JP3472096B2 - Optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to an optical recording medium.
You. [0002] 2. Description of the Related Art Conventional magneto-optical recording and photothermal phase change type media
Light for recording at a much higher density than optical discs
As one of the recording media, a photorefractive medium is known.
Have been. This photorefractive medium has a high density
Large data such as images can be recorded.
Changes the refractive index of the recording layer by the following mechanism.
It is a medium that can be transformed. In other words, electromagnetic waves
And spatially separate the charge inside it
The electric field generated by this charge causes the recording material to
Change the refractive index of Therefore, it occurs inside the medium.
The larger the electric field, the greater the
It is possible to obtain a large refractive index change. Such a file
Photorefractive media directly modulate the electromagnetic interference pattern.
Holographic, because it can be recorded as a refractive index grating
It is also expected to be applied to optical memory, optical arithmetic element, etc.
Have been. In recent years, organic polymer compounds have been
The development of photorefractive media using
(For example, Japanese Patent Publication No. 6-55901).
However, when using these media,
It was necessary to provide a pole and apply an electric field from outside (for example,
For example, JP-A-6-175167). This is next
It depends on circumstances. [0004] Photoreflection is used to determine the interference pattern of electromagnetic waves.
When irradiating a live medium, the non-
Balanced carriers are generated in photorefractive media
You. The external electric field E is set so as to be parallel to the electromagnetic wave irradiation surface._ex
Generated when a photorefractive medium is applied
The field E is represented by the following equation (3). E = E₀ [(1 + iE_ex/ E_d ) / $ 1 + iE_ex/ (E_d + E_q )}] (I₁ + I₀ )                                                   (3) E₀ = IE_d / (1 + E_d / E_q ) (4) E_d = (2πD) / (μΛ) (5) E_q = (ENΛ) / (2πε) (6) I₀ Is the spatial average of the illuminating light intensity and I₁ Is the irradiation light intensity
Is the difference between the local maximum value and the local minimum value. Λ is the closest pole
This is the distance (spatial wavelength) between the maximum values. ε is a photoreflection
Is the dielectric constant of the active medium, N is the space charge concentration, and D is
The diffusion coefficient, μ, is the mobility. e is the elementary charge, i is the imaginary number
Is a unit and represents a phase (for example, Pochi Y
eh, Introduction to Photo
refractive Nonlinear Opti
cs, John Wiley & Sons, March 1993
chapter). [0005] Physically, E_d Is the electric field due to charge diffusion
And E_q Are ionized impurities and immobile
It represents the space electric field due to a large electric charge. Usually the diffusion coefficient
Between E and the mobility μ, Einstein's relational expression D
/ Μ = kT / e (k is Boltzmann's constant, T is absolute temperature)
Is assumed to hold, so E_d Depends on the substance
There is no constant. Therefore, to obtain a large electric field E,
E_d E compared to_q Is large enough and E_exIncrease
Needed to be E_d E compared to_q To increase
Is required to increase Λ and N in the above equation (6).
It is necessary. However, when Λ is increased, the interference fringe
Since the density is reduced, the recording density of the recording element
It will be cheaper. On the other hand, the space charge concentration N is increased.
Transfer, due to the scattering of the charge.
There is a disadvantage that the mobility is reduced. It is necessary to form an electric field when an external electric field is applied.
The required time is determined by the charge drift speed.
Therefore, a decrease in the mobility means a decrease in the writing speed. I
Therefore, a reduction in mobility must be avoided as much as possible. An external electric field E_exIs applied,
Movable charges (carriers) move in the direction of the electric field,
E substantially coincides with the direction of the external electric field. Pockels effect
This refractive index modulation is performed in the direction of the electric field.
In order to read out the change in the rate by electromagnetic waves, the direction of the electric field
Must be closer to the direction perpendicular to the electromagnetic wave.
For this reason, it is necessary to devise the shape of the electrode to which the electric field is applied.
Therefore, it could not be manufactured at low cost. In addition, usually
The use is limited because it cannot be used for other optical discs.
I was stuck. [0008] SUMMARY OF THE INVENTION The present invention provides a diffusion coefficient D
And the mobility μ (D / μ) are large, and an external electric field
Recording is possible without applying voltage, and the recording capacity is large.
An object of the present invention is to provide a simple optical recording medium. [0009] [MEANS FOR SOLVING THE PROBLEMS]
In addition, the present invention comprises a charge generation material and a charge transport material,
Irradiates the charge of the opposite sign spatially,
Changes in optical properties due to the internal electric field generated by electric charges
Optical recording medium for recording a pattern of light irradiation,
The charge transport material isIndole, carbazole, oxazo
, Isoxazole, thiazole, imidazole,
Pyrazole, oxadiazole, pyrazoline, thiati
Azoles, triazoles, their derivatives, mainly
Compounds in the chain or side chain; hydrazone compounds, tri
Phenylamines, triphenylmethanes, butadiene
, Stilbenes, anthraquinone diphenoquinone,
These derivatives, compounds having them in the main chain or side chain
Object; C ₆₀ , C ₇₀ , Their derivatives; polyacetylene,
Lipyrrole, polythiophene, polyaniline; polysila
, Polygermane; anthracene, pyrene, phenanthate
Selected from the group consisting of ren, and coronene,ion
The first and the second having a difference in activation potential of 0.3 eV or less.
A second two types of charge transport materials,The first charge transport
The most compounded amount of material,The first and second charge transport
The compounding amount of the material is as follows with respect to the total amount W of the charge transporting material.
