JP2002164177A - Liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a liquid crystal element that has a good electron current property by making doping on a liquid crystal efficiently and stably. SOLUTION: The element is constructed by interposing between the electrodes a liquid crystal layer made of a liquid crystal composite in which an electron donative compound or an electron accepting compound that has K electron conjugate structure is doped on a smectic liquid crystal or a discotic liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device utilizing the self-alignment property and electric conductivity of a liquid crystal.
More specifically, the present invention relates to an organic electroluminescence device using a liquid crystal for a carrier transport layer, and a liquid crystal device used for an electronic device such as a transistor or a diode utilizing the conductivity of the liquid crystal.

[0002]

2. Description of the Related Art Organic electroluminescent elements (hereinafter referred to as "organic EL elements") are being intensively studied for application as light-emitting elements having high-speed response and high efficiency.
Its configuration is described, for example, in Macromol. Symp. 12
5, 1-48 (1997). FIG. 1 shows a schematic cross-sectional view of the basic configuration. In the figure, 1 is a metal electrode, 2 is a light emitting layer, 3 is a hole transport layer, 4 is a transparent electrode, 5
Is a transparent substrate, and 6 is an electron transport layer.

As shown in FIG. 1, an organic EL device generally comprises a transparent substrate 5 and a laminated body in which a single layer or a plurality of organic layers are sandwiched between a transparent electrode 4 and a metal electrode 1. Become. In FIG. 1A, the organic layer includes a light emitting layer 2 and a hole transport layer 3. As the transparent electrode 4, ITO having a large work function is used.
(Indium tin oxide) or the like is used to provide good hole injection characteristics from the transparent electrode 4 to the hole transport layer 3. As the metal electrode 1, aluminum,
A metal material having a small work function, such as magnesium or an alloy using them, is used to provide good electron injection into an organic layer. The thickness of these electrodes is about 50 to 200 nm.

In the organic EL device shown in FIG. 1A, the light emitting layer 2 is usually provided with an aluminum quinolinol complex derivative having electron transporting properties and light emitting characteristics [typically, an Al quinolinol complex derivative shown below.
q (tris (8-quinolalit) aluminum). ] Is used. The hole transport layer 3 is made of a material having an electron donating property such as a triphenyldiamine derivative [typically, αNPD (bis [N- (1-naphthyl) -N-phenyl] benzidine) shown below]. Is used.

[0005]

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The organic EL device having the above structure exhibits rectifying properties. When an electric field is applied such that the metal electrode 1 serves as a cathode and the transparent electrode 4 serves as an anode, electrons are emitted from the metal electrode 1 to the light emitting layer 2. Holes are injected from the transparent electrode 4. The holes and electrons injected into the light emitting layer 2 recombine in the light emitting layer 2 to generate excitons and emit light. At this time, the hole transport layer 3 functions as an electron blocking layer, and the recombination efficiency at the interface between the light emitting layer and the hole transport layer is increased, thereby improving the luminous efficiency.

Further, in the configuration of FIG.
(A) an electron transport layer 6 between the metal electrode 1 and the light emitting layer 2;
Is provided. In this structure, efficient light emission can be performed by separating light emission and electron / hole transport to form a more effective carrier blocking structure. As the electron transport layer 6, for example, an oxadiazole derivative or the like can be used.

The thickness of the above-mentioned organic layers (the light-emitting layer 2, the hole transport layer 3, and the electron transport layer 6) is 50 to 500 nm in total of two or three layers.

In the above-mentioned organic EL device, there is a problem that the performance of injecting electrons or holes from the electrodes determines the level of luminance. When an amorphous material such as Alq or αNPD described above is used, it is considered that it does not necessarily have sufficient carrier injection characteristics due to the problem of the interface between the electrode and the organic layer.

Therefore, it is expected that a liquid crystal material is used as a new charge transport layer or light emitting layer having high carrier injection performance and high mobility.

As a liquid crystal material having a high carrier transport ability,
A liquid crystal exhibiting a discotic liquid crystal phase or a smectic phase having a high degree of order, that is, a discotic liquid crystal or a smectic liquid crystal may be used.

