JP2000256320A - Photorefractive material composition, compound and polymer used for the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound capable of forming to a polymer having a positive hole transport property and a nonlinear optical property, and useful as a medium for optical recording which makes use of a photorefractive effect, especially for holographic recording. SOLUTION: A new compound of formula I (R1, R2, R3, R4, R5 and R6 is each H or a 1-6C alkyl), for example, a compound of formula II. The compound of formula I is preferably subjected to addition condensation reaction with formaldehyde in the presence of an acidic catalyst, such as benzenesulfonic acid, to form a polymer. The compound of formula I is obtained by reacting 1,4-dioxa-8-azaspiro[4,5]decane with a halogenonitrobenzene, especially preferably fluoronitrobenzene, under a basic condition to form a condensate of the both reactant, then reacting the condensate with triphenylamine in the presence of a thiol compound as a reaction accelerator while introducing hydrogen chloride gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to photorefractive material compositions and to novel compounds and polymers used in the compositions. More specifically, a compound having a triphenylamine group having a hole transporting function and an N- (nitrophenyl) -piperidylidene group having nonlinear optical performance, a polymer obtained by condensing the compound with formaldehyde, The present invention relates to a photorefractive material composition containing a compound or a polymer. The composition according to the present invention is used as a medium for optical recording utilizing the photorefractive effect, particularly as a medium for holographic recording, and as a component of various elements for optical information processing.

[0002]

2. Description of the Related Art A photorefractive effect in which the refractive index pattern of a substance changes in accordance with the intensity pattern of irradiated light is known as lithium niobate (LiNbO ₃ ), barium titanate (BaTiO ₃ ), bismuth silicate (Bi ₁₂ SiO 2).
₂₀ ) is well known for inorganic crystals. However, these inorganic crystals have a trade-off relationship between sensitivity and response speed, and it is difficult to improve both of them, and they also have drawbacks of poor moldability and workability.

To overcome these disadvantages of inorganic crystals, polymer-based photorefractive materials have been proposed. Polymer-based photorefractive materials consist of (1) non-linear optical molecules (non-linear optical moleculs).
e; may be abbreviated as NLO below. ), A charge transport agent (hereinafter sometimes abbreviated as CT) and a charge generating agent (hereinafter sometimes abbreviated as CG) in an inert polymer binder, 2) a doping system in which a group having a nonlinear optical property or a charge transport function is introduced into a polymer by a covalent bond, and a component necessary for a mixture of the polymer and a binder polymer is doped; (3) a nonlinear optical property, a charge transport function and a charge; All components required for the development action are roughly classified into a single system in which the main chain or side chain of the polymer is bonded. For example, a typical single photorefractive material is shown in FIG.
It has the structure shown in (a) (the binder polymer is omitted in the figure). In addition, examples of the doped photorefractive material include those having a structure shown in FIG. 1 (b) or (c).

[0004] Although a system for mixing a necessary component with a binder polymer is easy to produce, the component tends to undergo phase separation and the like. Doped systems exhibit better properties in photorefractive performance than single systems and are generally easier to manufacture than single systems. However, even in a doped system, for example, separation (or phase separation) of a doped component or crystallization, such as sublimation of a doped NLO dye, easily occurs, and lack of stability over time has been pointed out.

In recent years, in order to solve the problems of the doping system, a bifunctional photorefractive material in which a charge transporting group and a nonlinear optically active group are bonded to one molecule has been proposed. For example, Yue Zhang et al.

