCP (1,3-bis(9-carbazolyl)benzene), CBP (4,4′-bis(9H-carbazol-9-yl)-1,1′-biphenyl), 2,6-DCZPPY (2,6-bis (3-(9H-carbazol-9-yl)phenyl)pyridine), and mixtures thereof; the electron transport layer comprises TPBi (1,3,5-tris(1-phenyl-1H-benzo[d]imidazole-2-yl)phenyl), BmPyPB (3,3″, 5,5″-tetra(pyridin-3-yl)-1,1′:3′,1″-terphenyl), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), or OXD-7 (2,2′-(1,3-phenylene) bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole]; the electron injection layer is LiF; and the cathode layer is Al.

6. A method for preparing the organic light emitting diode according to claim 3, comprising: 1) fabricating a hole injection layer and a hole transport layer of the organic light emitting diode on an anode layer through solution process; 2) fabricating the light-emitting layer comprising the manganese (II) complex through solution process; and 3) fabricating an electron transport layer, an electron injection layer, and a cathode layer in sequence through vacuum thermal evaporation deposition process.

7. A display panel comprising a plurality of the organic light emitting diode according to claim 3.

8. A illumination device, comprising a plurality of the organic light emitting diode according to claim 3.

9. The organic light emitting diodes according to claim 3, wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently selected from aryl, heteroaryl, and arylheteroaryl.

10. The organic light emitting diodes according to claim 9, wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected from phenyl, carbazyl, and phenylcarbazyl.

11. The organic light emitting diodes according to claim 3, wherein A is N or P.

12. The organic light emitting diodes according to claim 3, wherein the manganese (II) complex is selected from compound 1, compound 2, compound 3, or compound 4, ##STR00005## wherein, in compound 1, all four Xs are Cl; wherein, in compound 2, all four Xs are Br; and wherein, in compound 3, all four Xs are I.

13. The organic light emitting diode according to claim 6, wherein, in the light-emitting layer, a weight percentage of the manganese (II) complex is 5-50%.

Description

DESCRIPTION OF THE DRAWING

(1) FIG. 1 is the schematic representation of the device and the chemical structures of organic materials.

SPECIFIC EMBODIMENTS

(2) In order to better explain the objects, technical solutions and technical effects, the present invention will be further illustrated with reference to the schemes and specific examples. However, those skilled in the art can readily understand that the following embodiments are not intended to limit the scope of the invention. Any improvement and modification based on the present invention are within the scope of the present invention.

Example 1: Preparation of (Ph.SUB.4.P).SUB.2.[MnCl.SUB.4.] (1) Complex

(3) To a solution of anhydrous MnCl.sub.2 (47.3 mg, 0.1 mmol) in 10 mL of methanol was added a solution of Ph.sub.4PCl (50.6 mg, 0.2 mmol) in 10 mL of methanol. After being stirred for 4 hours, the reaction solution was dried in vacuum. The obtained solid was dissolved in 5 mL of dichloromethane, and filtered to give a transparent filtrate. At room temperature, recrystallization by slow diffusion of petroleum ether into a dichloromethane solution afforded pale green crystals. Yield: 92%. Elemental analysis (C.sub.48H.sub.40C.sub.14P.sub.2Mn), calculated data: C, 65.85; H, 4.60. Found: C, 65.56; H, 4.57. IR (KBr, cm.sup.−1): 3843, 3741, 3633, 3517, 3057, 1625, 1586, 1484, 1437, 1315, 1111, 993, 766, 727, 687, 527.

Example 2: Preparation of (Ph.SUB.4.P).SUB.2.[MnBr.SUB.4.] (2) Complex

(4) The preparation method was basically the same as that described in Example 1, except that anhydrous MnCl.sub.2 was replaced by anhydrous MnBr.sub.2, and Ph.sub.4PCl was replaced by Ph.sub.4PBr. Yield: 95%. Elemental analysis (C.sub.48H.sub.40Br.sub.4P.sub.2Mn), calculated data: C, 54.73; H, 3.83. Found: C, 54.25; H, 3.78. IR (KBr, cm.sup.−1): 3850, 3736, 3473, 3051, 1621, 1587, 1483, 1107, 996, 758, 724, 692, 528.

Example 3: Preparation of (Ph.SUB.4.P).SUB.2.[MnI.SUB.4.] (3) Complex

(5) The preparation method was basically the same as that described in Example 1, except that anhydrous MnCl.sub.2 was replaced by anhydrous MnI.sub.2, and Ph.sub.4PCl was replaced by Ph.sub.4PI. Yield: 75%. Elemental analysis (C.sub.48H.sub.40I.sub.4P.sub.2Mn), calculated data: C, 46.40; H, 3.25. Found: C, 46.90; H, 3.28. IR (KBr, cm.sup.−1): 3847, 3454, 3057, 1625, 1585, 1485, 1437, 1385, 1313, 1110, 997, 759, 724, 689, 526, 448.

Example 4: Preparation of [Ph.SUB.2.P(Carbazol-9-Yl).SUB.2.].SUB.2 .[MnBr.SUB.4.] (4) Complex

(6) The preparation method was basically the same as that described in Example 2, except that anhydrous Ph.sub.2PBr was replaced by synthesized Ph.sub.2P(carbazol-9-yl).sub.2Br. Yield: 78%. Elemental analysis (C.sub.72H.sub.54Br.sub.4N.sub.2P.sub.2Mn), calculated data: C, 62.50; H, 3.93; N, 2.02. Found: C, 65.26; H, 3.90; N, 2.11. IR (KBr, cm.sup.−1): 3860, 3754, 3470, 3055, 1628, 1581, 1484, 1422, 1391, 1112, 998, 757, 729, 671, 526.