Characterized by satisfying the relations of equations (1) and (2)
An optical recording medium is provided. [0010] (P₁/W)≦0.8 (1) (P_Two/W)≦0.5 (2) (Where W is the total weight of the charge transport material and P₁and
P_TwoIs the weight of the first and second charge transport materials, respectively.
is there. ) Hereinafter, the present invention will be described in detail. The inventor
Et al. Have conducted intensive studies and have found that their charge transport properties as a medium
Is large (D / μ) between the diffusion coefficient D and the mobility μ
We see that large internal electric fields can be formed using substances.
The present invention has been accomplished based on this. to this
This will be described in detail below. The present inventors have analyzed the transient photocurrent and found that
A method that allows simultaneous measurement of mobility and diffusion coefficient.
RU (Hirao, Nishizawa, Sugiuchi, Physical Review
wLetters. Vol. 75, no. 9, pp17
87-1790 (1995)). This method uses the following
It is done as follows. That is, first, it is formed into a film
The sample is sandwiched between two electrodes, and a specific
Irradiate with loose light. Here, the specific pulse light is
Pal that produces photocarriers that are absorbed only in the vicinity
Light, for example, a pulse of about 1 nanosecond. So
Experimental value of the transient current flowing during
The diffusion coefficient D, the mobility μ and the
Is obtained. Using this method, a component having a charge transporting ability can be used.
Having a system in which the particles are dispersed in a polymer, and a charge transporting ability,
Molecules with small dipole moment should not have charge transport ability
System with a large dipole moment,
The diffusion coefficient D and the mobility μ were measured. As a result, the dipole
As the moment increases, the diffusion coefficient D and the mobility μ
Ratio (D / μ) was found to be large. Sand
That is, if D / μ becomes large, the diffusion becomes
Electric field E_d Increases, and as a result, an external electric field
It has been found that the application becomes unnecessary. Usually, the Einstein relation D / μ
= KT / e (k is Boltzmann's constant, T is absolute temperature)
D / μ is a constant independent of the material
You. However, in the present invention, the most stable crystalline state
But using charge transport molecules in an amorphous state
And the overlap of wave functions between charge transport molecules is
Small in minutes. Therefore, the energy between the two molecules
There is almost no exchange, and in such a state, the charge is
It is not always possible to move to a stable molecule. But
Thus, in the present invention, Einstein's relational expression is
It is not necessary to be in the "thermal equilibrium state"
No. (For example, R. Richert, L. Poutme
ier, and H .; Bassler, Phys. Re
v. Lett. 63, 547 (1989)). This result
As a result, D / μ depends on the material. Note that D / μ is the Einstein relation.
Is not suggested by simulation
(PM Borsenberge)
r, E. H. Magin, M .; van der Auw
eraer, and F. C. de Schryve
r, Phys. Status Solidi (a), 1
40, 9 (1993)). The present inventors have actually
It was measured and confirmed. Medium constituent molecules
D / μ increases as the dipole moment of
The reason is that the larger the dipole moment is,
This is because the mobility decreases. The dipole moment is
Increasing the dipole moment of molecules with transport properties
By or by a molecule with a dipole moment
Can be increased by mixing (eg,
BA, Sugiuchi, Nishizawa, Journal of Imagin
g Science and Technology,
Vol. 37, no. 3, pp 245-250 (199
3), H. Valerian, E .; Brynda, S .;
Nespurek, and W.C. Schnabel,
J. Appl. Phys. 78, 6071 (199
5)). Either way to increase the dipole moment
Also, the mobility can be reduced. That is, in the present invention, the dipole mode is used.
In order to increase the
Even if the dipole moment is increased, the dipole
May be increased. Furthermore, when the dipole moment increases,
The reasons for the lower mobility are as follows.
It is. In other words, the effect of the electric field created by the dipole moment
The electrostatic potential on each charge transfer molecule
Energy distribution of the charge transport molecule
Spread to a width of about 0.1 eV (for example, A. Dieckm
anna, H .; Bassler, and P.S. M. Bor
senberger, J. et al. Chem. Phys. 99,
8136 (1993)). In contrast, the direction of the external electric field
Potential gain when charge is transferred to
For example, 1 nm hopping with an electric field of 1 MV / m
In this case, the potential gain is only 1 meV. this
Thus, the gain of the electrostatic potential increases in the direction of the external electric field.
Bigger than the potential gain when moving
Transfer of electric charge in the direction of the electric field is energetically
Is not always stable. That is, the charge is
In the direction of
You. As described above, the fluctuation of the electric field causes the energy
Energy distribution in the energy distribution.
When moving, the electric charge is not necessarily in the direction of the external electric field.
Does not move, a phenomenon of a decrease in mobility occurs.
However, the electron micro-moving (hopping) speed
It is noteworthy that is not late. You
In other words, because the charge moves in all directions,
Looking only at the movement in the direction of the external electric field, this movement is relative
(Eg, H. Bassle)
r, Phys. Status Solidi (b) 17
5, 15 (1993)). As a result, the charge is
The diffusion coefficient D, which reflects the spread in all directions, is
Mobility, while the mobility μ is
D / μ is large because
You. As is apparent from equation (3), D / μ is large.
As the internal electric field increases as the intensity increases, no external electric field is required
And therefore the electrodes for applying an external electric field are also
It becomes unnecessary. Electric field E due to normal substance diffusion_d Is at room temperature
(300K) and 0.3 mm under the condition of spatial wavelength Λ = 1 μm.
