KR100376320B1 - A red dopant for organic electroluminscene device and the organic electroluminscene device using the same - Google Patents

Abstract

The present invention relates to a red dopant for an organic electroluminescent device and an organic electroluminescent device using the same, and provides at least one red dopant for an organic electroluminescent device among the compounds represented by the following Chemical Formulas 1 to 3 By providing an electroluminescent element, it is possible to provide an organic electroluminescent element having high brightness and excellent thermal stability.

[Formula 1]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl, and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H Or an alkyl group having 1 to 20 carbon atoms.

[Formula 2]

Wherein R ₁ is a C ₁ to C ₂₀ alkyl group, R ₂ , R ₃ is one substituent selected from the group consisting of heteroaryl, aryl, phenyl, furyl, dienyl and pyridyl, and X is S to be.

[Formula 3]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H or An alkyl group having 1 to 20 carbon atoms, Y is NR ₇ and R ₇ is an alkyl group having 1 to 20 carbon atoms.

Description

Red dopant for organic electroluminescent device and the organic electroluminscene device using the same}

[Industrial use]

The present invention relates to a red dopant for an organic electroluminescent device and an organic electroluminescent device using the same, and more particularly, a red dopant for an organic electroluminescent device having excellent thermal stability and brightness and an organic electroluminescent device using the same. Divece; OELD).

[Prior art]

Recently, as the development of the information and communication industry is accelerated, higher performance is required in the field of display devices, which is one of the most important fields. Such displays can be divided into luminescent and non-luminescent. The light emitting display includes a cathode ray tube (CRT), an electroluminescent scene (ELD), an electroluminescent diode (LED), and a plasma display panel (PDP). . Non-light emitting displays include liquid crystal displays (LCDs).

The light emitting and non-light emitting displays have basic performances such as operating voltage, power consumption, brightness, that is, brightness, contrast, response speed, lifetime, and display color. However, among these, liquid crystal displays, which are widely used to date, have problems in response speed, contrast and market dependence among the above basic performances. In this situation, the display using the light emitting diode has a fast response time and is self-luminous so that no back light is required, and the luminance is excellent, and it has various advantages, thus complementing the problems of the liquid crystal display. It is expected to take place as an element.

The light emitting diode is mainly difficult to apply to a large area electroluminescent device because an inorganic material having a crystalline form is used. In addition, in the case of an electroluminescent device using an inorganic material, a driving voltage is required to be 200 V or more, and a price is also disadvantageous. However, since 1987, when Eastman Kodak published a device made of a material having a π-conjugated structure called alumina quinone, research into electroluminescent devices using organic materials has been actively conducted.

The organic electroluminescent device is a self-luminous device for electrically exciting a fluorescent organic compound to emit light.

This device is a conductor device that emits light at low voltage direct current application of several volts, and has excellent characteristics such as high brightness, high speed response, wide viewing angle, surface light emission, and thin color light emission.

Organic EL devices have characteristics that are not found in other displays, and therefore, they are expected to be applied to full color flat panel displays.

The organic EL phenomenon has been known since 1963. However, in 1987, Tang et al. Double stacked organic ultra-thin films and aimed at developing a new display with the announcement of high-brightness organic EL devices of 1000 cd / m2 or more with a DC voltage of 10 volts or less. Became active.

A representative compound of the light emitting layer material of the organic EL device is Alq3. There have been many studies on quinoline complex derivatives, and DTRBi has been found as a blue light emitting layer material.

The doping material is a material that not only improves luminous efficiency but also greatly affects the durability of the device. It is known that organic molecules have a fluorescence quantum yield close to 100% in lean solutions represented by laser dyes.

Traces of such fluorescent quantum yields with high fluorescence quantum dopants in the carrier recombination region and are excited by energy transfer from singlet excitons generated on the host molecule or by carrier traps and recombination directly on the material molecules. It can be expected that the luminous efficiency can be greatly improved.

Coumarin derivatives known as laser pigments, DCM, quinacridine, rubrene and the like are known as red dopants.

At the end of 1996, Pioneer succeeded in commercializing organic EL displays (256 × 64 pixels, green), and color organic EL displays were also announced by Pioneer, Idemitsu, and NEC, respectively. Reached.

However, the red organic dopant used in the organic electroluminescent device has lower quantum efficiency, lower efficiency due to concentration, and lower emission range at different wavelengths than other blue or green light emitting materials. There was a problem that development of a red organic light emitting dopant was difficult due to intentional mismatching.