As a discotic liquid crystal material, for example,
If, for example, the following triphenylene-based liquid crystal group
(Advanced Materials, 1996.
8, No. 10). Side chains of the following liquid crystal compounds 1-4-
R is -OC_FourH₉Or -OC _FiveH₁₁, -OC₆H₁₃Al
Coxy group, -SC₆H₁₃Thioether group has high carry
A mobility (10^-1-10^-3cm / Vs) hole transport capacity
It is known to have These are discotic
The columnar liquid crystal molecules show
Having a rich π-electron skeleton
Because the groups are oriented so that they overlap each other, triphenylene
Good hole transport ability can be obtained via the thiol group. Liquid crystal compound
The object 5 was developed by the present inventors, etc.
By polyfluorinating chains, discotic liquid crystal
When the temperature range shifts to the lower temperature side compared to the unsubstituted one
At the same time, the ionization potential decreases. Liquid crystal compound
7 is an example in which the liquid crystal skeleton is dibenzopyrene, which is also
A compound that exhibits a discotic columnar phase
You.

[0013]

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[0014]

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Other discotic liquid crystal skeletons include phthalocyanine derivatives, naphthalocyanine derivatives,
Examples include a tolcene derivative, a hexabenzocoronene derivative, and a benzoquinone derivative.

Further, typical smectic liquid crystal materials include, for example, liquid crystal compounds 8 to 11 shown below (Applied Physics, Vol. 68, No. 1, p26 (199)
9)).

[0017]

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The liquid crystal compound 8 (having a smectic A phase), which is a phenylbenzothiazole derivative, has a hole transporting property, and the liquid crystal compound 9 (having a smectic A phase and a smectic E phase), which is a phenylnaphthalene derivative, An ordered smectic E phase exhibits higher mobility) is a hole-electron ambipolar transport material. Each of the liquid crystal compounds 8 and 9 is 10 ⁻³ cm / Vs.
The above high mobility is shown.

Liquid crystal compounds other than the skeletons listed here may be any as long as they have a rod-like skeleton and exhibit a smectic liquid crystal phase.

By using these liquid crystal compounds in the electron and hole transport layers shown in FIG. 1, it is expected that good productivity and device performance will be exhibited.

The characteristics of the liquid crystal material having a carrier transporting property can be summarized as follows: high carrier mobility by self-alignment of bulk; high carrier injection property by orientation of π-electron conjugate plane to an electrode interface; have.

Further, the present inventors have examined whether more efficient light emission can be obtained by not only injecting carriers from the electrodes but also generating carriers in the organic layer. Until now, several groups have been studying doping a carrier transporting material with an electron accepting or donating compound for an organic layer. For example, (1) App
led Physics Letter, vol. 7
2, No. 17, p. 2147 (1998) Yamam
oto et al. (2) Applied Physics Le
tter, vol. 73, No. 20, p. 2866
(1998) Kido et al.

In the above document (1), a polymer material is used for the hole transport layer, and a salt containing SbCl ₆ ^- is added to the hole transport layer for 20 mol.
By mixing 1%, holes are generated in the hole-transporting polymer material, the carrier density is improved, and high-emission luminance radiation has been successfully achieved. Further, in the above-mentioned document (2), the electron transporting layer is doped with Li metal to improve the electron injection property.

Further, as an example of doping the liquid crystal,
(3) J.I. Am. Chem. Soc. , Vol. 11
6, No. 23, p. 10808 (1994) Bode
(4) J. N. et al. Material Science: M
materials in Electronics,
5, p. 83 (1994).

The above-mentioned reference (3) discloses that a discotic liquid crystal material having a tricycloquinazoline skeleton contains 6 mol of potassium.
By doping with 1%, an n-type semiconductor whose main carriers are electrons is produced. Also, in the above reference (4), the discotic liquid crystal having a triphenylene skeleton has Al
By doping with Cl ₃ , a p-type semiconductor whose main carriers are holes is produced.

[0026]

When an electronic device having a compound layer in which a liquid crystal compound is doped with an inorganic compound as described above is constructed, only electronic carriers (holes or electrons) are generated by an externally applied electric field. Not
The ionized (anionized or cationized) dopant moves in the liquid crystal compound, and an ionic current flows.
The ionic current is caused by the movement of the dopant itself, and the reversibility of the current characteristics is poor. Thus, there remains a serious problem not only in initial performance but also in durability. In particular, in the case of a liquid crystal compound, since it has the property of a liquid, the problem of ionic current is much greater than that of an amorphous or polymer material. The elements mentioned in the above-mentioned documents (3) or (4)
Since the device is a single-layer liquid crystal layer and only measures basic voltage-current characteristics, problems will become apparent even if ionic and electronic currents coexist. do not do.