163 MV / m. On the other hand, it has been studied so far
For photorefractive polymers, externally applied
Field is 10 MV / m or more (for example, WE Moe
rner and Scott M.R. Silence,
Chem. Rev .. 94, pp 127-155 (199
4)). Therefore, from the above equation (3), D / μ is 5 or less.
Above, preferably in the case of 10 or more, the same as the external electric field
An internal electric field can be generated by diffusion. Briefly, in ordinary substances
Is the Einstein relation between mobility and diffusion coefficient
The formula holds when the following two conditions are met:
is there. In other words, the carrier
In a state of equilibrium caused by the transition; and
Diffusion is caused by thermal fluctuations.
In contrast, in the system of the present invention, the carrier is converted to light.
And is in a state of non-equilibrium. And spread
Is caused by electric field fluctuation due to dipole moment
This satisfies Einstein's relation
Not a condition. As a result, a large fraction of the dipole moment
If the child or location exists randomly, increase D / μ.
It is possible to be crisp. In a photorefractive medium, light irradiation
The generated carriers hop between the charge transport materials.
Transport by doing. This transport is a drift in the direction of the electric field
Diffusion coefficient (D) and drift
Drift mobility (μ). And this D / μ
Increases, forms an internal electric field without applying an external electric field
it can. In the optical recording medium of the first invention, the electric charge
In an optical recording medium containing a generating material and a charge transport material,
Charge transport material is composed of at least two specific components
High-density recording without applying an external electric field
Enabled. Charge generation in the optical recording medium of the first invention
Any material that absorbs writing light and generates charge
Can be used. Examples of such materials include
For example, selenium and selenium alloys, CdS, CdSe, A
inorganic photoconductors such as sSe, ZnO, α-Si,
Tarocyanines, metal-free phthalocyanines, and their derivatives
Phthalocyanine dyes / pigments such as conductors, naphthalocyanine
Dyes / pigments, monoazo, disazo, trisazo, etc.
Zo dyes / pigments, perylene dyes and pigments, indigo dyes
Ingredients, quinacridone dyes / pigments, anthraquinone, antoua
Polycyclic quinone dyes and pigments such as
For example, electron acceptance as represented by TTF-TCNQ
Transfer complex composed of a conductive substance and an electron donating substance, as
Rhenium salt, C₆₀, C₇₀Fullerenes represented by
And its derivatives. These charge generating materials can be used alone.
Two or more compounds may be used. Charge generation material
Must be capable of absorbing the writing light and generating a charge.
Very high optical density for writing light
If a charge generation material is used, the charge generation inside the device
The writing light may not reach the material. like this
In order to avoid any inconvenience, the optical density of the element
0^-6To 10 is preferred. Also, if the addition concentration of the charge generating material is too high,
In this case, the writing light does not reach the inside.
It becomes difficult to write. On the other hand, the additive concentration is excessively low.
In such cases, the generated charge density is low and the desired internal electric field
I can't get it. Therefore, the concentration of the charge generating material
Optical density of 10^-6Between 10 and
It is preferable to make adjustments as follows. The amount of the charge generating material to be added
About 0.01% to 20.0% by weight based on the whole medium
It is desired that If less than 0.01% by weight
Has a small charge per unit volume generated by light irradiation,
It is difficult to generate sufficient internal charges, while 20.0 weight
%, The probability of association between the charge generating materials increases,
As the conductivity of the medium increases, a high internal electric field cannot be generated.
May be affected. Further, the electric power used for the optical recording medium of the present invention is
Cargo transport material transports holes or electrons
A machine that transports charge by hopping conduction, for example.
Any functional material can be used. Charge transfer
Materials can be delivered alone or in polymers, or even other polymers.
It may be a copolymer with a mer. For example,
Those listed are mentioned. That is, indole, mosquito
Rubazole, oxazole, isoxazole, thiazo
, Imidazole, pyrazole, oxaasiazo
, Pyrazoline, thithiazole, triazole, etc.
Nitrogen-containing cyclic compounds, or derivatives thereof, or
Compounds in the main chain or side chain, hydrazone compounds,
Liphenylamines, triphenylmethanes, butadie
, Stilbene, anthraquinone diphenoquinone, etc.
Quinone compounds or derivatives thereof, or
Compound having a chain or side chain, C₆₀, C₇₀Etc. Fuller
And its derivatives. Furthermore, polyacetylene
, Polypyrrole, polythiophene, polyaniline, etc.
π-conjugated polymer or oligomer; or polysilane, poly
Σ-conjugated polymers and oligomers such as germane; anthrace
, Pyrene, phenanthrene, and coronene
Ring aromatic compounds and the like. The amount of the charge transporting material to be added is from 20 to
It is desired to be about 95% by weight. Less than 20% by weight
In the case of, it is difficult to obtain a sufficient function.
If the content exceeds 5% by weight, the space charge is hardly retained and optical recording is performed.
It may not function as a medium. In the first invention, the electric power as described above is used.
As a transport material, the difference in ionization potential is 0.3e
At least two materials of V or less are blended. like this
In addition, as a charge transport molecule that becomes a hopping site,
By using two or more types with different Luggy levels,
To further broaden the distribution of density of states at the hopping site
I was able to. The charge transport material used is ionized.
