Organic electroluminescence device and flexible OLED display screen

Abstract

This invention relates to the field of electroluminescence technology, specifically to an organic electroluminescent device and a flexible OLED display screen, comprising an anode, a cathode, and an organic layer between the anode and the cathode. The organic layer contains an organic light-emitting compound with the following structural formula: R1-R4 are independently hydrogen, deuterium, and phenyl, respectively, with the hydrogen on the phenyl group either substituted or unsubstituted by deuterium; Z1-Z6 are independently nitrogen or carbon; L is a subaromatic group containing 6-30 carbon atoms; Ar1-Ar4 are independently aromatic groups containing 6-30 carbon atoms. The organic electroluminescent device of this invention exhibits excellent electroluminescence performance and has broad application prospects in emerging flexible electronics fields such as wearable devices, foldable phones, and automotive curved displays.

Description

Technical Field

[0001] This invention relates to the field of electroluminescence technology, specifically to an organic electroluminescent device and a flexible OLED display. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have shown great promise in next-generation display technologies and solid-state lighting due to their superior characteristics such as self-emission, wide viewing angle, high contrast, fast response, and the ability to achieve flexible displays. A typical OLED device structure includes an anode, a cathode, and an organic functional layer located between them. This organic functional layer typically includes a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer.

[0003] When a voltage is applied between the anode and cathode, holes and electrons are injected from the anode and cathode respectively, migrate through their respective transport layers, and finally recombine in the emissive layer to form excitons. The excitons return to the ground state via radiative transitions, thus emitting visible light. The performance of the emissive layer directly determines the device's core performance indicators such as luminous efficiency, color purity, and lifetime.

[0004] In recent years, thermally activated delayed fluorescence (TADF) materials, as third-generation organic light-emitting materials, have become a research hotspot in the field because they can emit light by converting triplet excitons to singlet excitons through an anti-intersystem crossing process without relying on heavy metals, achieving a theoretical internal quantum efficiency of 100%. Boron difluoride complexes, with their excellent photophysical properties and flexibly designable molecular structures, are becoming core materials with great application potential in the field of organic light-emitting diodes, especially playing a key role in future high-definition display technologies. Efficiency roll-off is a common problem for TADF materials, and it is particularly prominent in boron difluoride complex devices.

[0005] The root cause lies in the long-lived triplet excitons: the TADF process relies on long-lived triplet states. Under high current density (i.e., high brightness), excitons accumulate in large numbers, making them highly susceptible to singlet-tritt annihilation and triplet-tritt annihilation, resulting in the non-radiative dissipation of a large number of excitons. The consequence is that the device's practical brightness (e.g., 1000 cd / m²) is limited. 2 The external quantum efficiency under these conditions may decrease by more than 50% compared to the maximum value, which severely limits its application in high-brightness scenarios (such as outdoor displays and lighting). Summary of the Invention

[0006] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes an organic electroluminescent device and a flexible OLED display.

[0007] The technical solution adopted is as follows: An organic electroluminescent device includes an anode, a cathode, and an organic layer between the anode and the cathode, wherein the organic layer contains an organic light-emitting compound, and the organic light-emitting compound has the following structural formula: Among them, R1-R4 are each independently hydrogen, deuterium, and phenyl, and the hydrogen on the phenyl is either substituted by deuterium or not substituted; Z1-Z6 are each independently either nitrogen or carbon; L is a deoxyrheyne containing 6-30 carbon atoms; Ar1-Ar4 are each an aromatic group containing 6-30 carbon atoms.

[0008] In a preferred embodiment of the present invention, R1-R4 are all deuterium; R1-R4 are all hydrogen; one of R1-R4 is phenyl or deuterated phenyl, and the rest are hydrogen.

