Fluorine-fluorine associates

Abstract

The present invention relates, inter alia, to compositions comprising, a compound which is able to emit and/or absorb light and a compound which is able either to absorb or emit light, where both compounds each include at least one fluorine radical. The present invention is furthermore directed to a process for the preparation of the composition, to the use of the composition in electronic devices and to the device itself.

Claims

1. A composition comprising a light-emitting compound M1 and at least one light-emitting compound M2, wherein M1 and M2 are different from each other and are each a fluorinated metal complex phosphorescent emitter comprising a ligand of any of the following compounds (I-1) to (I-8) ##STR00039## ##STR00040## wherein the atoms from which the arrows point away are coordinated to a metal atom, and where the positions not coordinated to the metal atom, independently of one another, may have a substituent, provided at least one of the positions not coordinated to the metal atom comprises a fluorine radical; wherein the metal atom is Ir; wherein the fluorine radical is a perfluorinated alkyl group having 5 to 15 C atoms, wherein the fluorine radical may be bonded to the ligand via a spacer, and wherein either the absorption spectrum of M1 overlaps with the emission spectrum of M2 or the absorption spectrum of M2 overlaps with the emission spectrum of M1, at least with one of its absorption and emission bands.

2. The composition of claim 1, wherein said composition comprises at least one unfluorinated organic host compound.

3. The composition of claim 2, wherein the organic host compound is a low-molecular-weight compound, dendrimer, oligomer or polymer.

4. The composition of claim 1, wherein the molar ratio M1:M2 is 0.01:1 to 1:0.01.

5. A process for preparing the composition of claim 1, comprising the step of: a) preparing a solution comprising the light-emitting compound M1 and the light-emitting compound M2 in a solvent L1.

6. The process of claim 5, further comprising the steps of: b) preparing a solution comprising an organic host compound in a solvent L2; and c) mixing the two solutions prepared in steps a) and b) together.

7. The process of claim 6, wherein L1 and L2 are identical or miscible with one another.

8. An organic electronic device comprising a cathode, an anode and at least one organic layer, wherein the organic layer comprises the composition of claim 1.

9. The organic electronic device of claim 8, wherein the device is selected from the group consisting of organic electroluminescent devices, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic integrated circuits, organic solar cells, dye-sensitised organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, organic light-emitting electrochemical cells, organic laser diodes, and organic plasmon emitting devices.

10. The composition of claim 1, wherein M1 or M2 is selected from any of the compounds V3 to V6 ##STR00041##

11. The composition of claim 1, wherein the molar ratio M1:M2 is 1:1.

Description

(1) The invention is explained in greater detail by the following examples and figures without wishing it to be restricted thereby.

(2) FIG. 1: Typical structure of an OLED, where the hole-injection layer (HIL) is also called the buffer layer.

(3) FIG. 2: Typical measurement set-up for characterisation of an OLED. The OLEDs are clamped into a holder and provided with spring contacts. A photodiode with eye response filter can be attached directly to the measurement holder in order to exclude influences by extraneous light.

EXAMPLES

(4) The formulae of compounds V1 to V6 prepared in Examples 1 to 6 are depicted below.

(5) ##STR00021## ##STR00022##
Material:

(6) The following compound (TM1) is used as triplet matrix in combination with the compounds of the formula V1 to V6.

(7) ##STR00023##

Example 1

Preparation of Compound V1

(8) ##STR00024##

a) Synthesis of 4-bromophenyl 1-pinacolylboronate

(9) 50.0 g (186 mmol) of 4-n-octyl bromide, 51.9 g (204 mmol) of bispinacolatodiboron, 52.9 g (539 mmol) of potassium acetate are suspended in 800 ml of dimethyl sulfoxide. 4.55 g (5.6 mmol) of 1,1-bis(diphenylphosphino)ferrocenedichloropalladium(II)*DCM are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, 600 ml of ethyl acetate and 400 ml of water are added, and the organic phase is separated off, washed three times with 200 ml of water, dried using sodium sulfate and subsequently evaporated to dryness. The crude product is recrystallised from heptane and finally dried under reduced pressure. The yield is 48.2 g (152 mmol), corresponding to 82.0% of theory.

b) Synthesis of tris[4′-n-octyl-3-(2-pyridinyl-κN)[1,1′-biphenyl]-4-yl-κC]-iridium (III) (compound V1)