In addition, research has been conducted in the direction of making EL having excellent thermal stability using organic single molecules having a high Tg value.

The development of red organic light emitting dopants is currently being conducted in various directions. For example, Kodak uses DCJTB of DCM series as a red dopant, and platinum porphyrin (PtOEP) is used as a red dopant at Princeton University. I use it.

It is an object of the present invention to provide a new dopant material containing a coumarin derivative for a high brightness organic electroluminescent device and a method of synthesizing it.

Another object of the present invention is to provide a new dopant material containing a DCM derivative for a high brightness organic electroluminescent device and a method of synthesizing it.

Another object of the present invention is to provide an electroluminescent device which is driven at a low voltage and uses the dopant.

1 is a view schematically showing the structure of an organic EL device according to the present invention.

The present invention to achieve the above object, the present invention

Provided is a red dopant compound for an organic electroluminescent device containing a coumarin derivative represented by the following formula (1).

[Formula 1]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H or It is a C1-C20 alkyl group.

In addition, the present invention provides a red dopant compound for an organic electroluminescent device containing a DCM derivative represented by the following formula (2).

[Formula 2]

Wherein R ₁ is a C ₁ to C ₂₀ alkyl group, R ₂ and R ₃ are one substituent selected from the group consisting of heteroaryl, aryl, phenyl, furyl, thienyl, and pyridyl, and X is S.

In addition, the present invention provides a red dopant for an organic EL device represented by the following formula (3).

[Formula 3]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H or An alkyl group having 1 to 20 carbon atoms, Y is NR ₇ and R ₇ is an alkyl group having 1 to 20 carbon atoms.

In addition, the present invention provides an organic electroluminescent device characterized in that one of the compounds represented by the above formulas (1) to (3) is used.

Hereinafter, the present invention will be described in detail.

The present invention relates to a red-based dopant material containing a coumarin derivative or a DCM derivative for a high brightness organic electroluminescent device, and a method for synthesizing the same. A red red plate having excellent thermal stability and brightness through design and synthesis of a molecular structure To develop new materials.

Red organic monomolecules to solve problems such as low fluorescence quantum efficiency of organic light emitters, concentration dependent quenching, luminescence over a wide wavelength range, and mismatching with host materials It is designed to provide.

The present invention provides one type of red dopant for an organic electroluminescent device among the compounds represented by the following Chemical Formulas 1 to 3.

[Formula 1]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl, and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H Or an alkyl group having 1 to 20 carbon atoms.

[Formula 2]

Wherein R ₁ is a C ₁ to C ₂₀ alkyl group, R ₂ , and R ₃ are one substituent selected from the group consisting of heteroaryl, aryl, phenyl, furyl, thienyl, and pyridyl, X Is S.

[Formula 3]

Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl, and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H Or an alkyl group having 1 to 20 carbon atoms, Y is NR ₇ and R ₇ is an alkyl group having 1 to 20 carbon atoms.

In Formula 1, a coumarin derivative may be introduced into a red dopant to obtain a red dopant for an organic EL device having higher brightness.

R ₁ to R ₄ in Formula 1 are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl and trifluoro It is preferable that it is 1 type of substituents chosen from the group which consists of a methyl group, a pentafluoroethyl group, a perfluoroalkyl group, a heteroaryl group, an aryl group, a phenyl group, and a furyl group.

Meanwhile, the red dopant material represented by Chemical Formula 1 may be synthesized by the following method.

Scheme 1

Scheme 2

Scheme 3

In Scheme 1, methanesulfoniacid and propiolic acid are added to react with piperidine. At this time, the reaction temperature is stirred at about 850 ℃ for 10 hours to react.

The compound prepared in Scheme 1 was reacted for about 6 hours by adding POCl ₃ and DMF (Dimethylformamide) as in Scheme 2.

The red dopant for organic electroluminescent device according to the present invention can be obtained by reacting 3 and 4 with piperidine and ethanol (EtOH) for about 20 hours.

Meanwhile, in Chemical Formula 2, a red dopant for organic electroluminescent device having higher brightness may be obtained by introducing a coumarin derivative into the red dopant.

In Formula 2, R ₁ is preferably an alkyl group of C ₁ to C ₂₀ , R ₂ and R ₃ is a methyl group, ethyl group, propyl group, n-butyl group, isopropyl group, t-butyl group, sec-butyl group 1 selected from the group consisting of t-amyl group, neopentyl group, trifluoromethyl group, pentafluoroethyl group, perfluoroalkyl group, heteroaryl group, aryl group, phenyl group, leuryl group, thienyl group, and pyridyl group It is preferable that it is a substituent of a species.