In view of the above problems, an object of the present invention is to develop an efficient and stable liquid crystal doping technique, and to construct a good electronic device using the liquid crystal composition obtained by the technique. It is to provide a possible liquid crystal element.

[0028]

According to a first aspect of the present invention, in a liquid crystal device having a plurality of layers disposed between a pair of electrodes, at least one of the plurality of layers includes a compound of two or more components. Comprising a liquid crystal layer using a liquid crystal composition having an electron carrier transporting ability, wherein at least one component is an electron donating compound or an electron accepting compound having a π electron conjugated structure. Element.

The liquid crystal device of the present invention includes the following configuration as a preferred embodiment. At least one component of the compound constituting the liquid crystal composition is a liquid crystal compound which exhibits a liquid crystal phase by itself. The concentration of impurities contained in the liquid crystal compound is 1% by weight or less as measured by high performance liquid chromatography. The liquid crystal layer is formed by co-evaporation of a liquid crystal composition by a vacuum evaporation method, or formed by applying a liquid crystal composition by a spin coating method. The liquid crystal composition is in a smectic liquid crystal phase or discotic liquid crystal phase. A plurality of liquid crystal layers are provided.

In the liquid crystal device of the present invention, the following configuration is also included as a preferred embodiment. One liquid crystal layer contains the liquid crystal composition containing the electron donating compound having the π-electron conjugate structure, and another liquid crystal layer contains the electron accepting compound having the π-electron conjugate structure. The ionization potential of the above electron donating compound is represented by I
And _P ^D, when the ionization potential of the other components of the liquid crystal composition and I _P ^LC, for the electron-donating compound, to satisfy the following equation.

[0031] I _P ^D -I _P ^LC <-0.3eV the ionization potential of the electron-accepting compound and I _P ^A, the ionization potential of the other components of the liquid crystal composition I
_Assuming ^PLC , the electron accepting compound must satisfy the following formula.

[0032] I _P ^A -I _P ^LC> 0.3eV to function as an organic electroluminescent device. A carrier transport layer made of a different compound that transports the same carrier species as the main carrier species transported by the liquid crystal layer is provided in contact with the liquid crystal layer.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a high-performance liquid crystal device utilizing good current characteristics derived from the degree of order by utilizing the self-organization of liquid crystal. In the present invention, a liquid crystal element is formed using a liquid crystal composition including a plurality of compounds.

Here, the case where the liquid crystal compound is applied to various semiconductors will be considered in comparison with a Si crystal semiconductor. The Si crystal has a band gap of about 1.1 eV.
By mixing an electron-donating or electron-accepting atom, the density of holes in the conduction band and the valence band is increased to generate free carriers. Thus, elements having various functions are constituted by various combinations such as a PN junction.

On the other hand, liquid crystal compounds generally have a band gap of 2 to 3 eV, and have a low density of thermally excited free carriers. In the case of an organic EL element, a liquid crystal compound having a small free carrier density can be used since electrons and holes are injected from the outside and carriers are used. However, in order to further increase the efficiency, the liquid crystal compound is doped. Thus, high current density and high luminance can be realized.

That is, in order to widen the range of application of the liquid crystal compound, it is necessary to mix p-type or n-type semiconductors by mixing electron-donating or electron-accepting compounds at an appropriate ratio.

FIG. 2 shows an example of a transistor using the liquid crystal element of the present invention.
tal Oxide Semiconductor (FET) Field Effect Transistor
or) A schematic cross-sectional view of the device is shown. In the figure, 21 is a gate electrode, 22 is a gate insulating film, 23 is an organic active layer, 24 is a drain electrode, and 25 is a source electrode. In this device, the organic active layer 23 is made of a liquid crystal composition. Also,
As for the other members, the members used for the conventional MOS FET device can be used as they are. Organic active layer 23
As the liquid crystal composition constituting the above, for example, an n-type semiconductor layer obtained by mixing a fixed amount of an electron donating compound is used.
In this configuration, a current can flow between the source electrode 25 and the drain electrode 24 by applying a positive voltage equal to or more than a certain value to the gate electrode 21.