If the difference in tension exceeds 0.3 eV, there are two types of holes
Can no longer move between charge transport materials
The original purpose of increasing the fluctuation of the ping site
To achieve the object of the present invention so that it can not be achieved
Can not. Energy levels of different charge transport materials and permanent
It is unlikely that the dipole moment is equal to the charge transport material.
If two or more are used, they fluctuate around the energy level
The density of states is mixed, and as a result, the state density of the system is
This will increase the distribution width of the degree. Large distribution of density of states
D / μ increases as the size of the hologram recording medium increases
Because it can form a high internal electric field when used as
Will be high. In addition, such an ionization potential
The blending amounts of the two types of charge transport materials having a difference are as follows.
Adjusted to meet. 0.2 <(P₁ /W)≦0.8 (1) 0.2 <(P_Two /W)≦0.5 (2) In the above formula, W is the total weight of the charge transport material, and P₁ and
P_Two Is the weight of the first and second charge transport materials, respectively.
is there. [0032] The first charge transporting material is a charge transporting compound.
This is the material with the highest content, and its content is
When the ratio exceeds 0.8, the distribution of the density of states of the charge transport material becomes wider.
No effect is obtained. In addition, the first charge transport material
Is 0.7 or less with respect to the total weight of the charge transporting material.
Is preferable, and more preferably 0.6 or less.
New Thus, at least two types of specific power
Use transporting materials, of which the largest amount is
High diffraction efficiency by setting the sum to 0.8 or less.
Thus, an optical recording medium capable of realizing a high multiplicity was obtained. In the optical recording medium of the first invention,
Are the first and second charges satisfying the conditions as described above.
If a transport material is contained, add a charge transport material
You may. Capacitors generated from the charge generating material as described above
After being injected into the charge transport material, the rear moves between the charge transport materials.
Move to form an electric field. Therefore, the charge transport material used
Ionization potential and electron affinity of other molecules
And the following relationship is desirable. Sand
That is, when the carrier is a hole, the ion of the charge generating material
Potential I_P (CGM) and charge transport material ions
Potential I_P (CTM) satisfies the following relationship
Is preferred. I_P (CTM) <I_P (CGM) At this time, electrons may not move from the charge generation material.
Required, the electron affinity of the charge generating material χ (CGM)
And the electron affinity of the charge transport material χ (CTM) are
It is preferable to satisfy the relationship. Χ (CTM) <χ (CGM) On the other hand, when the carriers are electrons, the charge generating material
Potentials and Electron Parents of Charge and Charge Transport Materials
It is desired that the harmonies have the following relationship. [0038] I_P (CGM) <I_P (CTM) χ (CGM) <χ (CTM) Furthermore, other molecules such as non-linear optical materials,
It is desirable that there is no interaction with the matrix. The optical recording medium of the first invention is, for example,
Charge generation material and at least two specific types of charge
Mixing with the cargo to obtain a solution and evaporating the solvent
Can be produced. Solvents that can be used here
For example, trichloroethane, toluene, etc.
Can be Alternatively, without using a solvent, for example,
Fine particles are mixed in a heated state and quenched.
Thus, the optical recording medium of the first invention may be manufactured. The optical recording medium of the first invention was prepared from a solution.
When manufacturing, dissolve the nonlinear optical molecules in the solution
When the components such as the charge generation material are not polymers.
Can be further dissolved with a polymer as a matrix
Good. Polymers that can be used include, for example,
Tylene resin, nylon resin, polyester resin, polycarbonate
-Carbonate resin, polyarylate resin, butyral tree
Fat, polystyrene resin and styrene-butadiene copolymer
Coalescing resin and the like. These can be used alone.
Mixtures of more than one species may be used. As a nonlinear optical material, for example, C
₆₀Etc. can be used.
Functions as raw material, charge transport material, or matrix
May also be used. Next,Different from the above first inventionSecond
The optical recording medium of the present invention will be described in detail. Second invention
In optical recording media, the optical properties change with the electric field.
Capacity along with charge generation and transport properties
And a predetermined amount of molecules having a melting point of 450K or more.
High-density recording without applying an external electric field
Enabled. In particular, in the optical recording medium of the second invention,
Contains 40 wt% or more of molecules having a melting point of 450K or more.
As a result, a long recording life can be maintained. That is, in the optical recording medium of the second invention,
Is random due to the relatively large dipole moment.
In an electric field, a pair of positive and negative charges is
Of the charge (carrier) of one sign
By intercalating molecules that can transport only
Causes the diffusion caused by the
It is possible to spatially separate negative charges. On this occasion
Modulates the electronic structure of a substance with a diffuse electric field
The optical characteristics of substances such as extinction coefficient, luminous efficiency, and refractive index
Of the excited state by modulating the
The electric field prolongs the life significantly and the change in this characteristic is read.
Take it. The charge generating ability is determined by the optical recording method of the first invention.
Incorporating a charge generating material as described in the medium
Thereby, it can be applied to the optical recording medium of the second invention.
Wear. As a charge transport material to provide charge transport ability
Can also be used as described above, but the second
In the optical recording medium of the present invention, two or more specific
It is not necessary to constitute the charge transport material in minutes. Charge generation materials and electricity
Basically, the mixing ratio of the cargo transportation material is as described above.
Range. That is, the charge generation material
The amount is 0.01 to 20.0% by weight based on the entire recording medium.
The amount of the charge transport material is preferably
20% to 95% by weight of the entire recording medium
preferable. In addition, the ability to change optical characteristics with an electric field
In order to provide this function, molecules or particles having such a function are arranged.