Embedded image 4- (N, N'-diphenylamino) -β-
Nitrostyrene is said to be useful as a bifunctional photorefractive material (Y. Zhang et al., J. App.
l. Phys., 79 (12), 8920 (1996)). Here, an electron-donating group (amino group) is conjugated with an electron-accepting group (nitro group) to generate an electro-optical response (second-order nonlinear optical response). Causes an electron transport property. Henk J. Bolink et al. Also reported that N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl]-is a photoconductive molecule.
The following formula (V) in which dicyanoethylene is bonded to 4,4'-diamine

[0006]

Embedded image Describes the properties of the bifunctional photorefractive compound represented by (HJ Bolink et al., Chem. Mast
er., 9, 1407 (1997)). However, these bifunctional photorefractive compounds have a problem that high-speed response is not sufficient. Therefore, there is a need for a photorefractive material that can be easily manufactured, has a responsiveness that is practically satisfactory, and has excellent stability over time.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photorefractive material composition having a practically satisfactory response, excellent stability over time, and easy production. Novel compound derivable to a polymer having charge transportability and nonlinear optical properties applicable to a photorefractive material composition excellent in heat resistance, a polymer derived from the compound, and a photorefractive material containing the compound or polymer It is not intended to provide the composition.

[0008]

The bifunctional photorefractive compound represented by the above formulas (IV) and (V) is
It has a molecular structure in which a hole transporting active group and a nonlinear optically active group are bonded in a conjugated state. The present inventors have considered that in such a structure, the hole transporting property and the photoconductivity are lower than the basic properties, and as a result, sufficient photorefractive properties cannot be obtained. For the purpose of synthesizing a novel bifunctional photorefractive compound in which a transport active group and a nonlinear optically active group exist in a non-conjugated state,
As a result of intensive studies, it has been found that a compound having a triphenylamine group having a hole transporting function and an N- (nitrophenyl) -piperidylidene group having nonlinear optical properties and a polymer thereof have excellent properties as a photorefractive material. The present invention has been found, and the present invention has been completed. That is, the present invention provides the following compounds, polymers, and photorefractive material compositions containing them.

(1) Formula (I)

Embedded image (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). (2) R ³ is a p-methyl group, a p-ethyl group or a p-ethyl group;
The compound according to the above 1, wherein the compound represents a propyl group, and R ¹ , R ² , R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom. (3) A polymer obtained by an addition condensation reaction between the compound represented by the formula (I) and formaldehyde under an acid catalyst.

(4) The main structure is represented by the formula (II)

Embedded image Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 4. The polymer according to 3. (5) The main structure is the formula (III)

Embedded image (In the formula, R ^{1 to} R ⁶ have the same meaning as described in the above 4, and n is an integer of 2 or more.) The polymer according to the above 4, which has a repeating unit represented by the following formula: (6) R ³ is p-methyl group, p-ethyl group or p-methyl group.
The polymer according to the above item 4 or 5, wherein the polymer represents a propyl group, and R ¹ , R ² , R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom.

(7) A photorefractive material composition comprising the compound as described in (1) or (2) above. (8) A photorefractive material composition comprising the polymer according to any one of the above items 3 to 6.

[0012]

DETAILED DESCRIPTION OF THE INVENTION (1) Bifunctional photorefractive compound (monomer) The novel compound of the present invention is represented by the following general formula (I):
This is a compound in which an N- (nitrophenyl) -piperidylidene group is bonded to a phenyl group of two molecules of triphenylamine.

Embedded image In the above formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The substitution positions of R ^{1 to} R ⁶ , the 4,4′-piperidylidene group and the nitro group on the benzene ring are not limited.
The above compounds can be synthesized by various routes. For example,
It can be synthesized by the following reaction scheme.

[0013]

Embedded image In the above formula, X represents a halogen atom.

That is, first, 1,4-dioxa-8-azaspiro [4,5] decane and halogenonitrobenzene are reacted under basic conditions to form a condensate of the two (first step). Promoter (promoter)
In the presence of the thiol compound (thiol promoter), hydrogen chloride gas is injected to react with triphenylamine (the phenyl group may be substituted with an alkyl group) to obtain the target compound (second step). As the halogenonitrobenzene in the first step, any of o-, m- and p-substituted products can be used. Preferred is fluoronitrobenzene.