FIG. 3 shows an example of a diode using the liquid crystal element of the present invention. In the figure, reference numerals 31 and 34 denote electrodes, between which a p-type semiconductor layer 33 and an n-type semiconductor layer 34 are narrowed. I have it. In this device, the electrodes 31 and 34 are made of a member constituting a conventional diode, the p-type semiconductor layer 33 and the n-type semiconductor layer 34 are both made of a liquid crystal composition,
The p-type semiconductor layer 33 contains an electron-accepting compound, and the n-type semiconductor layer 34 contains an electron-donating compound. With this configuration, a rectifying property in which a current flows when an electric field is applied between the electrodes 31 and 34 using the electrode 31 as a positive electrode is exhibited.

Further, in the liquid crystal device of the present invention, the impurities contained in the liquid crystal layer act as carrier traps, and satisfactory characteristics cannot be obtained if a certain amount or more of impurities are mixed. The impurities include organic substances generated in the synthesis process, and can be removed by recrystallization or sublimation purification. Keeping the impurity concentration below a certain level is indispensable for producing a high-performance device. In particular, in the case of doping, the mixing of impurities other than the dopant has a great effect, and the concentration of the impurities other than the dopant greatly affects the device characteristics. Therefore, in the present invention, the allowable amount of impurities contained in the liquid crystal compound before doping is 1% by weight or less as measured by high performance liquid chromatography (HPLC).

Specific examples of the above-mentioned dopant of the liquid crystal compound are shown below. The dopant is divided into an inorganic type and an organic type (system having a π-electron conjugate structure). The electron donating compound has a small ionization potential, and the electron accepting compound has a large electron affinity.

In the present invention, one component of the liquid crystal composition containing two or more compounds and having an electron carrier transporting ability is an electron donating compound or an electron accepting compound having a π-electron conjugated structure.

[0042] Here, the ionization potential of the electron donating compound and I _P ^D, when the ionization potential of the other components of the liquid crystal composition and I _P ^LC, electron-donating compound preferably satisfies the following formula .

[0043] I _P ^D -I _P ^LC <-0.3eV also the ionization potential of the electron-accepting compound I _P ^A
Then, the electron accepting compound preferably satisfies the following formula.

[0044] I _P ^A -I _P ^LC> 0.3eV electron donor compound which satisfies these equations, generation of free carriers is achieved stably by adopting the electron-accepting compound.

[Electron-donating compound] Inorganic metal such as Li, Na, K, Cs, etc. Organic system (system having π electron conjugate structure)

[0046]

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[Electron-Accepting Compound] Inorganic Br ₂ , I ₂ , Cl ₂ , BF ₃ , PF ₅ , SbF ₅ , SO ₃ ,
Organic system (system having π-electron conjugate structure) such as FeCl ₃ and AlCl ₃

[0048]

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The inorganic dopant has a relatively small volume relative to the liquid crystal compound and the organic dopant. The liquid crystal compound takes a form in which a skeleton portion and a side chain portion are laminated, and particularly, an ionized dopant existing in the side chain portion easily moves in accordance with an electric field, and an ion current cannot be ignored.

On the other hand, the organic dopant has a volume approximately equal to or larger than the skeletal system of the liquid crystal compound serving as a host, and causes charge transfer by π-electron interaction.
Generate free carriers. Therefore, the liquid crystal of the host and the dopant form a charge transfer complex that binds by a relatively strong interaction. Therefore, the organic dopant does not easily move, and the ionic current becomes negligible, so that an element having high durability and reliability can be obtained. Further, as the dopant, the liquid crystal compound as described above can be used.

It is also preferable to form an element by laminating a layer composed of a different compound that transports the same carrier type as the main carrier type (hole or electron) transported by the doped liquid crystal layer on the liquid crystal layer. Can be produced stably. This layer acts as a protective layer for dopant diffusion. In the absence of such a protective layer, the electron-accepting compound doped in the hole-transporting liquid crystal layer diffuses into the electron-transporting compound to form a new electron level, thereby causing electron transfer and the like. Light emission and the like will be hindered. The above problem can be avoided by laminating the same kind carrier transport layer in contact with the doping liquid crystal layer.