It should just match. The optical characteristics that change with the electric field are as follows.
Light absorption coefficient or luminescence efficiency of fluorescence and phosphorescence, or
Incident on the material, such as light refractive index, light reflectivity and diffraction efficiency
Energy, wavelength, phase, intensity of
It is a physical property that causes the degree and direction to change. Such optical characteristics change depending on the electric field.
Examples of the material include the following. (1) The absorption coefficient is increased by the Franz-Keldysh effect.
Materials whose reflectivity changes Specifically, Si, Ge, Si_x Ge_(1-x) 4 and a half
Conductors and their eutectics, their mixtures, and GaAs
Group 5 semiconductor materials, Group 2-6 semiconductor materials such as ZnSe,
All semiconductor materials including rucopyrite-based semiconductor materials
Can be (2) Absorption coefficient, reflectivity or luminous effect due to exciton effect
Those whose rates change Specifically, phthalocyanine and its derivatives, fuller
And derivatives thereof, pyrrolopyrrole and derivatives thereof
Conductor, anthracene and its derivatives, azulene and
Derivatives, molecular crystals such as azo compounds, and organic semiconductors
Body material, polyacetylene and its derivatives, polydiacetate
Tylene and its derivatives, polysilane and its derivatives
Body, polyparaphenylene and its derivatives, polyparaffin
Enylene vinylene and its derivatives, polythiophene and
And its derivatives, polyparathienylenevinylene and its derivatives
Derivatives, polypyrrole and its derivatives, polyanily
Conjugated polymers such as butane and its derivatives, and σ conjugate
Low-dimensional materials typified by system polymers are listed. (3) Refractive index due to electro-optic effect such as Pockels effect
What changes Specifically, second-order nonlinear optics such as BaSrO and DAN
Materials. (4) The optical characteristics of the excited state change and are excited by an electric field.
Prolong the life of awake state (4-1) Dipole moment of excited state excited by light
That can be stabilized by an electric field, spirofuran and
Photographs of its derivatives, fulgides and their derivatives
Lomic material (4-2) Dipole moment of excited state excited by heat
Thermochromic, such as those that can be stabilized by an electric field
material These materials, alone or in combination, have a molecular state
Alternatively, it is preferable to mix the particles in the medium
No. Further, in the optical recording medium of the second invention, the electric field
Materials that change optical properties require molecules with charge transport ability.
It may also be used. Mixing of materials whose optical properties change by electric field
The amount combines the other functions of charge generation and charge transport
Whether or not to determine
But can absorb or scatter too much light used for recording.
Formulated to make recording impossible
It is desired to do. The optical recording medium according to the second aspect of the present invention
The generating material, the charge transporting material, and the component having optical characteristics due to the electric field
And dissolved in a solvent such as methylene chloride to obtain a solution,
It can be prepared by evaporating the solvent.
Alternatively, without using a solvent, for example, heating the molecular mixture
The fine particles are mixed in the state and quenched,
May be manufactured. As in the case of the first optical recording medium,
When all components such as charge transport materials are not polymers
May contain a polymer as a matrix.
Examples of the polymer that can be used here include, for example, Amorph
Polyester that is transparent and almost transparent in the visible light region
And PMMA, polystyrene and the like. However, the optical recording medium of the second invention has
Molecules having a point of 450K or more are contained in 40% by weight or more.
Molecules with a melting point of 450K or more are
It may also have other functions such as metal material, trap material, or
Has the function of changing optical characteristics by electric field
Good. It is necessary to keep the information recorded on the medium for a long time
In the second invention, the charge transport material or
Is that the melting point of the matrix material is 450K or more.
Preferred. The medium is at room temperature from 10 ° C. to 30 ° C.
Often used at moderate temperatures. Record in this temperature range
In order to maintain the record, in the second invention, the melting point
Limited to 450K or more. In the optical recording medium according to the second invention,
If the ratio of such molecules is less than 40 wt%, a sufficient effect is obtained.
Can't command. And charge generation material, charge transport
The melting point of all materials whose optical properties change depending on the electric field
It is also possible to use a molecule of 450K or more. The optical recording medium of the present invention as described above
Information is recorded by forming interference fringes by two lights
Is a coherent light source.
Light can be used. To obtain interference fringes, the same light
Although it is preferable to use the source light split,
Return the same two light sources to each other.
Input) etc., it is possible to use different light sources.
You. When recording information, one of the two lights
Adds information and creates a dry spot between this and the other light.
The interference fringes are recorded on the medium. Therefore, the optical path difference between the two lights
Cause interference fringes if the light has a short coherent length.
Does not occur. For this reason, the optical path difference is longer than the optical path difference.
A laser having a laser beam is preferred as a light source. Through
Always use a computer terminal, video editing, or data
Considering application to database memory, etc.,
Since the optical path difference is considered to be about 1 cm or more, use a gas laser.
Laser and semiconductor laser, especially feedback to increase coherence length.
A longer semiconductor laser is preferably used as the light source
You. The information recorded as described above
Can be erased as follows. The first one
The method involves uniformly irradiating the medium with light or applying heat.
To redistribute the trapped charge and make the charge distribution uniform
The second method is to reduce the trapped charges.
This is a method of recombining with charges of the opposite polarity. The first method for making the charge distribution uniform is to use a medium
Method for erasing information recorded in a large area
On the other hand, a second method of erasing charge is locally
Suitable for erasing written records. This place
If the medium has a mechanism to generate charges of opposite polarity
It is necessary, for example, when the generated charge is a carrier
Needs to contain electron generating material and its transport material
There is. The optical recording medium of the present invention has two specific types of
By compounding the transport material, or having a melting point of 4
By mixing a predetermined amount of molecules of 50K or more, D /
μ can be increased.