The triphenylamine used in the second step is
It can be obtained by reacting an aromatic secondary amine with a halogenoalkylbenzene under conventional conditions. The halogenoalkylbenzene may be any one having sufficient reactivity with the aromatic secondary amine. For example, tolyl diphenylamine (TDPA) is obtained by reacting diphenylamine with 4-iodotoluene. Also,
Examples of the thiol promoter used in the second step include:
3-mercaptopropionic acid and the like. In the compound of the present invention, the triphenylamine (TPA) moiety contributes to the hole transporting property, and the N-nitrophenylpiperidinyl moiety has nonlinear optical properties. As shown in the above formula, in this compound, triphenylamine (TPA) and the N-nitrophenylpiperidinyl group are linked to TPA having charge transport (CT) properties via a piperidylidene group, and the compound ( It does not have a conjugated structure as in (IV) and (V). Specific examples of the compound represented by the general formula (I), R ³ is p- methyl, p- ethyl or p- propyl (p-n-propyl group, p- isopropyl) represents, R ¹ , R ² , R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom, and particularly, R ³ is a p-methyl group, and R ¹ , R ² , R ⁴ , R ⁵ and R ⁶ are each Compounds representing a hydrogen atom are preferred.

(2) Bifunctional Photorefractive Polymer Since triphenylamines and formaldehyde undergo addition condensation in the presence of an acid catalyst, the above compound can be polymerized by utilizing this reaction. That is, the present invention provides a polymer obtained by an addition condensation reaction of a compound represented by the above formula (I) with formaldehyde under an acid catalyst. The polymer obtained by the addition condensation reaction of the compound represented by the formula (I) with formaldehyde in the presence of an acid catalyst has a main structure represented by the following formula (II).

[0017]

Embedded image

In this polymer compound, N- (nitrophenyl) -piperidylidene and triphenylamine are bonded in a non-conjugated structure, and triphenylamine is incorporated in the main chain. As described above, a main chain type polymer of a bifunctional photorefractive compound in which N- (nitrophenyl) -piperidylidene and a triphenylamine moiety are bonded in a non-conjugated system has not been known so far. Examples of the acid catalyst used for the condensation reaction for polymerizing include benzenesulfonic acid,
Organic sulfonic acids such as p-toluenesulfonic acid, naphthalenesulfonic acid and methanesulfonic acid, and aliphatic carboxylic acids such as acetic acid, formic acid and propionic acid. The reaction solvent may be any solvent that does not react with the reaction raw materials such as formaldehyde. For example, dioxane, tetrahydrofuran, dimethylformamide, acetonitrile, benzonitrile, N-methylpyrrolidone, dimethylsulfoxide, nitromethane, nitroethane, methanol, propanol, and a mixed solvent thereof can be used. As a formaldehyde raw material, it is convenient to use a polymer such as paraformaldehyde or trioxymethylene which is easy to handle. The polymerization reaction is carried out using an inert gas (for example,
In a (nitrogen) atmosphere, it is usually carried out in a temperature range of 100 ° C. or lower. By increasing the degree of polymerization, the response is improved,
In consideration of handling properties, the weight average molecular weight is 500 to 500,
000, more preferably about 2,000 to 100,000.

In the above polymerization reaction, in two triphenylamines linked via a piperidylidene group, the hydrogen atom at the para-position is substituted with a methylene group mainly on the basis of the nitrogen atom of the amino group, and the polymerization proceeds. I do. Therefore, when polymerizing, at least one of (R ¹ , R ² ) and (R ³ , R ⁴ ) is such that the hydrogen atom is in the para position with respect to the nitrogen atom of the amino group on the benzene ring. By using a monomer having a substituent, a polymer linked at the para position can be efficiently obtained. For example, one of (R ¹ , R ² ) and (R ³ , R ⁴ ) is a set of (H, H). When it is desired to produce a chain polymer, the para-position of one benzene ring may be hydrogen and the para-position of the other benzene ring may be blocked with an alkyl group.