As is well known, a device using a Si crystal requires strict crystal growth to form a Si crystal layer, which is expensive in view of the production process, and a device with a large area is more expensive. It becomes difficult. The liquid crystal layer according to the liquid crystal element of the present invention can be formed by co-evaporation using a vacuum evaporation method or application by a spin coating method because the liquid crystal has self-organization and has an alignment order close to that of a crystal. High productivity. Therefore, a high-performance electronic device can be realized at low cost, and a large-area device can be manufactured due to its self-organizing property. Becomes

[0053]

EXAMPLES (Example 1, Comparative Example 1) As a doped liquid crystal composition, a liquid crystal composition obtained by doping 1 mol% of compound 21 (TCNQ) as an electron-accepting dopant into the liquid crystal compound 4 shown above was used. Organic E having the configuration shown in FIG.
An L element (Example 1) was produced. In FIG. 4, reference numeral 7 denotes a hole injection layer, and the same members as those in FIG. 1 are denoted by the same reference numerals.

First, a 1 wt% chloroform solution of the above liquid crystal composition was spin-coated at 1000 rpm for 20 seconds on a glass substrate on which an ITO film having a thickness of 70 μm was formed. With this method, a liquid crystal layer (hole injection layer) having a thickness of 60 nm was formed.

On this substrate, the above-mentioned hole transporting amorphous material αNPD was vacuum-deposited to a thickness of 20 nm, and Alq3 as a light-emitting layer was vacuum-deposited thereon to a thickness of 50 nm. The degree of vacuum was 1.06 × 10 ⁻³ Pa, and deposition was performed by resistance heating at a deposition rate of 0.2 nm / sec. On top of that, an Al / 1.8 wt% Li alloy was formed to a thickness of 10 nm.
Further, an Al metal was deposited thereon to a thickness of 100 nm.
All were deposited at a degree of vacuum of 1.06 × 10 ⁻³ Pa or less.

As Comparative Example 1, a device was produced in exactly the same manner except that the electron-accepting dopant (compound 21) was omitted.

Using the ITO of the obtained organic EL device as the anode, the current values when 10 V was applied were compared as follows. The liquid crystal composition used shows a crystal at 30 ° C. and a liquid crystal phase at 70 ° C.

[0058] There are 30 ℃ 70 ℃ dopant 4mA / cm ² 30mA / cm ² dopant without 0.5mA / cm ² 5mA / cm ²

The liquid crystal compound used in this example was 1 mol
%, The phase transition temperature does not change significantly, and a phase transition from a crystalline phase to a discotic columnar disordered phase is observed at about 65 ° C. in the temperature increasing process. In the liquid crystal phase, molecular orientation is spontaneously performed, and the current density is dramatically improved.

It can be seen that in the device of this example, the current characteristics were improved by the effect of the liquid crystal phase and the alignment as described above and the generation of free carriers by the dopant. In addition, it was confirmed that the emission luminance was increased almost in proportion to this. In addition, good and stable light emission was observed in a current durability test under a nitrogen atmosphere.

(Example 2, Comparative Example 2) I having a thickness of 70 nm
On a glass substrate on which a TO film is formed, a thickness of 50 nm
Was formed in the same manner as in Example 1 by vacuum deposition of αNPD having a thickness of 40 nm. A liquid crystal compound 5 and a compound 11 (TTF) as an electron-donating dopant were formed thereon by co-evaporation. Co-evaporation was performed by setting in advance a condition where the thickness ratio of the dopant to the liquid crystal compound was 1: 200. The thickness of this liquid crystal layer is 2
It was set to 0 nm. In addition, the same AlLi /
An Al electrode was formed, and an organic EL device (Example 2) having a configuration shown in FIG. 1B was manufactured.

As Comparative Example 2, an element having exactly the same structure as that of Example 1 except that no dopant was used was produced.

Using the ITO of the obtained organic EL device as an anode, the current values when applying 10 V at 30 ° C. were as follows. The liquid crystal composition used is supercooled at 30 ° C., but exhibits a smectic liquid crystal phase. With dopant 8 mA / cm ² Without dopant 1.5 mA / cm ²

As described above, the device of Example 2 having the liquid crystal layer into which the dopant was mixed showed better current characteristics than the device of Comparative Example 2.