(10) 3.4 g (4.0 mmol) of fac-tris[2-(2-pyridinyl-κN)(5-bromophenyl)-κC]-iridium(III), 10.8 g (34 mmol) of 4-bromophenyl 1-pinacolylboronate, 5.02 g (24 mmol) of potassium phosphate are suspended in 100 ml of toluene, 100 ml of dioxane and 111 ml of water. 4 mg (0.02 mmol) of palladium(II) acetate and 35 mg (1.1 mmol) of o-tritolylphosphine are added to this suspension, and the reaction mixture is heated under reflux for 24 h. After cooling, the organic phase is separated off, washed three times with 200 ml of water, filtered through silica gel, dried using sodium sulfate and subsequently evaporated to dryness. The residue is recrystallised from dioxane/ethanol and finally dried under reduced pressure. The yield is 3.64 g (3 mmol), corresponding to 78.0% of theory.

Example 2 to 6

Preparation of Compounds V2 to V6

(11) The following compounds V2 to V6 according to the invention are obtained analogously to the synthesis, described in Example 1, of compound V1 from fac-tris[2-(2-pyridinyl-κN)(5-bromophenyl)-κC]iridium(III) or fac-tris[2-(1-isoquinolinyl-κN)(5-bromophenyl)-κC]iridium(III) and the corresponding boronates:

(12) TABLE-US-00001 Ex. Boronic acid Product Yield V2 75% V3 65% V4 0 60% V5 71% V6 73%

Example 7

Preparation of Compound V7

(13) ##STR00035##

a) Synthesis of 4-(4-n-octylphenylphenylamino)benzaldehyde

(14) 50.0 g (254 mmol) of 4-phenylaminobenzaldehyde, 75.1 g (279 mmol) of p-bromo-n-octylphenyl and 73.1 g (760 mmol) of NaOtBu are suspended in 1 l of p-xylene. 1.1 g (5 mmol) of Pd(OAc).sub.2 and 3.8 ml of a 1M tri-tert-butylphosphine solution are added to this suspension. The reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is separated off, washed three times with 200 ml of water and subsequently evaporated to dryness. The residue is extracted with hot toluene, and employed in the subsequent reaction without further purification. The yield is 81.7 g (212 mmol, 83.6%)

b) Synthesis of Compound V7

(15) 6.0 g (26 mmol) of diethyl (phenyl)methylphosphonate are initially introduced in 70 ml of DMF, 5.54 g of sodium tert-butoxide (58 mmol) are added at about 0° C. under protective gas, and, after a stirring time of 40 minutes at 0° C., a solution of 10.1 g (26 mmol) of 4-(4-n-octylphenylphenylamino)benzaldehyde in 40 ml of DMF is slowly added dropwise at 0° C. After 2 hours, ethanol and water are added dropwise at 5° C., the mixture is stirred overnight at room temperature, and the batch is subsequently extracted by shaking with DCM. The organic phases are separated, washed with water, dried and evaporated in a rotary evaporator. After recrystallisation from acetonitrile, the product is obtained in the form of a slightly yellowish powder. The yield is 9.0 g (20 mmol, 74.5%).

Example 8

Preparation of Compound V8

(16) Compound V8 is obtained analogously to the synthesis of compound V7 described in Example 7.

(17) ##STR00036##

Example 9

Preparation of Polymers P1, P2 and P3

(18) Polymers P2 and P3 and comparative polymer P1 are synthesised by SUZUKI coupling in accordance with WO 2003/048225 A2 using the following monomers (percent data correspond to mol %).

(19) ##STR00037## ##STR00038##

Example 10

Production of OLEDs

(20) The production of an organic light-emitting diode from solution has already been described many times in the literature (for example in WO 2004/037887 A2). In order to explain the present invention by way of example, triplet OLEDs having various combinations of compounds V1 to V6 and matrix TM1 and OLEDs comprising combinations consisting of compounds V7 and V8 and P1 and P2 are produced by means of spin coating.

(21) A typical OLED has the structure depicted in FIG. 1, where the hole-injection layer (HIL) is also called the buffer layer.

(22) The OLEDs are produced using substrates from Technoprint (soda-lime glass) to which ITO (indium tin oxide, a transparent, conductive anode) is applied.