Thus, the polymers according to the invention typically have a main structure of the general formula (III)

Embedded image In particular, the following general formula (VI)

[0021]

Embedded image And a chain polymer represented by

(3) Photorefractive material composition The present invention relates to a dispersion comprising the above-mentioned monomer as a compound.
Photorefractive material composition and polymer as described above
Of a single system using as a photorefractive compound
A photorefractive material composition is provided. (a) Dispersed photorefractive material composition Dispersed photorefractive material composition according to the present invention
Is a compound comprising a compound of formula (I) and a charge generator
It is dispersed inside. The charge generating agent is exposed to light
It is a compound that generates electric charge, and its dispersibility in polymer
There is no particular limitation as long as it is good. Such a compound
An example of an object is C ₆₀And C₇₀Fullerenes such as 2, 4,
Trinitrofur such as 7-trinitro-9-fluorenone
Orenone and the like. Base polymer used
Limited as long as the polymer has no absorption in the wavelength range
Not. Examples of such polymers include polystyrene
, Polycarbonate, polymethyl methacrylate, polycarbonate
Ester, polyamide, polyurethane, etc.
You.

The compounding amount of the compound of the formula (I) in the composition is 10% by weight or more. If it is less than 10% by weight, a sufficient effect cannot be obtained. It is preferably at least 20% by weight.
The compounding amount of the charge generating agent is preferably 3% by weight or less. The dispersed photorefractive material composition of the present invention may contain components other than the above basic components. For example, a plasticizer, a charge trapping agent and the like can be mentioned. The type and the amount of the plasticizer are not particularly limited as long as they do not affect the transparency in the used wavelength region. Although the composition of the present invention has a charge trapping function by itself, it is possible to enhance the trapping function by adding a charge trapping agent as needed. In the composition of the present invention, since the charges to be transported are holes, a molecule having an oxidation potential lower than that of the triphenylamine derivative as the hole transporting agent may be added as the trapping agent.
When the trapping agent is added, the amount is 0 to about 10% by weight.
It is. Dispersion of each component in the polymer can be performed by a conventional method.

(B) Single photorefractive composition The single photorefractive material composition according to the present invention comprises a polymer of formulas (II) to (III) and a charge generating agent. FIG. 1D schematically shows the structure.
Although FIG. 1D shows a linear polymer,
As long as the main part has a repeating unit represented by the formula (II), it may have a branched chain. Further, another polymer may be mixed with the photorefractive polymer. As such a polymer, those similar to the above-mentioned base polymer can be used. The charge generating agent is the same as the above-mentioned dispersion system. The amount of each component in the composition is the same as that of the dispersion system except that the amount of the bifunctional photorefractive polymer is set to 20% by weight or more, preferably 50% by weight or more. A charge trapping agent or a plasticizer can be added.

(4) Photorefractive device A photorefractive device can be manufactured by a conventional method using the photorefractive material composition of the present invention. The method and shape are not particularly limited,
The most common method is to apply the above-described material composition or a solution thereof in a suitable solvent on a transparent plate, and further stack the transparent plate via a spacer having a desired thickness, thereby forming a plate-like shape. There is a method for forming an element. A transparent electrode substrate such as ITO can be used as the transparent plate.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are illustrative and do not limit the present invention.

Example 1 Synthesis of Bifunctional Photorefractive Compound

Embedded image

Step 1: Synthesis of CT molecule (tolyldiphenylamine)

Embedded image

In a 500-ml three-necked flask equipped with a mechanical stirrer and a condenser, 20 g (118 mmol) of diphenylamine, 311 g (1430 mmol) of 4-iodotoluene and 36.5 g of anhydrous potassium carbonate were placed.
g (246 mmol), cuprous iodide 30.4 g (160
mmol), 18-crown-6 5.55 g (21 mmol)
l) was added and reacted at 200 ° C. for 24 hours with stirring. After cooling, 200 ml of toluene was added, followed by filtration. After distilling off the solvent and unreacted 4-iodotoluene, column chromatography (SiO ₂ , toluene: hexane = 1: 1).
Purification by 2) and recrystallization from ethanol gave 20 g of tolyldiphenylamine (TDPA) (white powder). Yield 65%.