Example 5: Preparation of [(n-Bu).SUB.4.N].SUB.2.[MnBr.SUB.4.] (5) Complex

(7) The preparation method was basically the same as that described in Example 2, except that anhydrous Ph.sub.2PBr was replaced by (n-Bu).sub.4NBr. Yield: 87%. Elemental analysis (C.sub.32H.sub.72Br.sub.4N.sub.2Mn), calculated data: C, 44.72; H, 8.44; N, 3.26. Found: C, 44.56; H, 8.26; N, 3.38. IR (KBr, cm.sup.−1): 3465, 3423, 2958, 2868, 1486, 1387, 1155, 1033, 873, 747.

Example 6: Photoluminescence Performance Measurement

(8) The excitation spectra, the emission spectra, the luminescence lifetimes and the luminescence quantum yields of the complex 1-5 crystals prepared in Examples 1-5 and the thin films of 40% TCTA: 40% 2,6-DCZPPY: 20% of the manganese (II) complexes of Examples 1-5 (by weight) were measured on Edinburgh FLS920 fluorescence spectrometer, respectively. The luminescence quantum yields of the crystal samples were determined by using a 142 mm-diameter integrating sphere. The luminescence quantum yields of the thin films of 40% TCTA: 40% 2,6-DCZPPY: 20% of the manganese (II) complexes of Examples 1-5 (by weight) (the thin films are prepared by spin-coating dichloromethane solutions of the above materials) are determined on the 142 mm-diameter integrating sphere.

(9) The complexes 1-5 in Examples 1-5 exhibit strong phosphorescence emissions in crystals and thin films. The emission wavelengths, the emission lifetimes and the quantum yields are listed in Table 1.

(10) TABLE-US-00001 TABLE 1 Photoluminescence emission wavelengths, emission lifetimes and quantum yields of the complex 1-5 of the present invention Crystal Thin film Complex λ.sub.em [nm] τ.sub.em [μs] Φ.sub.em [%] λ.sub.em [nm] τ.sub.em [μs] Φ.sub.em [%] 1 517 1339 75.7 517 1365 24.4 2 515 357 98.5 521 317 71.2 3 529 158 29.3 521 305 31.7 4 520 127.9 8.6 519 172.9 45.2 5 518 352.4 71.3 518 415.5 31.5

Example 7: Fabrication of Organic Light Emitting Diodes and Electroluminescence Performance Measurement

(11) The organic light emitting diodes were fabricated by using 20% by weight of the phosphorescent complexes 1-5 prepared in Examples 1-5 as luminescent materials doped into the blended host materials of TCTA (40%): 2,6-DCZPPY (40%) in the light-emitting layers, respectively. The device structures were preferably ITO/PEDOT:PSS (50 nm)/40% TCTA: 40% 2,6-DCZPPY: 20% wt of the manganese (II) complexes 1-5 (50 nm) in Examples 1-5/TPBi (50 nm)/LiF (1 nm)/Al (100 nm).

(12) Firstly, the ITO substrates were cleaned by using deionized water, acetone and isopropanol, respectively, followed by UV-Ozone treatment for 15 min. The filtered aqueous solution of PEDOT:PSS was spin coated onto the ITO substrates at 3000 rpm, dried at 140° C. for 20 min to afford 50 nm thick hole injection/hole transport layers. Then the filtered solution of 40% TCTA: 40% 2,6-DCZPPY: 20% wt of the manganese (II) complexes 1-5 in Examples 1-5 (percentage by weight) in dichloromethane was spin coated onto the PEDOT:PSS thin films to form 50 nm thick light emitting layers. After that, the ITO substrates were loaded into a vacuum deposition chamber with a pressure of less than 4×10.sup.−4 Pa, and were subsequently thermally deposited with 50 nm thick TPBi electron transport layers, 1 nm thick LiF electron injection layers and 100 nm thick Al cathodes.

(13) The LED device performance was determined at room temperature in the dry ambient air. The parameters of the electroluminescence performance of the manganese (II) complexes 1-5 prepared in Examples 1-5, including electroluminescence emission wavelength (λ.sub.EL), turn-on voltage (V.sub.on), maximum luminance (L.sub.max), maximum current efficiency (CE.sub.max), maximum power efficiency (PE.sub.max), and maximum external quantum efficiency (EQE.sub.max), are listed in Table 2.

(14) TABLE-US-00002 TABLE 2 Electroluminescence performance data of the phosphorescent manganese (II) complex 1-5 of the present invention λ.sub.EL V.sub.on.sup.a) L.sub.max.sup.b) CE.sub.max.sup.c) PE.sub.max.sup.d) EQE.sub.max.sup.e) Complex [nm] [V] [cd/m.sup.2] [cd/A] [lm/W] [%] 1 527 5.9 958 8.2 3.2 2.2 2 521 4.8 2340 32.1 16.2 9.6 3 531 5.5 1229 17.6 8.1 4.8 4 520 6.4 2083 23.7 9.4 6.8 5 528 5.5 1089 17.3 8.1 4.6 .sup.a)turn-on voltage (V.sub.on) at luminance of 1 cd/m.sup.2, .sup.b)maximum luminance, .sup.c)maximum current efficiency, .sup.d)maximum power efficiency, e) maximum external quantum efficiency.