R ₂ is substituted with X, as can be seen in Chemical Formula 2. It is preferable that said X is S.

The manufacturing method of the red dopant for organic electroluminescent device of Formula 2 is as follows.

Scheme 4

Scheme 5

Scheme 6

As can be seen in Scheme 4, first, DMF, POCl ₃ and the like are added to react with piperidine. At this time, the reaction temperature is reacted for about 6 hours at about 65 ℃.

The reaction product obtained in Scheme 4 is added with methyl iodide (MeI), K ₂ CO ₃ , DMF and the like by Scheme 5 and the mixture is stirred for about 10 hours.

Then, as shown in Scheme 6, piperidine and acetic acid were added and stirred under reflux for 20 hours under nitrogen to obtain the compound of Formula 2.

As described above, in the present invention, a dopant material for organic EL that emits light in the red wavelength range can be obtained, and the compounds have a high glass transition temperature (Tg). Thus, the compounds can expect thermal stability.

Meanwhile, in Formula 3, R ₁ to R ₄ are H, methyl group, ethyl group, propyl group, n-butyl group, isopropyl group, t-butyl group, sec-butyl group, t-amyl group, neopentyl group, and tri It is preferable that it is 1 type of substituents chosen from the group which consists of a fluoromethyl group, a pentafluoroethyl group, a perfluoroalkyl group, a heteroaryl group, an aryl group, a phenyl group, and a furyl group.

The compound of Formula 3 proceeds to the same process as the process for preparing the compound of Formula 1.

The present invention also provides an organic electroluminescent device using one compound of the compounds represented by Formulas 1 to 3 as a red dopant.

As the organic electroluminescent device, Alq3 is preferably used as the red light emitting compound.

Hereinafter, a preferred embodiment of the present invention. However, the following examples are only presented to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Reagents Used

Propiolic acid, methanesulfonic acid, phosphoryl oxychloride, N, N-dimethylformamide, and piperidine are known as Aldrich. Was used. N, N-dimethylformamide was refluxed with a drying agent and refluxed. Further, all solvents including toluene, tetrahydrofuran (THF) and the like were used after purification in the literature. Methylene chloride, ethyl acetate, hydrochloric acid, acetone, magnesium sulfate, etc. used Duksan Chemical.

Confirmation of the structure of the compound prepared in the present invention

The compound prepared in the present invention was confirmed by 1H-NMR, 13C-NMR and FT-IR structure. 1 H-NMR was recorded using a Bruker AM-30 spectrometer and all chemical mobility was reported in ppm based on the solvent. IR spectra were measured on KBr pellets using a Perkin-Elmer spectrometer.

Preparation of Red Dopant with Coumarin Derivative

Example 1

Synthesis Step 1 (Preparation of Compound 1 in Scheme 1; R _One Silver methyl group, R ₂ H, R ₃ H)

9 mmol of the compound of Formula 1, 9 mmol propiolic acid was added to 10 mL of CH ₃ SO ₃ H at room temperature, and the mixture was stirred for 10 hours while maintaining at 850 ° C. After confirming the reaction by TLC, the reaction solution was poured into 100 ml of H ₂ O, and ethyl acetate was extracted. The extracted ethyl acetate layer was washed with saturated aqueous Na ₂ CO ₃ solution. The ethyl acetate solution was removed with water using a MgSO ₄ desiccant, and then the solvent was removed by distillation under reduced pressure. This concentrated solution was separated using column chromatography to obtain the compound of Scheme 1 in Scheme 1, which was light yellow in fluorescence. Yield 30%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.31 (S, 6H), 1.44 (s, 6H), 1.74 to 1.83 (m, 4H), 3.22 (t, 2H), 3.30 (t, 2H) , 6.02 (d, 1H), 7.08 (s, 1H), 7.50 (d, 1H)

Step 2 (Preparation of Compound 3 in Scheme 2; R _One Silver methyl group, R ₂ H, R ₃ H)