Example 3 and Comparative Example 3 Example 2 and Comparative Example 2 except that the liquid crystal compound 5 was changed to the liquid crystal compound 10.
The organic EL devices of Example 3 and Comparative Example 3 were produced in exactly the same manner as in Example 1.

Using the ITO of the obtained organic EL device as an anode, the current values when applying 10 V at 30 ° C. were as follows. The liquid crystal composition used is supercooled at 30 ° C., but exhibits a liquid crystal phase. With dopant 11 mA / cm ² Without dopant ² mA / cm ²

As described above, the device of Example 3 having the liquid crystal layer into which the dopant was mixed exhibited better current characteristics than the device of Comparative Example 3.

Example 4 and Comparative Example 4 Example 2 and Comparative Example 2 except that the liquid crystal compound 5 was changed to the liquid crystal compound 11.
The organic EL devices of Example 4 and Comparative Example 4 were produced in exactly the same manner as in Example 1.

Using the ITO of the obtained organic EL device as an anode and comparing the current value when applying 10 V at 30 ° C., the following results were obtained. The liquid crystal composition used is supercooled at 30 ° C., but exhibits a liquid crystal phase. Dopant There 6mA / cm ² dopant without 0.5mA / cm ²

As described above, the device of Example 3 having the liquid crystal layer into which the dopant was mixed exhibited better current characteristics than the device of Comparative Example 3.

Example 5 An experiment was conducted on the purity of the liquid crystal compound 4 as the main component of the liquid crystal composition used in Example 1 and the current characteristics of the organic EL device of Example 1. The method for manufacturing the element was the same as that in Example 1, and in this example and the comparative example, only the purity of the liquid crystal compound used was changed.

The purity of the liquid crystal compound varies depending on the degree of purification of the liquid crystal compound constituting the compound. Purification varied depending on the number of times of column chromatography and recrystallization purification. The purity of the composition was measured by the following HPLC.

HPLC analysis conditions Column: “CrestPak C18S” manufactured by JASCO Corporation
(Reverse phase) Eluent: methanol HPLC purity detection wavelength: 280 nm

Considering the synthesis / production process, it is considered that almost all impurities can be detected by this method. As a result, several samples having different degrees of purification (purity) could be obtained.

In the same manner as in Example 1, the liquid crystal compound 4 having a different purity was added to the compound 21 as an electron-accepting dopant.
Is used as a hole injection layer by mixing 1 mol% of
An organic EL device was manufactured in the same manner as in Example 1. The HPLC purity of the liquid crystal compound 4 used and the current characteristics of the device (70
At 10 ° C.).

[0076] HPLC purity 98.2% by weight of the liquid crystal compound 4 5mA / cm ² 98.8 wt% 7 mA / cm ² 99.2% by weight 30 mA / cm ² 99.5% by weight 26 mA / cm ²

From the results of this example, it is understood that the purity when the dopant is removed from the liquid crystal composition is preferably 99.0% by weight or more in terms of HPLC purity. The liquid crystal compounds used in Examples 1 to 4 all had a purity of 99.5% by weight.
That is all.

Example 6 As a doped liquid crystal composition, a liquid crystal composition obtained by doping the liquid crystal compound 4 shown above with 1 mol% of compound 21 (TCNQ) as an electron accepting dopant was used, as shown in FIG. (Example 6) was produced. In FIG. 5, reference numeral 8 denotes an electron injection layer, and the same members as those in FIGS. 1 and 4 are denoted by the same reference numerals.

First, a 1 wt% chloroform solution of the above liquid crystal composition was spin-coated at 1000 rpm for 20 seconds on a glass substrate on which an ITO film having a thickness of 70 μm was formed. With this method, a liquid crystal layer (hole injection layer) having a thickness of 60 nm was formed.

On this substrate, αNPD, which is the above-mentioned hole transporting amorphous material, was vacuum-deposited to a thickness of 20 nm, and further, Alq3 as a light-emitting layer was deposited to a thickness of 50 nm on the substrate. The degree of vacuum was 1.06 × 10 ⁻³ Pa, and deposition was performed by resistance heating at a deposition rate of 0.2 nm / sec.

Next, the above-mentioned liquid crystal compound 5 and compound 11 (TTF) as an electron donating dopant were formed into a film by a co-evaporation method. The condition that the thickness ratio of the dopant liquid crystal compound was 1: 200 was set in advance, and co-evaporation was performed to obtain an electron injection layer. The thickness of this liquid crystal layer was 20 nm.

On top of this, an Al / 1.8% by weight Li alloy was formed to a thickness of 10 nm, and an Al metal was further deposited thereon to a thickness of 10 nm.
Evaporated to 0 nm. All have a degree of vacuum of 1.06 × 10 ⁻³ Pa
It was deposited below.

The obtained device has a configuration in which an electron injection layer 8 is provided as compared with the device obtained in Example 1.
The current characteristics were more excellent than those of the device of the above.

[0084]

According to the liquid crystal device of the present invention, the use of an electron-donating compound or an electron-accepting compound having a .pi. Can generate carriers stably by the interaction with As a result, the obtained liquid crystal layer is efficiently and stably doped, and good electronic current characteristics can be obtained. By using the present invention, an electronic element such as a semiconductor element or a light-emitting element can be formed, and the performance of the element can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of an organic EL element.

FIG. 2 shows a MOS FET using the liquid crystal element of the present invention.
It is a cross section of an element.

FIG. 3 is a schematic cross-sectional view of a diode using the liquid crystal element of the present invention.

FIG. 4 is a schematic sectional view showing one configuration of an organic EL element.

FIG. 5 is a schematic sectional view showing one configuration of an organic EL element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal electrode 2 light-emitting layer 3 hole transport layer 4 transparent electrode 5 transparent substrate 6 electron transport layer 7 hole injection layer 8 electron injection layer 21 gate electrode 22 gate insulating layer 23 organic active layer 24 drain electrode 25 source electrode 31 electrode 32 p-type Semiconductor layer 33 n-type semiconductor layer 34 electrode

Continued on front page (72) Inventor Takao Takiguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takashi Moriyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Kamagaya 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 3K007 AB03 AB05 CB01 DA01 DB03 EB00

Claims (13)

[Claims] 1. A liquid crystal device comprising a plurality of layers disposed between a pair of electrodes, wherein at least one of the plurality of layers contains a compound of two or more components and has an electronic carrier transporting ability. A liquid crystal device comprising a liquid crystal layer using a substance, wherein at least one component is an electron donating compound or an electron accepting compound having a π-electron conjugated structure. 2. The liquid crystal device according to claim 1, wherein at least one component of the compound constituting the liquid crystal composition is a liquid crystal compound which exhibits a liquid crystal phase by itself. 3. The liquid crystal device according to claim 2, wherein the concentration of impurities contained in the liquid crystal compound is 1% by weight or less as measured by high performance liquid chromatography. 4. The liquid crystal device according to claim 1, wherein the liquid crystal layer is formed by co-evaporation of a liquid crystal composition by a vacuum evaporation method. 5. The liquid crystal device according to claim 1, wherein the liquid crystal layer is formed by applying a liquid crystal composition by a spin coating method. 6. The liquid crystal device according to claim 1, wherein the liquid crystal composition has a smectic liquid crystal phase. 7. The liquid crystal device according to claim 1, wherein the liquid crystal composition is a discotic liquid crystal phase. 8. The liquid crystal device according to claim 1, wherein a plurality of said liquid crystal layers are provided.
3. The liquid crystal device according to item 1. 9. A liquid crystal composition containing the electron-donating compound having the π-electron conjugate structure in one liquid crystal layer, and the electron-accepting compound having the π-electron conjugate structure in another liquid crystal layer. The liquid crystal device according to claim 8. The ionization potential of claim 10 wherein the electron-donating compound and I _P ^D, when the ionization potential of the other components of the liquid crystal composition and I _P ^LC, for the electron-donating compound, satisfies the following equation according Item 2. The liquid crystal element according to item 1. I _P ^D -I _P ^LC <-0.3eV 11. The ionization potential of the electron-accepting compound and I _P ^A, when the ionization potential of the other components of the liquid crystal composition and I _P ^LC, the electron-accepting compound, satisfies the following equation according Item 2. The liquid crystal element according to item 1. I _P ^A -I _P ^LC> 0.3eV 12. The liquid crystal device according to claim 1, which functions as an organic electroluminescence device. 13. The liquid crystal element according to claim 1, wherein a carrier transport layer made of a different compound that transports the same carrier species as the main carrier species transported by the liquid crystal layer is provided in contact with the liquid crystal layer.