Step 2: Synthesis of NLO molecule (compound 1)

Embedded image

In a 200 ml three-necked flask, 50 ml of pyridine and 7.0 g of 4-fluoronitrobenzene were added.
(49.7 mmol), 10.68 g (77 mmol) of 1,4-dioxa-8-azaspiro [4,5] decane, and 13.7 g (99.4 mmol) of anhydrous potassium carbonate, and the mixture was stirred for 90 minutes.
Heated at ° C for 24 hours. After cooling, the reaction mixture is
of water, stir, filter the precipitate, and add
Washed twice. Thereafter, the filtrate was dissolved in methylene chloride, dehydrated with magnesium sulfate, and recrystallized with ethanol to obtain 12.5 g of yellow crystals. 95% yield. ¹ H-NMR [CDCl ₃ ; δ (ppm)]: piperidine ring hydrogen: 1.8 (t, 4H), 3.55 (t, 4H), ketone protecting group (dioxolane): 3.95 (s, 4H), aromatic ring: 6.8 (d, 2H), 8.08 (d, 2H).

Step 3: Synthesis of Bifunctional Photorefractive Compound (TDPANA)

[0033]

Embedded image Methylene chloride 6 was added to a 200 ml three-necked flask.
0 ml, TDPA 15.76 g (60.8 mmol), 3-mercaptopropionic acid 1.08 g (10 mmol), and 8.
0 g (30.3 mmol) of compound 1 was added, and hydrogen chloride gas generated by dropping hydrochloric acid into sulfuric acid was injected into the reaction system for 20 minutes. Thereafter, while checking the progress of the reaction by TLC, hydrogen chloride gas was further injected, and the mixture was stirred at room temperature for 4 days. During this time, the color of the solution changed from yellow to deep green to deep red. In addition, TLC (toluene / hexane =
In 2/1), the Rf values of the reactants and products are TD
PA: 0.85, compound 1: 0.05, product: 0.38.

After completion of the reaction, methylene chloride was distilled off under reduced pressure.
Open column (mobile phase: toluene / hexane = 2 /
Purified in 1). After the solvent was distilled off, the product was added to hexane to solidify the product, thereby obtaining 4.9 g of a flesh-colored powder. Further washing with hot ethanol yielded 4.5 g of a pale yellow powder. The yield was 20.6% (about 12 g of unreacted TDPA was recovered). ¹ H-NMR [CDCl ₃ ; δ (ppm)]: benzyl: 2.25 (s, 6H), piperidine ring: 2.47 (t, 4H), 3.5 (t, 4H), aromatic ring (TDPA): 6.9 to 7.2 ( m, 26H), Aromatic ring (NLO): 6.8 (d, 2H) to 8.1 (d, 2H).

Example 2 Synthesis of Photorefractive Polymer (Poly (TDDPANA-FA))

[0036]

Embedded image 0.50 g (0.7 mmmo) of the TDPANA obtained in Example 1.
l), paraformaldehyde 0.021g (0.7mmo
l), the catalyst p-toluenesulfonic acid (p-TsOH)
0.0132 g (0.069 mmol; 5 mol%) was charged into an ampoule tube together with 1.0 ml of a reaction solvent 1,4-dioxane, and the atmosphere was replaced with nitrogen. Then, the tube was sealed and heated at 90 ° C. for 24 hours. After completion of the reaction, the mixture was poured into 200 ml of acetone and stirred, the precipitate was filtered, and the precipitate was purified twice by reprecipitation using chloroform / acetone and dried in vacuo to obtain 0.42 g of a pale yellow powder. . 80.6% yield. Molecular weight: Mn = 1.06 × 10 ⁴ , Mw = 2.46 × 10 ⁴ (Mw
/Mn=2.32).