[0009] Preferably, Z1 to Z6 are all nitrogen atoms. When these positions in the core fused ring framework are all nitrogen atoms, an electronic structure feature with multiple resonance effects can be formed, that is, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are alternately distributed around boron and nitrogen atoms at the atomic level. This special electronic configuration not only reduces the energy level difference between singlet and triplet states, but also the rigid fused ring framework effectively suppresses excited state structural relaxation, resulting in an extremely narrow full width at half maximum (FWHM) of the emission spectrum and exhibiting excellent color purity.

[0010] The linking group L is preferably phenylene or biphenylene. This type of aromatic linking group ensures good conjugation between the core skeleton and the peripheral substituents, and also regulates intermolecular interactions through an appropriate twist angle, avoiding aggregation quenching caused by excessive π-π stacking.

[0011] Ar1 to Ar4 are each preferably phenyl or biphenyl. These aromatic groups can not only regulate the electronic structure and frontier orbital energy levels of the molecule, but also increase the steric hindrance of the molecule, suppress the concentration quenching effect, and improve the thin film morphology and device stability.

[0012] In a more specific embodiment of the present invention, the organic light-emitting compound is selected from any of the following specific compounds, all of which are prepared by a simple synthetic route and are suitable for large-scale production: .

[0013] From a device structure perspective, the organic layer of the organic electroluminescent device described in this invention, from the anode to the cathode, can sequentially include: a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. The light-emitting layer may further comprise a host material, preferably 4,4'-bis(N-carbazolyl)biphenyl (CBP) and / or 1,3-bis(9H-carbazol-9-yl)benzene (mCP). Using these host materials, which possess high triplet energy levels and excellent carrier transport performance, ensures effective energy transfer and exciton confinement.

[0014] The preferred mass ratio of the host material to the organic light-emitting compound of this invention is 90-95:5-10. Within this doping concentration range, guest molecules can be fully dispersed in the host matrix, achieving efficient host-guest energy transfer while effectively suppressing concentration quenching and exciton annihilation caused by excessively high doping concentrations, thereby obtaining optimal external quantum efficiency and brightness stability of the device. Example data show that the device achieves the highest external quantum efficiency when the doping concentration is 7.5 wt%, confirming the optimality of this range.

[0015] A series of experiments show that the preferred anode material is indium tin oxide (ITO); the hole injection layer material can be poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS); the preferred hole transport layer material is 4,4',4"-tris(carbazole-9-yl)triphenylamine (TCTA); the preferred electron transport layer material is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi); the preferred electron injection layer material is lithium 8-hydroxyquinoline (Liq); and the preferred cathode material is aluminum (Al). These functional layers are prepared using conventional methods in the field, such as spin coating or vacuum evaporation. The processes are mature, highly reproducible, and facilitate industrialization.

[0016] The present invention also provides a flexible OLED display screen comprising any of the aforementioned organic electroluminescent devices. By fabricating the device on a flexible substrate, bendable and foldable display devices can be realized, further expanding application scenarios.

[0017] The beneficial effects of this invention are: The organic light-emitting compound in the organic electroluminescent device provided by this invention integrates a spiro[fluorene-9,7'-dibenzo[acrylidine]] core, an electron-deficient triazine group, and an electron-rich carbazole group into a highly rigid and electronically coordinated molecular system. The spiro[fluorene-9,7'-dibenzo[acrylidine]] core possesses a unique helical conjugated structure, with two nearly perpendicular π-planes intersecting at the spirocarbon atom. This not only provides significant steric hindrance, effectively preventing face-to-face π-π stacking of the light-emitting molecules in the solid state, thus strongly suppressing aggregation-induced quenching, but also promotes intramolecular electron delocalization through the spatial conjugation effect. The triazine group acts as an electron acceptor, and the carbazole group as an electron donor, connected by the spirocyclic core to form an intramolecular charge-transfer excited state. This symmetrical donor-acceptor topology significantly reduces the singlet-tritium energy level difference, promoting antisystem crossing, and further balances carrier transport in the light-emitting layer by regulating the molecular frontier orbital energy levels. The excellent hole transport capability of the carbazole group and the good electron transport properties of the triazine unit are integrated intramolecularly, enabling excitons to form and recombine efficiently in the luminescent layer, directly contributing to a significant improvement in external quantum efficiency. The excellent performance of the device is a concrete manifestation of this synergistic effect in the electroluminescence process.