An internal electric field can be formed without applying an electric field,
Optical recording medium with high diffraction efficiency and excellent storage stability
Is obtained. [0057] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, examples of the present invention and comparative examples
The present invention will be described in more detail by way of examples.
Is not limited to these examples. (Embodiment I) In this embodiment, specific two types of charges are used.
Preparation of optical recording media by blending transport materials and examination of their characteristics
Was. Example I-1 Each component was formulated according to the following formulation.
Is dissolved and dispersed in toluene to prepare a toluene solution
did. [0059]     Nonlinear optical material: carbon cluster C₆₀          0.3% by weight     Charge generation material: 0.1% by weight of indigo dye     Charge transport material: (C-1) 25% by weight                 (C-2) 25% by weight     Matrix: 49.6% by weight of polystyrene Each component used here is represented by the following chemical formula. [0060] Embedded image[0061] Embedded image Wherein R is Cl. [0062] Embedded image [0063] Embedded image [0064] Embedded image In the formula, n is an integer. In this example,
Of the charge transport materials (C-1) and (C-2)
The difference in ionization potential is 0.1 eV. By heating and reducing the pressure of the obtained mixed solution,
The solvent was removed to obtain a dry substance. On the other hand, a quartz substrate
To a temperature of 120 ° C.
And the dry material described above was placed and dissolved. Sa
In addition, pressing another quartz substrate from above
As a result, a sample having a thickness of 150 μm was prepared. The absorption spectrum of this sample was measured.
The sum of the absorption spectra of the individual materials
Was. In addition, as a result of measuring the emission spectrum,
No peak was observed and C₆₀Transfer between molecules and other molecules
No complex formation was confirmed. Next, the performance as an optical recording medium is evaluated.
To the electric field formed in the film formed by light irradiation
Of diffraction efficiency of diffraction grating by change of optical characteristics
Was performed. FIG. 1 schematically shows the apparatus used. As shown in FIG.
As described above, the light emitted from the argon laser 7
First beam (object light) by beam splitter 8
2 and a second beam (reference light) 3. Object light
2 is a mirror 10 and reference light 3 is reflected by a mirror 9 respectively.
After that, the two reflected lights intersect with the lens,
The light passes through the sample 1 arranged at the crossing position. Penetrated
The intensity of the beam is the light arranged in the transmission direction 5 of the object light 2.
It is measured by the detector 6. As shown, the object light 2 and the reference light 3 were tested.
By irradiating the sample 1 so that they intersect, the sample
An interference fringe due to laser light was formed. Useful as an optical recording medium
The object light, the reflected light from the object to be recorded.
Or a transmissive image display device composed of a liquid crystal display device, etc.
The light transmitted through the (pager) is irradiated onto the sample,
The reference light is irradiated so as to intersect and cover the irradiation surface.
Writing was performed by leaving the apparatus as it was for 5 minutes. On this occasion,
The interference fringes generated by the superposition of the object beam 2 and the reference beam 3
Generates an internal electric field, modulating the optical properties,
A diffraction grating is formed. Thereafter, the object light 2 is cut off, and
Reproduction is performed by irradiating only the same reference light 3.
Was. The reference light 3 is diffracted by the medium 1 and the components of the reference light 3
And the reflection direction component 4 of the object light 2 and the transmitted light component of the object light 2
The components are divided into six and six components. As shown in FIG. 1, the object light is transmitted.
In direction 5, an optical power for measuring the intensity of the reproduction beam is used.
-Photodetectors such as CCD for capturing beams and reproduced images
6 is installed and irradiates with this photodetector.
Object light that should not be present, that is, a reproduced image is observed,
Acts as a lee. Here, the intensity of the object light reproduced as the reference light
(I_obj.) And the intensity of the irradiated reference light (I_ref.) And ratio
(I_obj./ I_ref.) Was determined as the diffraction efficiency. Said hand
The diffraction efficiency of the film of the present example, measured in order, is
35.0%. In addition, we read record for approximately eight months
It was possible. (Comparative Example I-1) (C)
Example 1 except that only -1) was added at 50% by weight.
Prepare a mixed solution in the same manner as described above, and use it to
A sample having a thickness of 150 μm was prepared by the same method. The characteristics of the obtained sample were compared with those in Example 1.
As a result of similar evaluation, the photorefractive effect
However, the diffraction efficiency was 10.5%, which was higher than that of Example 1.
It was smaller than that. The record cannot be read in about 3 days
Noh. (Example I-2) Each component was prepared according to the following formulation.
Is dissolved and dispersed in toluene to prepare a toluene solution
did. [0077]     Nonlinear optical materials and charge generation materials:                     Carbon cluster C₆₀          0.3% by weight     Charge transport material: (C-3) 20% by weight                 (C-4) 20% by weight                 (C-5) 20% by weight     Matrix: polystyrene 39.7% by weight The components used here are represented by the following chemical formula. [0078] Embedded image [0079] Embedded image [0080] Embedded image Note that the charge transport compounded in this example was
Of the ionization potential of the materials (C-3) and (C-4)
The difference is 0.005 eV. Heat the resulting mixed solution
The solvent is removed by pressing to give a dry substance, which is
Using the same method as in Example (I-1) described above.