The obtained polymer is soluble in THF, chloroform, chlorobenzene, etc., has a glass transition temperature of 204.4 ° C. measured by GPC,
No thermal decomposition was observed in the measurement temperature range of 50 ° C. Further, when the structure of the polymer was analyzed by ¹ H-NMR and ¹³ C-NMR, a methylene group was mainly bonded to the para position of TDPANA to form a polymer, and a methylene signal due to the meta position was also observed. Was. According to the result of UV measurement, the compound has ultraviolet absorption at around 310 nm and 390 nm, and thus it is considered that the reaction proceeds while the electronic state of TDPANA is maintained.

Example 3 Production of Photorefractive Material Composition and Photorefractive Element Using the Same (1) Production of Photorefractive Material Composition TD obtained in Example 1 as a photorefractive compound
Using PANA, this is converted to tricresyl phosphate (TCP;
Plasticizer), with C ₆₀ was dispersed in polystyrene (base polymer) was prepared dispersion photorefractive material compositions A and B of the following composition (weight ratio). Also,
Poly obtained in Example 2 (TDPANA-FA), and produce a single-based photorefractive material composition C having the following composition tricresyl phosphate (TCP) and C _60. (a) Composition A: TDPANA / PSt / TCP / C ₆₀ =
40 / 29.8 / 30 / 0.2 (b) Composition B: TDPANA / PSt / TCP / C ₆₀ =
20 / 49.8 / 30 / 0.2 (c) Composition C: poly (TDDPANA-FA) / TCP /
C ₆₀ = 59.8 / 40 / 0.2

(2) Production of Photorefractive Element The above-mentioned material composition was dissolved in chlorobenzene (concentration: 0.1 g / ml), and then filtered through a 0.5 μm filter to obtain a sample solution. Next, the sample solution is dropped and cast on an ITO substrate, dried at room temperature for 24 hours, and further dried at 60 ° C for 24 hours.
After drying for an hour, the solvent was completely removed. Then, it was heated on a hot stage, and when the polymer was softened,
The two substrates were stuck together via a 00 μm Teflon spacer, placed on a weight, and allowed to stand at room temperature for 12 hours. Samples A, B and C (corresponding to compositions A, B and C, respectively) having a thickness of 100 μm were obtained by this method. The extinction coefficient (absorbance conversion value at a sample thickness of 1 cm) at 633 nm of the manufactured photorefractive element was measured, and was 4.2 (Sample A), 2.7 (Sample B), and 11.9, respectively.
(Sample C), each showing excellent optical transparency. In these photorefractive devices, no crystallization of components and no phase separation were observed.

Example 4 Evaluation of Characteristics of Photorefractive Element The characteristics of the photorefractive element were evaluated by the following method. (1) Coupling gain coefficient One of the characteristic values of the photorefractive element is a coupling gain coefficient by two-wave coupling. That is, when the photorefractive element is irradiated with two light beams,
A periodic structure (interference fringes) having a light intensity distribution is formed in the medium. However, when an external electric field is applied here, carriers drift, so that a periodic structure having a refractive index having a phase difference from the light intensity distribution (refractive index). Grid) is formed. As a result, a phase difference occurs between the straight wave and the diffracted wave of each beam, so that asymmetric energy exchange occurs between the two beams.

The measurement of the coupling gain coefficient was performed by the configuration schematically shown in FIG. A mirror 2 and a beam splitter 3 are provided on the optical path of the He-Ne laser 1 so that the emitted beam (633 nm) can be given an equal intensity (150 mW / c).
m ² ) were split into _two beams A ₁ and A ₂ , and were crossed in the sample 6 using mirrors 4 and 5 and a lens (not shown) provided on the optical path. Specifically, the angle of incidence on the sample of each beam a beam A ₁ 40 °, beam A ₂ to 6
0 ° (intersection angle was 20 °). The sample 7 has the ITO electrodes on its front and back surfaces as described above. When the voltage is applied to the sample 7, the beam A ₂ (pump light) is turned on, and the beam A _{1 is} turned off. The transmitted light intensity of (probe light) is measured. The transmitted light intensity was measured by the photodiodes 7 and 8. The coupling gain coefficient Γ is obtained by the following formula.