[0018] Another important structural feature of the organic light-emitting compound of this invention is the presence of an NBO six-membered chelate ring and fluorine atoms directly bonded to boron atoms. This ring system exhibits extremely high rigidity and coplanarity. This rigidity fundamentally suppresses the non-radiative deactivation channels of the excited state. Simultaneously, the two fluorine atoms bonded to the boron atom play multiple positive roles. First, the strong electronegativity of the fluorine atom effectively lowers the LUMO energy level of the entire molecule through an inductive effect, enhancing electron injection and transport capabilities, which is beneficial for improving charge balance and widening the exciton recombination region. Second, the low polarizability of the CF bond and the CF···HC hydrogen bond network that may form with other molecules improve the microstructure of the doped film and reduce defects and non-radiative centers. Third, the small atomic radius of the fluorine atom ensures the close packing of the chelate ring, without causing additional steric hindrance. This perfect combination of the NBO six-membered ring and fluorine atoms enables the compound of this invention to possess both high exciton utilization and excellent film-forming properties, which is one of the fundamental reasons for the high external quantum efficiency of the device.

[0019] The organic light-emitting compounds synthesized in this invention possess high molecular weight and a rigid framework, with thermal decomposition temperatures significantly higher than those of conventional small molecules. In thermogravimetric analysis (TGA) tests, representative compounds exhibited a 5% weight loss temperature exceeding 450°C under a nitrogen atmosphere, demonstrating excellent thermal stability. This ensures that the devices do not undergo material decomposition or performance degradation during long-term operation or under high-temperature environments. Furthermore, these compounds exhibit good solubility in common organic solvents (such as chlorobenzene and toluene), allowing for solution spin-coating to form films, compatible with large-area, low-cost manufacturing solutions, and particularly suitable for flexible substrates and inkjet printing technology.

[0020] Flexible OLED displays incorporating the devices of this invention maintain stable photoelectric output and color quality even when bent or folded, thanks to the superior performance of the luminescent material itself and the overall optimization of the device structure. The rational combination of a rigid core framework and flexible peripheral groups endows the thin film with excellent mechanical flexibility, reducing microcracks and performance degradation caused by stress concentration. Therefore, the technical solution of this invention is not only competitive in the field of rigid displays but also has broad application prospects in emerging flexible electronics fields such as wearable devices, foldable phones, and automotive curved displays. Attached Figure Description

[0021] Figure 1 This is the synthetic route diagram for the organic light-emitting compound in Example 1.

[0022] Figure 2 This is the synthetic route diagram for the organic light-emitting compound in Synthesis Example 2. Detailed Implementation

[0023] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0024] Synthesis example 1: A method for preparing an organic light-emitting compound: S1: Under nitrogen protection, add SM1 (10 mmol, 1 eq), SM2 (21 mmol, 2.1 eq), 80 ml toluene, 20 ml ethanol, potassium carbonate (50 mmol, 5 eq), 10 ml water, and tetra(triphenylphosphine)palladium (0.3 mmol, 3% eq) to a reaction flask equipped with a condenser. After the addition is complete, place the flask in an oil bath at 80 °C and keep it warm for 6 h. Take a sample and detect the reaction is complete by HPLC. Add water to the reaction solution, filter, wash the filter cake with water and ethanol, dry it under vacuum at 85 °C, and then purify it with toluene to obtain P1 with a yield of 52.1%.