1 mL of POCl _{3 was} added to 5 mL of DMF at 0 ° C by syringe. The solution was stirred at room temperature for 1 hour to give a yellow solution. 0.5 g of the material prepared in Step 1 was added to the solution, followed by stirring at room temperature for 6 hours. The solution was poured into 50 ml of H ₂ O to form a solid. This solid was filtered under reduced pressure and washed several times with water. This solid was dried under a vacuum pump for 3 hours to obtain a material of 3 in Scheme 2 which was fluorescing blue. Yield was 95%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.30 (s, 6H), 1.54 (s, 6H), 1.73 to 1.82 (m, 4H), 3.28 (t, 2H), 3.38 (t, 2H) , 7.17 (d, 1H), 8.35 (s, 1H), 9.75 (s, 1H)

Step 3 (Preparation of Compound 5 in Scheme 3)

In the reaction scheme, the materials represented by 3 and 4 were put together with 5 drops of piperidine into 10 ml of ethanol solution and stirred under reflux for 20 hours under nitrogen, followed by TLC. After cooling the reaction solution, the formed solid was separated by filtration under reduced pressure. The solid was washed with ethanol, washed with 10 ml of H ₂ O and 10 ml of diethyl ether, and filtered under reduced pressure, and then dried under a vacuum pump to obtain clean substance 5. Yield was 80%.

1 H-NMR (DMSO-d 6, 300 MHz): δ (ppm) 1.32 (s, 6H), 1.60 (s, 6H), 1.76 to 1.84 (m, 4H), 2.40 (t, 2H), 3.31 to 3.40 ( t, 2H), 6.52 (s, 1H), 6.67 (s, 1H), 7.14 (s, 1H), 7.28 (s, 1H), 7.34 (s, 1H)

Preparation of Red Dopant with DCM Derivative

Synthesis Step 1 (Preparation of Compound 2 in Scheme 4; R _One Silver methyl group)

1 ml of POCl _{3 was} added to 5 ml of DMF at 0 ° C. The solution was stirred at room temperature for 1 hour to give a yellow solution. 10 mmol of the material of Formula 1 was added into the solution and stirred at 65 ° C. for 6 hours. The solution was poured into 50 ml of H ₂ O and extracted with ethyl acetate. The ethyl acetate solution was removed with water using a MgSO ₄ desiccant, and then the solvent was removed by distillation under reduced pressure. This concentrated solution was separated using column chromatography to give a white substance. Yield was 80%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.28 (s, 6H), 1.46 (s, 6H), 1.71 to 1.77 (m, 4H), 3.24 (t, 2H), 3.34 (t, 2H) , 7.06 (s, 1H), 9.40 (s, 1H)

Step 2 (preparation of substance 3 in Scheme 5; R _One Silver methyl group, R ₂ Is methyl group)

10 mmol of the material prepared in Step 1, 13 mmol of methyl iodide, and 20 mmol of K ₂ CO ₃ were added to 5 mL of DMF, and the mixture was maintained at 50 ° C. and stirred for 10 hours. The reaction was confirmed by TLC, and volatiles in the reaction solution were removed by a rotary distiller using a vacuum pump. 100 ml of H ₂ O was added to the concentrated reaction mixture, which was then extracted with a methylene chloride solvent. The methylene chloride solution was removed with water using a MgSO ₄ desiccant, and then the solvent was removed by distillation under reduced pressure. This concentrated solution was separated using column chromatography to give a white substance. Yield was 80%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.26 (s, 6H), 1.41 (s, 6H), 1.67 to 1.74 (m, 4H), 3.22 (t, 2H), 3.31 (t, 2H) , 3.90 (s, 1H), 7.55 (s, 1H), 9.94 (s, 1H)

Step 3 (Preparation of Material 5 in Scheme 6; R _One , R ₂ , R ₃ All methyl groups)

In Scheme 6, 5 mmol of substance 3 and 5 mmol of substance 4 were added together with 5 drops of piperidine and 5 drops of acetic acid into a 10 ml ethanol solution, and the reaction was confirmed by TLC after stirring under reflux for 20 hours under nitrogen. The solvent of the reaction solution was removed with a rotary still, poured into 50 ml of H ₂ O, and extracted with methylene chloride. The methylene chloride solution was removed with a MgSO ₄ desiccant and then the solvent was removed by distillation under reduced pressure. This concentrated solution was separated using column chromatography to obtain a red dopant of the present invention. Yield was 30%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.35 (s, 6H), 1.49 (s, 6H), 1.76 to 1.84 (m, 4H), 2.42 (s, 2H), 3.31 to 3.40 (m, 2H), 3.81 (s, 1H), 6.666 (d, 1H), 6.72 (s, 1H), 6.92 (s, 1H), 7.40 (s, 1H), 7.57 (d, 1H), 7.79 (s, 1H) )