(23) The substrates are cleaned in a clean room with DI water and a detergent (Deconex 15 PF) and subsequently activated by UV/ozone plasma treatment. 80 nm of a buffer layer comprising PEDOT (polythiophene derivative (Baytron P VAI 4083sp.) from H. C. Starck, Goslar, which is supplied as an aqueous dispersion) are then applied by spin coating, likewise in the clean room. The requisite spin rate depends on the degree of dilution and the specific spin-coater geometry (for 80 nm, typically 4500 rpm). In order to remove residual water from the layer, the substrates are dried by heating on a hotplate at 180° C. for 10 minutes. Then, firstly 20 nm of an interlayer (typically a hole-dominated polymer, here P3) and then 80 nm (for redemitting layer) or 65 nm (for blue-emitting layer) of the emitter-containing layers (EML for emissive layer) from solutions (concentration of P3 is 5 g/l in toluene; the compositions of the various EMLs, and the corresponding concentrations are listed in Table 1) are listed under an inert-gas atmosphere (nitrogen or argon). All EML layers are dried by heating at 180° C. for at least 10 minutes. The Ba/Al cathode is then applied by vapour deposition (highly pure metals from Aldrich, in particular barium 99.99%); vapour-deposition units from Lesker or others, typical vacuum level 5×10.sup.6 mbar). In order to protect, in particular, the cathode against air and atmospheric moisture, the device is finally encapsulated and then characterised.

(24) The OLEDs are summarised in Table 2, where OLED1 and OLED4 serve for comparison and OLED2, OLED3 and OLED5 represent the diodes according to the invention.

(25) TABLE-US-00002 TABLE 1 Composition of EML Concentration [wt %] Solvent [mg/ml] OLED1 80% TMM1:10% V1:10% V2 chlorobenzene 24 OLED2 80% TMM1:10% V3:10% V4 chlorobenzene 24 OLED3 80% TMM1:10% V5:10% V6 chlorobenzene 24 OLED4 93% P1:7% V7 toluene 10 OLED5 93% P2:7% V8 toluene 10

Example 11

Characterisation of the OLEDs

(26) In order to characterise the OLEDs, the latter are clamped into holders manufactured especially for the substrate size and provided with spring contacts. A photodiode with eye response filter can be attached directly to the measurement holder in order to exclude influences by extraneous light. A typical measurement set-up is depicted in FIG. 2.

(27) The voltages are typically increased from 0 to max. 20 V in 0.2 V steps and reduced again. For each measurement point, the current through the device and the photocurrent obtained from the photodiode is measured. In this way, the IVL data of the test devices are obtained. Important characteristic quantities are the measured maximum efficiency (“eff.” in cd/A) and the voltage U.sub.100 required for 100 cd/m.sup.2.

(28) In order, in addition, to know the colour and the precise electroluminescence spectrum of the test devices, the voltage required for 100 cd/m.sup.2 is again applied after the first measurement, and the photodiode is replaced by a spectrum measuring head. This is connected to a spectrometer (Ocean Optics USB2000) by an optical fibre. The colour coordinates (ClE: Commission International de l′éclairage, 1931 standard observer) can be derived from the measured spectrum.

(29) In addition, the EQE is also calculated. EQE is an abbreviation and stands for the term “external quantum efficiency”. EQE is defined by the number of photons coming from the device divided by the electrons flowing into the device. The theoretical maximum EQE for singlet OLEDs is typically at about 5% and for triplet OLEDs at a max. about 20%.

(30) The results of the characterisation are summarised in Table 2.

(31) TABLE-US-00003 TABLE 2 Max. eff. Uon U(100) CIE @ Max. [cd/A] [V] [V] 100 cd/m.sup.2 EQE OLED1 2.94 3.4 5.8 0.66/0.34 3.07% OLED2 4.70 3.2 5.4 0.66/0.34 4.63% OLED3 4.22 3.1 5.1 0.66/0.34 3.79% OLED4 1.34 4.4 7.1 0.14/0.15 1.09% OLED5 3.37 3.6 5.8 0.14/0.15 2.75%

(32) As can be seen from the results, OLED2 and OLED3 represent a significant improvement over OLED1 with respect to the efficiency. The same also applies to OLED4 and OLED5. This is caused by the emitting units in OLED2, OLED3 and OLED5 which are closely connected by the F-F interaction (energy transfer by Förster mechanism). Further optimisations can be achieved by different means on the basis of the present technical teaching according to the invention without being inventive. Thus, a further optimisation can be achieved, for example through the use of other emitters in the same or a different concentration.