[0025] S2: Under nitrogen protection, P1 (5 mmol, 1 eq), 4-bromoaniline (5 mmol, 1 eq), 50 ml of anhydrous toluene, and sodium tert-butoxide (10 mmol, 2 eq) were added to a reaction flask equipped with a condenser. After the addition was complete, tris(dibenzylacetone)palladium (0.1 mmol, 2% eq) and Xantphos ligand (0.2 mmol, 4% eq) were added. The mixture was placed in a 90°C oil bath and reacted for 18 h. The reaction was detected by TLC. The reaction solution was quenched with saturated sodium chloride solution, extracted three times with ethyl acetate, and the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1-1:1 gradient elution) to obtain P2 in a yield of 38.5%.

[0026] S3: Under nitrogen protection, P2 (1 mmol, 1 eq), salicylaldehyde (1.5 mmol, 1.5 eq), 50 mL of anhydrous toluene, and 4 Å (5 g) molecular sieve were added to the reaction flask. After the addition was complete, the flask was refluxed in an oil bath at 110 °C for 12 h. The reaction was detected by TLC. The molecular sieve was removed by hot filtration. The filtrate was concentrated to dryness under reduced pressure. The residue was recrystallized with anhydrous ethanol, filtered, and the filter cake was washed with cold ethanol and dried under vacuum at 60 °C to obtain P3 with a yield of 78.6%.

[0027] S4: Under nitrogen protection, P3 (0.5 mmol, 1 eq) and 50 mL of anhydrous dichloromethane were added to a reaction flask equipped with a condenser. After the addition was complete, the mixture was cooled to 0°C, and the boron trifluoride diethyl ether complex (0.75 mmol, 1.5 eq) was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 2 h, then heated to 40°C and reacted for 4 h. A sample was taken for TLC to detect the completion of the reaction. The reaction solution was cooled to 0°C, and quenched by slowly adding saturated sodium bicarbonate solution. The mixture was separated, and the organic phase was washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and concentrated to dryness under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1-1:2 gradient elution) to obtain the organic luminescent compound with a yield of 68.5%. MS (ESI, m / z): [M+H] + =1468.27, elemental analysis result (molecular formula C 100 H 61 OBF2N 10Theoretical values: C, 81.85; H, 4.19; O, 1.09; B, 0.74; F, 2.59; N, 9.55. Test values: C, 81.55; H, 4.29; O, 1.24; B, 0.72; F, 2.41; N, 9.45. HPLC purity 99.3%, thermogravimetric temperature Td 465.3℃. Thermogravimetric temperature Td is the temperature at which 5% weight is lost in a nitrogen atmosphere, determined on a thermogravimetric analyzer at a nitrogen flow rate of 10 mL / min.

[0028] Synthesis example 2: A method for preparing an organic light-emitting compound: The synthesis methods for S1 and S2 are the same as in Synthesis Example 1; S3: Under nitrogen protection, P2 (1 mmol, 1 eq), 2-hydroxy-5-phenylbenzaldehyde (1.5 mmol, 1.5 eq), 50 mL of anhydrous toluene, and 4 Å (5 g) of molecular sieve were added to the reaction flask. After the addition was complete, the flask was refluxed in an oil bath at 110 °C for 12 h. The reaction was detected by TLC. The molecular sieve was removed by hot filtration. The filtrate was concentrated to dryness under reduced pressure. The residue was recrystallized with anhydrous ethanol, filtered, and the filter cake was washed with cold ethanol and dried under vacuum at 60 °C to obtain P3 with a yield of 73.3%.