A sample having a thickness of 150 μm was prepared. Next, the performance as an optical recording medium is evaluated.
To the electric field formed in the film formed by light irradiation
The diffraction efficiency of the diffraction grating due to the change in optical characteristics caused by
The measurement was performed in the same manner as in Example (I-1). However, write
Including the helium-neon laser beam as the object beam
Divide into two parts, the reference light and irradiate them on the sample for 30 minutes
It was done by doing. The present embodiment measured according to the above procedure
The diffraction efficiency of the example film was 28.0%. Also record
Is the same as in Example (I-1) for about 8 months of reading.
Was possible. (Comparative Example I-2) (C)
-3) except that only 60% by weight was added.
A mixed solution was prepared in the same manner as in (I-2), and
A sample having a thickness of 150 μm was prepared in the same manner as described above.
Was. The characteristics of the obtained sample were evaluated in Example (I-2).
As a result of evaluation in the same way as
Effect was exhibited, but the diffraction efficiency was 3.0%,
It was smaller than the case of (I-2). (Comparative Example I-3) As the charge transporting material,
(C-6) and (C-7) represented by the chemical formulas are respectively
The above examples except that 20% by weight and 40% by weight were added
A mixed solution was prepared in the same manner as in (I-2), and
Then, a sample having a thickness of 150 μm was prepared in the same manner as described above.
Was. [0087] Embedded image Note that the charge transport material (C-
The difference in ionization potential between 6) and (C-7) is
0.9 eV. The characteristics of the obtained sample were evaluated in Example (I).
-2) As a result of evaluation in the same manner as
Active effect, but the diffraction efficiency is 0.01%
And smaller than the case of Example (I-2). As described above, in the first invention,
Two types of electricity with a difference of ON potential of 0.3 eV or less
High loading without applying an external electric field
High-density recording became possible. Two types of ionization potential
If the difference between the signals exceeds 0.3 eV, the diffraction efficiency is low, and
The extremely low function as a recording medium is shown in Comparative Example (I-
It is clear from the result of 3). (Reference example) (Reference example1) Charge of melting point 570K represented by the following chemical formula (C-8)
A transport material and oxadi represented by the following chemical formula (C-9)
Fine particles of azole derivative and titanyl phthalocyanine
And 2- (N, N-
Dimethylamino) -5-nitroacetanilide (DA
N) at a weight ratio of 45: 15: 3: 37.
A solution was prepared by dispersing and dissolving in styrene. [0090] Embedded imageThe obtained mixed solution was cast on a quartz substrate.
Then, drying and heat molding to prepare a sample with a film thickness of 100 μm
Was. Light irradiation to evaluate the performance as an optical recording medium
Optical characteristics caused by the electric field formed in the film
The diffraction efficiency of the diffraction grating was measured according to the change in the characteristics. As shown in FIG. 2, helium-neon ray
The beam of the laser beam into two parts, the object beam 23 and the reference beam 25.
And irradiate them so that they intersect on the sample 21
Then, a diffraction pattern by a laser beam was formed. The figure
In the example shown, sample 21 comprises two transparent support layers 2
2 sandwiched. When used as an optical recording medium,
Light reflected from an object that records light or a liquid crystal display device
Through the transmissive image display element (pager)
Irradiates the sampled light onto the sample, crosses it and covers the irradiated surface.
Irradiate the reference light to cover it. Leave it for one hour
Writing. At this time, the object light 23 and the reference light 2
Internal electric field is generated by interference fringes generated by superposition with 5
As a result, modulation of the optical properties occurs, forming a diffraction grating in the medium.
It is. Thereafter, the object light 23 is cut off, and
The reproduction is performed by irradiating only the same reference beam 25 as
Done. The reference light 25 is diffracted by the medium, and the reference light 2
5 and a transmitted light component 24 of the object light 23.
Be killed. Therefore, an optical power beam and a reproduced image are captured.
And a light detector such as a CCD for detecting the transmission direction of the object light.
If it is installed in advance in
There should be no object light 23, that is, a reproduced image,
Functions as an optical memory. Here, the intensity of the object light reproduced as the reference light
(I_obj.) And the intensity of the irradiated reference light (I_ref.) And ratio
(I_obj./ I_ref.) Was determined as the diffraction efficiency. Said hand
Books measured according to orderReference exampleThe diffraction efficiency of the film is
It was 5.2%. In addition, samples stored at room temperature for one month
When the reference was irradiated, diffracted light was observed and
It was possible. (Reference example2) A pyrazoline derivative represented by the following chemical formula (C-10)
And a melting point of 692 K represented by the following chemical formula (C-11)
Matrix material and fine particles of titanyl phthalocyanine
And DAN in a weight ratio of 20: 40: 8: 32.
A solution was prepared by dispersing and dissolving in methylene chloride. [0098] Embedded image The obtained mixed solution was cast on a quartz substrate.
Then, drying and heat molding to prepare a sample with a film thickness of 100 μm
Was. Next, in order to evaluate the performance as an optical recording medium,
Due to the electric field formed in the film caused by light irradiation
The diffraction efficiency of the diffraction grating due to the change in the optical characteristics,Reference Example 1
The measurement was performed in the same manner as described above. A book measured according to the above procedurereference
An exampleThe diffraction efficiency of the film was 2.1%. Also at room temperature
When stored for 3 months and irradiated with reference light, the diffracted light
Observed. From this result, the records were stored at room temperature for 3 months.