Step 3-1 (Preparation of Material 5 in Scheme 6; R _One , R ₂ Is methyl, R ₃ Is t-butyl)

In Scheme 6, 5 mmol of substance 3 and 5 mmol of substance 4 were added together with 5 drops of piperidine and 5 drops of acetic acid into a 10 ml ethanol solution, and the reaction was confirmed by TLC after stirring under reflux for 20 hours under nitrogen. The solvent of the reaction solution was removed with a rotary still, poured into 50 ml of H ₂ O, and extracted with methylene chloride. The methylene chloride solution was removed with water using a MgSO ₄ desiccant, and then the solvent was removed by distillation under reduced pressure. This concentrated solution was subjected to column chromatography to prepare a red dopant of the present invention. Yield was 85%.

1 H-NMR (CDC13, 300 MHz): δ (ppm) 1.34 (s, 6H), 1.40 (s, 6H), 1.45 (s, 6H), 1.80 to 1.84 (m, 4H), 2.40 (s, 2H) , 3.21 to 3.32 (m, 2H), 3.81 (s, 1H), 6.50 (d, 1H), 6.57 (s, 1H), 6.62 (s, 1H), 7.33 (s, 1H), 7.65 (d, 1H )

Fabrication of Electroluminescent Devices

The structure of the EL device uses ITO (1) as a positive electrode, and there is a buffer layer (2) to compensate the surface of the ITO and to aid in the injection and flow of holes. The material used as the buffer (buffer) is used as the polymer material doped polyaniline (PANI) and doped polyethylene dioxythiophene (PEDOT) and low molecular material alpha-CuPc. PANI and PEDOT produced a thin film in the range of 20 nm to 150 nm by spin coating and alpha-CuPc produced a thin film in the range of 20 nm to 100 nm by vacuum deposition. NPB was vacuum-deposited with a hole transport layer (HTL) 3 and then vacuum-deposited by mixing AlQ3 and the red dopant material prepared in the present invention with an emission layer (EML) 4.

On this thin film, the electron transport layer (ETL) 5 (e.g. AlQ3: thickness ranges from 5 nm to 80 nm), LiF (6) (0.5 nm) to aid electron injection and aluminum metal for cathode (> 100 nm) Was deposited in vacuo to produce a light emitting diode. Film thickness and film growth rate during deposition were controlled using a film thickness monitor. The light emitting layer of the chromophoric compound showed excellent film surface characteristics by irradiation with an optical microscope and an electron microscope.

Investigation of characteristics of electroluminescent device

The light emitting diode I-V characteristics were measured by applying an electric field to the electroluminescent device manufactured as described above. When the red dopant manufactured according to Examples 1 and 2 was used, the turn-on voltage was 5V. . The color purity was (O.65, O.34) and the luminance efficiency was 4 cd / m 2.

The red dopant for the electroluminescent device of the present invention can emit light in the red wavelength range, and the red dopant can have a high glass transition temperature (Tg) to provide a thermally stable organic electroluminescent device.

On the other hand, all simple modifications or changes of the present invention can be easily carried out by those skilled in the art and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (7)

Red dopant compound for organic electroluminescent device containing a coumarin derivative represented by the following formula (1): [Formula 1] Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl, and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H Or an alkyl group having 1 to 20 carbon atoms. delete Red dopant compound for an organic electroluminescent device containing a DCM derivative represented by the formula (2): [Formula 2] Wherein R ₁ is a C ₁ to C ₂₀ alkyl group, R ₂ and R ₃ are one substituent selected from the group consisting of heteroaryl, aryl, phenyl, furyl, thienyl and pyridyl, and X is S to be. delete Red dopant compound for an organic electroluminescent device represented by the following formula (3): [Formula 3] Wherein R ₁ , R ₂ , R ₃ and R ₄ are H, methyl, ethyl, propyl, n-butyl, isopropyl, t-butyl, sec-butyl, t-amyl, neopentyl, trifluoromethyl, C ₁ to C ₂₀ is a straight chain hydrocarbon selected from the group consisting of pentafluoroethyl, and perfluoroalkyl, a is a number from 1 to 5, X is NR ₂ , where R is H Or an alkyl group having 1 to 20 carbon atoms, Y is NR ₇ and R ₇ is an alkyl group having 1 to 20 carbon atoms. delete An electroluminescent device comprising the red dopant compound of any one of claims 1, 3 or 5.