[0029] S4: Under nitrogen protection, P3 (0.5 mmol, 1 eq) and 50 mL of anhydrous dichloromethane were added to a reaction flask equipped with a condenser. After the addition was complete, the mixture was cooled to 0°C, and boron trifluoride diethyl ether complex (0.75 mmol, 1.5 eq) was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 2 h, then heated to 40°C and reacted for 4 h. A sample was taken for TLC to detect the completion of the reaction. The reaction solution was cooled to 0°C, and saturated sodium bicarbonate solution was slowly added to quench the reaction. The mixture was separated, and the organic phase was washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and concentrated to dryness under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1-1:2 gradient elution) to obtain the organic luminescent compound with a yield of 60.2%. MS (ESI, m / z): [M+H] + =1544.03, elemental analysis result (molecular formula C 106 H 65 OBF2N 10Theoretical values: C, 82.48; H, 4.24; O, 1.04; B, 0.70; F, 2.46; N, 9.07. Test values: C, 82.21; H, 4.36; O, 1.18; B, 0.64; F, 2.32; N, 8.94. HPLC purity 99.1%. Thermogravimetric temperature Td 468.5℃. Thermogravimetric temperature Td is the temperature at which 5% weight is lost in a nitrogen atmosphere, determined on a TGAN-1000 thermogravimetric analyzer at a nitrogen flow rate of 10 mL / min.

[0030] Example 1:

[0031] An organic electroluminescent device, the structure of which is as follows: ITO anode / PEDOT: PSS (45nm) hole injection layer / TCTA (20nm) hole transport layer / organic light-emitting compound in the above synthesis example 1: mCP (30nm) light-emitting layer / TPBi (20nm) electron transport layer / Liq (2nm) electron injection layer / Al (150nm) cathode.

[0032] The method for fabricating the above-mentioned organic electroluminescent device is as follows: PEDOT:PSS was spin-coated onto a pre-cleaned and oxygen plasma-treated ITO (indium tin oxide) anode substrate, and then dried to obtain a hole injection layer with a thickness of 45 nm. TCTA (4,4',4''-tris(carbazole-9-yl)triphenylamine) was dissolved in chlorobenzene and then spin-coated onto the hole injection layer, followed by drying to obtain a hole transport layer with a thickness of 20 nm. mCP (1,3-bis(9H-carbazole-9-yl)benzene) was mixed with the organic light-emitting compound from Synthesis Example 1 at a mass ratio of [missing information]. A mixture of 92.5 and 7.5 was dissolved in chlorobenzene and then spin-coated onto the hole transport layer. After drying, a thin layer with a thickness of approximately 30 nm was obtained. The subsequent TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene) electron transport layer, Liq (lithium 8-hydroxyquinoline) electron injection layer, and Al (aluminum) cathode were all obtained by vacuum evaporation. Their evaporation rates were approximately 2 Å / s, 0.5 Å / s, and 4 Å / s, respectively; and their thicknesses were 20 nm, 2 nm, and 150 nm, respectively.

[0033] Example 2:

[0034] The process is essentially the same as in Example 1, except that mCP (1,3-bis(9H-carbazole-9-yl)benzene) and the organic light-emitting compound in Synthesis Example 1 are in a mass ratio of 90:10.

[0035] Example 3:

[0036] The process is essentially the same as in Example 1, except that the mass ratio of mCP (1,3-bis(9H-carbazole-9-yl)benzene) to the organic light-emitting compound in Synthesis Example 1 is 95:5.

[0037] Example 4:

[0038] The experiment was essentially the same as in Example 1, except that the mass ratio of mCP (1,3-bis(9H-carbazole-9-yl)benzene) to the organic light-emitting compound in Synthesis Example 2 was 92.5:7.5.

[0039] Example 5:

[0040] The process is essentially the same as in Example 1, except that the mass ratio of mCP (1,3-bis(9H-carbazole-9-yl)benzene) to the organic light-emitting compound in Synthesis Example 2 is 90:10.

[0041] Example 6:

[0042] The process is essentially the same as in Example 1, except that the mass ratio of mCP (1,3-bis(9H-carbazole-9-yl)benzene) to the organic light-emitting compound in Synthesis Example 2 is 95:5.

[0043] Comparative example: The synthesis is basically the same as in Example 1, except that the organic light-emitting compound in Example 1 is replaced with a boron difluoride complex with the following structure.