[0042]

Γ = (cos θ / d) [ln (γ ₀ β) -ln
(Β + 1−γ ₀ )] β: intensity ratio of incident beam (pump light A ₂ and probe light A ₁ ) γ ₀ = P / P ₀ (P ₀ : intensity of A ₁ transmitted light without pump light, P: a ₁ transmitted light intensity when there is a pumping light) theta: internal incidence angle of the beam a ₁ or beam a ₂ d: thickness of the sample

1.0 × 10 ⁷ V / m (ie, 10 V / μ
m) to about 9 × 10 ⁷ V / m (ie, 90 V / μm)
The experiment was repeated with an applied voltage in the range of and the coupling gain coefficient was determined.

(2) Diffraction Efficiency The diffraction efficiency was measured by a four-wave mixing method (FWM) whose optical system is schematically shown in FIG. He-Ne laser 11
The 633 nm beam emitted from the
After being polarized light (polarized light in a direction parallel to the drawing), the light was split into two beams by a beam splitter 14 (light intensity was 150 m each).
W / cm ² ). One of these beams is reflected by a mirror 15 and then transmitted through a beam splitter 16 and a polarization beam splitter 17 to form a first writing beam 18.
As a sample. The other beam split by the beam splitter 14 was reflected by a mirror 20 and then made incident on a sample 19 as a second writing beam 21.
Here, the first writing beam 18 and the second writing beam 21 were made to enter so as to intersect in the sample 19, and the intersection angle was 20 °. The angles of incidence of the respective beams on the sample 19 were 60 ° for the first writing beam 18 and 40 ° for the second writing beam 21. On the other hand, the beam reflected by the beam splitter 16 is reflected by the mirror 22 and then transmitted through the half-wave plate 23 and the polarizing plate 24 to be s.
-Polarized light (polarized light in a direction perpendicular to the drawing) is reflected by the mirror 25 and is incident on the sample 19 as a read beam 26 (light intensity: 0.9 mW / cm ² ) so as to face the second write beam 21. Was. Here, the diffraction beam 27 emitted in the direction of the first writing beam 18 was reflected by the polarization beam splitter 17 and received by the photodiode 28. (Light intensity of diffraction beam 27 / light intensity of reading beam 26) × 100 when an electric field was applied to sample 19 was calculated as diffraction efficiency (%). The diffraction efficiency (response signal intensity) changed over time as shown in FIG.

(3) Response time The response time is the light intensity (response signal intensity) of the diffracted beam 27 when the second writing beam 21 is turned ON in the measurement of the above (2) and turned OFF after a certain time. ) Was measured (representative measurement results are shown in FIG. 4), and the rising portion of the diffraction efficiency was determined by fitting to the following equation by the least square method.

[0046]

Η (t) = A [1-exp (−t / τ)] + B (where η (t) is diffraction efficiency (signal intensity) and τ is response time)

The coupling gain coefficient measured by the above method,
The results of the diffraction efficiency and the response time are shown in FIG. 5, FIG. 6, and FIG. The response time of the sample elements (samples A and B) of the dispersion system is 0.9 to 5 seconds in the range of the applied voltage of 40 to 90 V / μm (the vertical axis in FIG. 7 represents the response speed, and the vertical axis in FIG. The reciprocal of the value is the response time.) In addition, the higher the concentration of the bifunctional molecule, the faster the response speed. This result is an order of magnitude faster than the conjugated bifunctional material reported by Zhang et al. [4- (N, N'-diphenylamino) -β-nitrostyrene] and has a non-conjugated structure. This shows that the photoconductivity of the TDPANA molecule is larger than that of the conjugated molecule. In the case of a single polymer (Sample C), the applied voltage range is 15 to 100 m.
s fast response time was realized. This value is the highest among polysilane-based organic photorefractive materials reported so far (writing light intensity: 1 W /
40 ms in cm ² ). Note that polysilane-based materials have disadvantages that they are unstable to light and are easily decomposed, and have low mechanical strength. The high-speed response by the polymer material of the present invention is based on TD having a non-conjugated structure in the polymer structure.
This is probably because the main chain type polymer synthesized from the PANA molecule increased the concentration of the TDPANA unit and increased the charge generation efficiency.