I knew it was done. (Reference example3) An electrode having a melting point of 570 K represented by the following chemical formula (C-12)
Cargo transportation material, fine particles of titanyl phthalocyanine, DA
N was mixed at a weight ratio of 60: 3: 37. [0102] Embedded image The obtained mixture was molded on a quartz substrate by heating.
Thus, a sample having a thickness of 100 μm was prepared. Next, the optical recording medium
To evaluate the performance of the body,
Changes in optical properties due to the electric field formed in the film
The diffraction efficiency of the diffraction gratingReference Example 1Measure in the same way as
Was. The book measured according to the above procedurereference
An exampleThe diffraction efficiency of the film was 0.6%. The record also
It was readable for about 6 months. (Reference example 4) Oxadiazole derivative represented by the chemical formula (C-9)
A conductor, benzyl N-phenylcarbamete with a melting point of 354K,
Weight ratio of fine particles of titanyl phthalocyanine and DAN
And dissolve in methylene chloride at 15: 45: 3: 37
A solution was prepared. The obtained mixed solution was cast on a quartz substrate.
Then, drying and heat molding to prepare a sample with a film thickness of 100 μm
Was. Next, in order to evaluate the performance as an optical recording medium,
Due to the electric field formed in the film caused by light irradiation
The diffraction efficiency of the diffraction grating due to the change in the optical characteristics,Reference Example 1
The measurement was performed in the same way as
Did not. (Reference Example 5) Pyrazoline derivative represented by the chemical formula (C-10)
And fine particles of o-terphenyl and titanyl phthalocyanine
And Dan in a weight ratio of 15: 45: 3: 37.
Mixed. The obtained mixture was molded on a quartz substrate by heating.
Thus, a sample having a thickness of 100 μm was prepared. Next, the optical recording medium
To evaluate the performance of the body,
Changes in optical properties due to the electric field formed in the film
The diffraction efficiency of the diffraction gratingReference Example 1Measure in the same way as
The record had disappeared three days later. (Reference example 6) A compound having a melting point of 440K represented by the following chemical formula (C-13)
Liphenylamine derivative and titanyl phthalocyanine
Fine particles and DAN in a weight ratio of 60: 3: 37
Mixed. [0109] Embedded image The resulting mixture was molded on a quartz substrate by heating.
Thus, a sample having a thickness of 150 μm was prepared. Next, the optical recording medium
To evaluate the performance of the body,
Changes in optical properties due to the electric field formed in the film
The diffraction efficiency of the diffraction gratingReference Example 1Measure in the same way as
The record had disappeared after two weeks. (Reference Example 7) Charge transport at a melting point of 570 K represented by the chemical formula (C-8)
Material and oxadiazole derivative represented by (C-9)
And fullerene C₆₀And the nonlinear optical material 2-
(N, N-dimethylamino) -5-nitroacetanil
And methyl chloride in a weight ratio of 35: 27: 1: 37.
A solution was prepared by dispersing and dissolving in ren. afterwards,Reference example
1A sample was prepared and evaluated in the same manner as
Had disappeared after three weeks. [0112] [0113] As described above, according to the present invention, the expansion is achieved.
Large ratio (D / μ) between the diffusion coefficient D and the mobility μ
High-density information by light irradiation without applying an electric field.
A recordable optical recording medium is provided. Optical recording medium of the present invention
Does not require electrodes to apply an electric field from outside.
And has many advantages due to its industrial value
Is overwhelming.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an experimental apparatus for obtaining diffraction efficiency in the first invention. FIG. 2 is a schematic diagram showing an experimental device for obtaining diffraction efficiency in the second invention. [Explanation of Signs] 1 ... Sample 2 ... Object light 3 ... Reference light 4 ... Reflection direction of object light 5 ... Transmission direction of object light 6 ... Photodetector 7 ... Coherence light source 8 ... Beam splitters 9 and 10 ... Mirror 21 ... Sample 22 Transparent support layer 23 Object light 24 Reproduction light 25 Reference light

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) 5D029 2K028 2K002

Claims (1)

(57) [Claim 1] It contains a charge generating material and a charge transporting material, and spatially separates charges of different signs by irradiating light, and optically generates an internal electric field generated by the charges. An optical recording medium for recording a pattern of light irradiation by changing characteristics, wherein the charge transport material is indole, carbazole, oxa
Sol, isoxazole, thiazole, imidazo
, Pyrazole, oxadiazole, pyrazoline,
Athiazole, triazole, their derivatives, those
Having a main chain or side chain; a hydrazone compound,
Triphenylamines, triphenylmethanes, butadi
Enes, stilbenes, anthraquinone diphenoquino
, Their derivatives, having them in the main or side chain
Compounds; C ₆₀ , C ₇₀ , and derivatives thereof; polyacetylene
Polypyrrole, polythiophene, polyaniline;
Silane, polygermane; anthracene, pyrene, fer
Selected from the group consisting of nantrene and coronene,
The first in which the difference in ionization potential is 0.3 eV or less
And the second two types of charge transport materials, wherein the amount of the first charge transport material is the largest, and the amount of the first and second charge transport materials is less than the total amount W of the charge transport materials. On the other hand, an optical recording medium which satisfies the relationship of the following mathematical expressions (1) and (2). (P ₁ /W)≦0.8 (1) (P ₂ /W)≦0.5 (2) (where W is the total weight of the charge transport material, and P ₁ and P ₂ are Weight of the first and second charge transport materials.)