[0044] Boron difluoride complexes Performance testing: The current, voltage, luminance, and emission spectrum characteristics of organic electroluminescent devices (OLEDs) were simultaneously tested using a spectral scanning luminance meter and a digital source meter system. Performance testing of the OLEDs was conducted at room temperature and under ambient atmosphere. The external quantum efficiency (EQE) of the OLEDs was calculated based on the Lambaugh distribution of emission, using current density, luminance, and electroluminescence spectrum combined with the apparent function.

[0045] The electroluminescence performance data of the organic electroluminescent devices in Examples 1-6 and the comparative examples are shown in Table 1 below: As shown in Table 1 above, the organic electroluminescent device of the present invention exhibits good electroluminescence performance.

[0046] The comparison of Examples 1-6 shows that a doping concentration of 7.5% is appropriate, the host-guest energy transfer is sufficient, and the intermolecular distance is sufficient to suppress direct interaction. The increase in concentration leads to a shortening of the guest intermolecular distance, π-π stacking or enhanced multi-molecular interaction, causing aggregation quenching. If the concentration is too low, excitons cannot be completely transferred from the host mCP to the luminescent guest, resulting in host leakage or insufficient guest capture.

[0047] A comparison of Examples 1 and 4 shows that the introduction of additional phenyl groups further expands the conjugated system, increases the oscillator strength of the molecules, and makes the recombination of excitons in the emitting layer more balanced. Therefore, at the same doping ratio, the external quantum efficiency of the device in Example 1 is higher than that of the device in Example 4. The device in Example 4, by introducing phenyl groups to expand the conjugated system, although resulting in a slight redshift in the spectrum, improves the oscillator strength and rigidity, achieving a higher EQE and a lower roll-off while maintaining pure blue light, thus achieving the optimal balance between color purity and efficiency.

[0048] Comparative example in practical brightness (1000 cd / cm) 2 The external quantum efficiency plummets. This drastic drop is due to severe singlet-triplet annihilation (STA) and triplet-triplet annihilation (TTA), which not only "eat up" efficiency but also cause disorder in the carrier recombination region and dissipation of high-energy exciton energy, manifested as a significant broadening of the spectrum and a shift of the color coordinates towards longer wavelengths.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An organic electroluminescent device, characterized in that, It includes an anode, a cathode, and an organic layer between the anode and the cathode, wherein the organic layer contains an organic light-emitting compound, the structural formula of which is as follows: Among them, R1-R4 are each independently hydrogen, deuterium, and phenyl, and the hydrogen on the phenyl is either substituted by deuterium or not substituted; Z1-Z6 are each independently either nitrogen or carbon; L is a deoxyrheyne containing 6-30 carbon atoms; Ar1-Ar4 are each an aromatic group containing 6-30 carbon atoms.

2. The organic electroluminescent device as described in claim 1, characterized in that, R1-R4 are all deuterium; R1-R4 are all hydrogen; one of R1-R4 is a phenyl or deuterated phenyl, and the rest are hydrogen.

3. The organic electroluminescent device as described in claim 1, characterized in that, Z1-Z6 are all nitrogen.

4. The organic electroluminescent device as described in claim 1, characterized in that, L represents phenylene or biphenylene.

5. The organic electroluminescent device as described in claim 1, characterized in that, Ar1-Ar4 are phenyl or biphenyl.

6. The organic electroluminescent device as described in claim 1, characterized in that, The organic light-emitting compound is any one of the following compounds: 。 7. The organic electroluminescent device as described in claim 1, characterized in that, The organic layer comprises, in sequence: a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer, with the organic light-emitting compound located in the light-emitting layer.

8. The organic electroluminescent device as described in claim 7, characterized in that, The light-emitting layer also includes a host material, which is 4,4'N,N' biscarbazolyl biphenyl and / or 1,3-bis(9H-carbazo-9-yl)benzene.

9. The organic electroluminescent device as described in claim 8, characterized in that, The mass ratio of the host material to the organic light-emitting compound is 90-95:5-10.

10. A flexible OLED display screen, characterized in that, An organic electroluminescent device comprising any one of claims 1-9.

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