[0048]

The compound of the present invention and the polymer obtained therefrom have a non-conjugated relationship between the structural portion exhibiting charge transport properties and the structural portion exhibiting nonlinear optical characteristics. Photorefractive characteristics are exhibited without impairing the characteristics. Therefore, by using the photorefractive material composition containing the compound or polymer of the present invention, it is possible to obtain a practical photorefractive material having high-speed response and being stably usable, and an optical recording material having a high writing speed. It can be applied to high-speed device materials for optical information processing. When a photorefractive material is used for displaying moving images or for processing optical signals, a high response speed is required, and when it is used as an optical recording material, high-speed response is required to increase the transfer speed. For example, in the case of displaying a moving image, a response speed of a video rate, that is, a response speed of 30 milliseconds is required. In the main-chain polymer photorefractive material of the present invention, this level of high-speed response is realized. Therefore, it has high potential in the above fields.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a configuration of a photorefractive material.

FIG. 2 is a schematic diagram showing a configuration of a measurement system of a coupling gain coefficient by a two-wave mixing method.

FIG. 3 is a schematic diagram showing a configuration of a diffraction signal measurement system by a four-wave mixing method.

FIG. 4 is a graph showing a temporal change pattern of a diffraction signal.

FIG. 5 is a graph showing a coupling gain characteristic (applied voltage-coupling gain) of an element obtained by using the photorefractive material of the present invention.

FIG. 6 is a graph showing diffraction efficiency characteristics (applied voltage-diffraction efficiency coefficient) of an element obtained by using the photorefractive material of the present invention.

FIG. 7 is a graph showing a response speed (applied voltage-response speed) of an element obtained using the photorefractive material of the present invention.

[Explanation of symbols]

 Reference Signs List 1 laser light source, 2, 4, 5 mirror, 3 beam splitter, 6 sample, 7, 8 photodiode, 11 laser light source, 12, 24 polarizing plate, 14, 16 beam splitter, 15, 20, 22, 25 mirror, 17 Polarizing beam splitter, 18 first writing beam, 19 sample, 21 second writing beam, 23 1/2 wave plate, 26 reading beam, 27 diffraction beam, 28 photodiode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Park Shodan 2-24-16 Nakamachi, Koganei-shi, Tokyo Tokyo University of Agriculture and Technology F-term (reference) 2K002 AA01 BA01 CA06 GA10 HA16 4C054 AA02 CC03 DD01 EE01 FF16 4J033 GA01 GA02 HB10

Claims (8)

[Claims] 1. A compound of the formula (I) (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). Wherein R ³ is p- methyl group, represents a p- ethyl or p- propyl, R ^1, R ^2, R ^4, R ⁵ and R
The compound according to claim 1, wherein each ⁶ represents a hydrogen atom. 3. A polymer obtained by an addition condensation reaction of a compound represented by the formula (I) according to claim 1 with formaldehyde in the presence of an acid catalyst. 4. A compound having a main structure of the formula (II): Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Item 7. The polymer according to Item 3. (5) the main structure is represented by the formula (III): (Wherein, R ^{1 to} R ⁶ have the same meaning as described in claim 4, and n is an integer of 2 or more). 6. R ³ represents a p-methyl group, a p-ethyl group or a p-propyl group, and R ¹ , R ² , R ⁴ , R ⁵ and R
^6. The polymer according to claim 4, wherein ⁶ represents a hydrogen atom. 7. A photorefractive material composition comprising the compound according to claim 1 or 2. 8. A photorefractive material composition comprising the polymer according to claim 3. Description: