JP5534506B2 - Low threshold organic reverse supersaturated absorbent material - Google Patents

Description

The present invention relates to an organic reverse supersaturated absorber in which the transmittance of a material decreases in response to steady light. More specifically, the present invention relates to a low-threshold organic reverse supersaturated absorber that responds to weak steady light of about several mW / cm ² .

The reverse supersaturated absorption phenomenon (also referred to as light limiting effect) is a phenomenon in which the absorbance of a material increases with an increase in light intensity. The principle is a phenomenon observed when the excitons of a material are accumulated during light irradiation and the extinction coefficient of the accumulated excitons is larger than that of the original ground state. Applications of the principle include mainly optical switches, light limiting elements, dimming elements, security materials, and the like. This phenomenon occurs instantaneously only in light irradiation with strong instantaneous intensity such as a YAG laser or a femtosecond laser having a high instantaneous intensity in a normal temperature atmosphere in an organic substance, and is several mW / cm of 1 W / cm ² or less. It was not observed in weak steady light such as about ² .

Also in inorganic compounds, materials exhibiting reverse supersaturation absorption characteristics include semiconductors such as CdS, CdSe, CdS _x Se _1-x , Mn ₃ O ₄ , Fe ₂ O ₃ , Co ₃ O ₄ and CuO, TiO ₂ , RuO ₂ , A material composed of a metal oxide such as Sb ₂ O ₃ , Ta ₂ O ₅ , Re ₂ O ₇ , OsO _2, or IrO ₂ and a material in which semiconductor fine particles are dispersed and contained in a transparent substance have been mainly researched and developed ( Non-Patent Document 1 and Patent Document 1). However, in the case of a polycrystalline medium composed of a crystalline semiconductor and a metal oxide or a medium in which semiconductor fine particles are dispersed in glass, light scattering occurs remarkably and the light transmittance is hindered. It is done. Moreover, in a single crystal, a large single crystal cannot be obtained, and it is difficult to increase the area of the element. For this reason, the cost is increased and it is difficult to apply to a large area. Also, the threshold value of the reverse supersaturated absorption characteristic itself requires a very high light intensity of the order of kW / cm ² or more.

In addition, some organic compounds exhibit reverse supersaturated absorption. Non-Patent Documents 2 and 3 show phthalocyanine derivatives as organic material systems that best exhibit reverse supersaturation absorption in YAG lasers as reported so far. Non-Patent Document 4 discloses a platinum complex as a compound that similarly exhibits a reverse supersaturated absorption phenomenon. However, the threshold value of incident light for the reverse supersaturation absorption phenomenon of such a material is about 10 ⁻² J / cm ² in a nanosecond pulse YAG laser, and the same phenomenon is caused by stationary light. Requires a high power of the order of kW / cm ² or higher, and a strength of the order of kW / cm ² is required to produce a large change in transmittance. For this reason, in the conventional organic material system as described above, the reverse supersaturation absorption phenomenon is caused in the case of steady light irradiation or light irradiation with instantaneously large light intensity such as a steady light laser. It does not occur at all.

In order to achieve low threshold reverse supersaturated absorption, two conditions are required: (i) the excited state lifetime is long in the atmosphere at room temperature, and (ii) the absorbance of the transient absorption is sufficiently larger than the absorbance of the ground state. It is necessary to achieve both at the same time. Until now, in the material systems such as Non-Patent Documents 2, 3 and 4, although the condition (ii) has been achieved, since the excited state lifetime is as short as microseconds, the threshold of the material exhibiting reverse supersaturated absorption characteristics Required a high power light of 1 kW / cm ² or more in principle. Even if such a strong steady light is irradiated to develop the reverse saturation absorption function, there is a problem that the organic material is instantly photodegraded, and such an organic material is formed in a large area. However, even when a reverse supersaturated absorption medium is produced, a phenomenon occurs only momentarily with spot light such as a YAG laser, so that the function of a large area cannot be effectively used. Furthermore, since a large light source such as a YAG laser is required, it cannot be used for applications that require miniaturization. For this reason, materials such as LEDs and semiconductor lasers that exhibit large reverse supersaturation absorption characteristics and allow a large area of the medium when irradiated with light of a low power of 1 W / cm ² or less and several mW / cm ² order. Development was desired.

As an organic material having a long excited state lifetime in a room temperature atmosphere, Patent Document 2 discloses that an excited state lifetime in the order of several seconds can be obtained in a room temperature atmosphere by adding a small amount of donor-substituted aromatic hydrocarbon to a disordered steroid medium. It is described that it is achieved. However, Patent Document 2 has no description regarding reverse supersaturated absorption characteristics of light. In addition, a material with a small amount of donor-substituted aromatic hydrocarbon added to a disordered steroid medium has a long excited state lifetime at room temperature in the atmosphere, but the absorbance of transient absorption is not sufficiently larger than the absorbance of the ground state. The increase in absorbance when the light intensity is increased is slight.

Patent Document 2 describes a material in which a steroid medium that forms a disordered state at room temperature is doped with two types of organometallic complex and aromatic compound, and this material efficiently stores and emits light in the room temperature atmosphere. It is stated that it will be achieved. However, there is no description or suggestion regarding reverse supersaturated absorption characteristics of light. Further, in the material design disclosed in Patent Document 2, since the absorbance of transient absorption is not sufficiently larger than the absorbance in the ground state, the increase in absorbance when the light intensity is increased is slight.

JP 2003-248254 A International Publication No. 2009/069790 Pamphlet

Masanori Ando, “Chemistry and Industry”, The Chemical Society of Japan, 1997, Vol. 50, No. 4, p. 621 Joseph. W. Perry, 5 others, Opt. Lett. , 1994, vol. 19, pp. 625 Joseph. W. Perry, 11 others, Science, 1996, vol. 273, pp. 1533 Guijiang Zhou, 4 others, Adv. Funct. Mater. , 2009, vol. 19, pp. 531

The present invention has been made in view of the above-described problems of the prior art, and is weak steady light such as LED, semiconductor laser, sunlight, and the like of 1 W / cm ² or less and several mW / cm ² order in a normal temperature atmosphere. Accordingly, an object of the present invention is to provide a material capable of forming a medium having a large area and a low threshold organic supersaturated absorbing material.

As a result of intensive research to achieve the above object, the present inventors have formed a disordered state at room temperature, and in the matrix having a small diffusion coefficient, two kinds of photosensitizer and dye having predetermined properties are added. In the material to be doped, according to the following invention, the transmittance (linear transmittance) at a light intensity of 1 μW / cm ² or less at an arbitrary wavelength in a normal temperature atmosphere is 10% or more, preferably 50% or more. However, with steady light irradiation of 1 W / cm ² , an organic material whose transmittance is 90% or less, preferably half or less of the linear transmittance, that is, a low threshold organic reverse supersaturated absorbing material, and a medium using the material Successfully developed and completed the present invention.

That is, the present invention provides the following low-threshold organic reverse supersaturated absorbent material and reverse supersaturated absorbent medium using the material.
1. Light having a diffusion coefficient of less than 10 ^-15 cm ² / s at room temperature, an intersystem crossing efficiency of 50% or more, and a phosphorescence quantum yield of 10% or more at room temperature in a matrix forming a disordered state. A material containing a sensitizer and a long excited state lifetime dye having a lifetime of 0.3 seconds or longer in a 77K rigid medium, wherein the minimum excited triplet energy of the photosensitizer is long. Exceeding the lowest excited triplet energy of the excited state lifetime dye, the extinction coefficient of transient absorption of the excited triplet state of the long excited state lifetime dye is larger than the extinction coefficient of the ground state of the photosensitizer at a wavelength of 400 to 600 nm. In addition, the reverse supersaturation is characterized in that the peak top of the extinction coefficient at the UV-visible region absorption wavelength of the ground state of the long excited state lifetime dye is on the shorter wavelength side than the UV-visible region absorption wavelength band of the photosensitizer Osamu material.
2. 2. The reverse supersaturated absorbent material according to 1 above, wherein the matrix is a condensed polycyclic compound having at least one cyclo ring and one OH group.
3. The fused polycyclic compound, reverse over-saturation absorbing material according to the 2 is a steroidal alcohol.
4). The reverse supersaturated absorbing material according to any one of 1 to 3, wherein the photosensitizer is an organometallic complex.
5. The product (φτ) of the excited triplet state formation quantum yield (φ) and the excited triplet state lifetime (τ) in the long excited state lifetime dye upon irradiation with light of a predetermined wavelength is 0.01 or more. 5. The reverse supersaturated absorbent material as described in 1 to 4 above.
6). The reverse of any one of 1 to 5 above, wherein the long excited state lifetime dye is a dye whose lowest excited triplet state is a ππ ^* transition and does not contain an atom having an atomic number of 9 or more in the molecule. Supersaturated absorbent material.
7). 7. The reverse supersaturated absorbing material according to any one of 1 to 6, wherein the long excited state lifetime dye has an aromatic ring, and the aromatic ring is substituted with deuterium.
8. The reverse supersaturated absorbing material according to any one of 1 to 7 above, wherein the linear transmittance at a light intensity of 8.1 μW / cm ² is 50% or more.
9. The reverse supersaturated absorption material according to any one of 1 to 8 is used.
10. Conversely saturable absorber medium according to the 9 reverse over-saturation absorbing material, characterized in that provided on the substrate.

According to the present invention, weak steady light such as LED, semiconductor laser, sunlight, etc. of 1 W / cm ² or less and several mW / cm ² order in normal temperature air greatly increases the absorbance of the material and decreases the transmittance. A material capable of forming a medium with a large area, that is, a low threshold organic supersaturated absorbing material can be provided. In addition, the organic reverse supersaturated absorbing material of the present invention enables functions such as an optical switch to be manifested by an LED, a semiconductor laser, or a low-power light source, thereby enabling downsizing and thinning of the optical system. Furthermore, the organic reverse supersaturated absorbing material of the present invention enables high transparency and formation of a large area element, which is difficult with inorganic reverse supersaturated absorbing materials.

Here, as a characteristic of the low threshold reverse supersaturated absorbing material, the transmittance (linear transmittance) when the intensity of light irradiation is sufficiently weak at 1 μW / cm ² satisfies 10% or more, preferably 50% or more, and It is defined as a material whose transmittance (saturated transmittance) at a strong light intensity that can be realized with an LED such as 1 W / cm ² or a CW semiconductor laser is reduced to 90% or less, preferably less than half of the linear transmittance. . In the present specification, the reverse saturable absorption characteristics of the threshold (F _I value), the linear transmittance defined as the light irradiation intensity of 10% or less.

In the reverse supersaturated absorbing material defined in 1 above, triplet excitons of long excited state lifetime dyes are efficiently accumulated by excitation triplet energy transfer from the photosensitizer upon irradiation with light having a wavelength of 400 to 600 nm. Since the extinction coefficient of the triplet exciton is sufficiently larger than the extinction coefficient of the ground state of the photosensitizer, it is possible to develop a low threshold and a large reverse supersaturation absorption phenomenon.
In the reverse supersaturated absorbing material specified in 1 above, the UV-visible absorption wavelength in the ground state of the long excited state lifetime dye is on the shorter wavelength side than the UV-visible absorption wavelength of the photosensitizer. Thus, when the excited triplet state of the long excited state lifetime dye is formed by sensitization of the photoexcited triplet by the photosensitizer, the light absorption of the long excited state lifetime dye inhibits the light absorption of the photosensitizer. Therefore, it is possible to efficiently form the excited triplet state of the long excited state lifetime dye. On the other hand, when the long excited state lifetime dye is directly photoexcited, the intersystem crossing efficiency is poor, so that the excited triplet state of the long excited state lifetime dye cannot be formed efficiently. Absorption is an impediment to reverse supersaturated absorption properties produced by the accumulation of excited triplet states of long excited state lifetime dyes.

  In the reverse supersaturated absorbing material defined in 2 and 3 above, due to the small diffusion motion of the matrix in the solid, the large excited triplet energy, the high dispersion characteristics of the dye derived from the amorphous nature, and the low oxygen permeability of the matrix The excited triplet state of the long excited state lifetime dye is stabilized even at room temperature. And when the excited triplet state of the long excited state lifetime dye is formed through the photosensitizer, the exciton is stabilized for a long time, so that even if the intensity of the incident light is weak, the long excited state lifetime dye Triplet excitons are accumulated. Thereby, the reverse supersaturated absorption material defined in the above 2 and 3 can reduce the threshold value of the reverse supersaturated absorption characteristic.

By using a metal complex, the reverse supersaturated absorbing material defined in 4 above can use an MLCT absorption band having a small extinction coefficient for absorption of the photosensitizer. Here, MLCT absorption means absorption based on an electronic transition (Metal to Ligand Charge Transfer (MLCT) transition). In reverse supersaturated absorbing materials, it is important that the absorbance in the excited state is sufficiently larger than the absorbance in the ground state, but the small MLCT extinction coefficient in the ground state of this metal complex is the excitation of the long excited state lifetime dye. It is suitable for increasing the difference between the absorption coefficient of the large transient absorption in the triplet state and producing a large decrease in transmittance in the reverse supersaturated absorbing material.

  The reverse supersaturated absorbing material defined in 5 above has a quantum yield (φ) and excited triplet state lifetime (τ) of formation of an excited triplet state in a long excited state lifetime dye when irradiated with light of a predetermined wavelength. By making the product (φτ) of 1 and larger than the conventional value of 0.01 or more, it is possible to lower the threshold value of the reverse supersaturated absorption characteristic.

Since the reverse supersaturated absorbing material defined in 6 above tends to be deactivated from the excited triplet state of ππ ^* of the long excited state lifetime dye to the ground state, photosensitization from the photosensitizer The triplet excitons of the formed long-excited-state lifetime dye are likely to accumulate, and a low threshold of the reverse supersaturated absorption phenomenon can be achieved.

  In the reverse supersaturated absorbing material defined in 7 above, since the infrared vibration energy of C—H is converted to the infrared vibration energy of CD which is lower than that, in the excited triplet state of the long excited state lifetime dye The heat deactivation rate can be delayed. Therefore, the excited triplet lifetime of the long excited state lifetime dye is increased, the triplet excitons of the long excited state lifetime dye are more likely to accumulate, and a further reduction in the threshold of the reverse supersaturated absorption phenomenon is achieved.

  The reverse supersaturated absorbing material defined in 8 above has a linear transmittance of 50% or more, so that when it is irradiated with weak light, it transmits light without waste, while when it is irradiated with strong light. It is possible to efficiently hide the light.

  In addition, the medium using the reverse supersaturated absorbing material of the present invention defined in 9 and 10 above has the characteristics 1 to 8 at the same time, and the transmittance is greatly reduced by the light intensity of an LED or a semiconductor laser. To do. In addition, the glass transition temperature rises due to the high-density hydrogen bonding of the matrix, and the crystallization speed below the glass transition temperature decreases, so that a stable optical amorphous state is formed even at room temperature. It does not impede the permeability. As described above, the reverse supersaturated absorbing medium using the reverse supersaturated absorbing material of the present invention can be suitably used as an optical switch, an optical limiting element, or a dimming element.

It is a conceptual diagram explaining the factor by which the long triplet exciton of the pigment | dye which has the long excited state lifetime dispersed in the conventional organic matrix is quenched by the influence of a matrix. It is a conceptual diagram explaining that the long triplet exciton of the pigment | dye which has the long excited state lifetime dispersed in the matrix which consists of a sterol type compound is hard to be quenched. In the low threshold value organic reverse supersaturated absorbing material of the present invention, it is a conceptual diagram showing a mechanism of a significant transmittance phenomenon with respect to a strong irradiation intensity of light using an energy state diagram of a photosensitizer and a long excited state lifetime dye. In the low threshold value organic reverse supersaturated absorbing material of the present invention, it is a conceptual diagram illustrating sensitization of excited triplets of a long excited state lifetime dye by light irradiation. It is a conceptual diagram explaining the comparison of the degree of the extinction coefficient of a photosensitizer and a long excited state lifetime pigment | dye in the low threshold value organic reverse supersaturated absorption material of this invention. In the low threshold value organic reverse supersaturated absorbing material of the present invention, it is a conceptual diagram illustrating an increase in absorbance and a decrease in transmittance with an increase in the amount of irradiation light. It is a figure explaining the transmittance | permeability of the low threshold value organic reverse supersaturated absorption material of this invention decreasing according to explanatory drawing of FIG. It is a conceptual diagram which shows the extinction coefficient of the photosensitizer used for an Example and a comparative example, and a long excited state lifetime pigment | dye. It is a figure which shows the phosphorescence spectrum of the photosensitizer used for an Example and a comparative example, and a long excited state lifetime dye. It is a figure explaining the mechanism in which the low threshold organic reverse supersaturation absorption characteristic expresses in the material of Example 1. It is a figure which shows the low threshold value organic reverse supersaturated absorption characteristic in the material of an Example and a comparative example. In the material of Example 4, it is a figure explaining the low threshold-value organic reverse supersaturation absorption characteristic in 445 nm light. In the material of Example 4, it is a figure which shows the change rate of the transmitted light intensity | strength in each wavelength at the time of irradiating light of 445 nm at time 0 second, and the phosphorescence intensity change of a pigment | dye (4). It is a figure explaining the low threshold value organic reverse supersaturation absorption characteristic in the material of Example 1 and Comparative Examples 10, 11 and 14. (A) It is a figure which shows the transmittance | permeability change with respect to the incident light power of 405 nm light. (B) It is a figure which shows the excitation triplet lifetime at room temperature of the pigment | dye (1) and the pigment | dye (15) in a medium. In the material of Example 1, it is a figure which shows the transmittance | permeability change with respect to incident light power at the time of changing the pigment | dye density | concentration of Chemical formula 2. FIG. (A) It is a figure which shows the change of (phi), (tau), and (phi) tau with respect to the light of 405 nm when the pigment density | concentration of Chemical formula 2 is changed. (B) It is a figure which shows the transmittance | permeability change with respect to incident light power at the time of changing the pigment density | concentration in a catalyst. The wavelength of light used for transmittance measurement is 405 nm.

Hereinafter, the best mode for carrying out the present invention will be described.
The low-threshold organic reverse supersaturated absorbing material of the present invention has a diffusion coefficient of less than 10 ⁻¹⁵ cm ² / s at room temperature and an intersystem crossing efficiency of 50% or more in a matrix forming a disordered state. In a material containing a photosensitizer having a phosphorescence quantum yield of 10% or more in a photocatalyst and a long excited state lifetime dye having a excited triplet lifetime of 0.3 seconds or longer in a 77K rigid medium, The lowest excited triplet energy of the sensitizer is greater than the lowest excited triplet energy of the long excited state lifetime dye and is excited longer than the extinction coefficient of the ground state of the photosensitizer at wavelengths of 400 to 600 nm, preferably 400 to 500 nm. large extinction coefficient of transient absorption of the excited triplet state of the state lifetime dyes, and the peak top of the absorption coefficient at ultraviolet and visible region absorption wavelength of the ground state of the long excited state lifetime dyes, photosensitizer It is characterized in that than ultraviolet-visible region absorption band located on the shorter wavelength side.

  Here, the mechanism by which the absorbance of the low-threshold organic reverse supersaturated absorbing material of the present invention is increased by light irradiation with low power and the transmittance of light of that wavelength is decreased will be described with reference to FIGS.

Low threshold reverse supersaturation absorption characteristics at a predetermined wavelength, more specifically, the transmittance (linear transmittance) when the intensity of light irradiation at the predetermined wavelength is sufficiently weak at 1 μW / cm ² , preferably 10% or more, preferably In order to obtain a characteristic that the saturation transmittance is 90% or less, preferably half or less of the linear transmittance at an intensity of light irradiation of 1 W / cm ² that satisfies 50% or more, it is efficient by photoexcitation with a predetermined wavelength. Excitons are often accumulated, and the accumulated excitons must strongly absorb light of that wavelength. There are two conditions necessary for this. First, it is necessary to efficiently form long-lived excitons, which determines the degree of threshold reduction. The degree of threshold reduction is determined by the product of the quantum yield (φ) of formation of the excited triplet state and the excited triplet state lifetime τ (φτ, hereinafter simply referred to as the long excited state lifetime dye when irradiated with light of a predetermined wavelength. It is theoretically determined by φτ). Second, in order to obtain a large reverse supersaturated absorption characteristic, the extinction coefficient σ ₂ of the exciton formed by photoexcitation with a predetermined wavelength needs to be larger than the extinction coefficient σ ₁ of the ground state. That is, σ ₂ / σ ₁ (hereinafter sometimes simply referred to as σ) needs to be large, preferably 2 or more, more preferably 10 or more.

  Many devices, such as optical switches, light limiting elements, and light control elements, are usually used in the atmosphere at room temperature. To reduce the threshold of reverse supersaturation absorption in such an environment, increase the value of φτ. There is a need to. In particular, in organic compounds, it is difficult to use a material having a long excited state lifetime in the atmosphere at room temperature. Therefore, the small value of τ has hindered lowering the threshold value of the reverse supersaturation absorption characteristics.

  When a dye having a long excited triplet lifetime usually at 77 K is dispersed in an amorphous matrix centered on a vinyl polymer, as shown in FIG. Since the molecular diffusion movement is performed, the matrix collides with the dye in about milliseconds at the longest even if the long excited state lifetime dye is excited, and the excitation energy is taken away (Kazuyuki Harie, one other person, Chem. Phys. Lett., 1982, vol. 93, pp. 61). As a result, it is impossible to obtain a long excited state life in the order of seconds in a long excited state lifetime dye room temperature atmosphere, and a low threshold reverse supersaturated absorption characteristic cannot be obtained.

  A polymer matrix composed of only rigid parts such as polyimide, not a polymer that easily moves such as a vinyl polymer, has some electron donor property and acceptor property. Even if a long excited state lifetime dye is dispersed here, the excitation energy or electrons of the dye are deprived or donated. As a result, a long excited state such as the second order cannot be obtained at room temperature (GJ See Kavarnos, “Fundamentals of Photonylated Elevtron Transfer”, VCH Publishers, 1993, or JA Bartrop, JD Coyle, “Principles of Fish”, 78. Therefore, the reverse supersaturation absorption characteristic with a low threshold cannot be obtained. (See FIG. 1 (d)).

  A material consisting only of a rigid part is easy to crystallize and the dye is not uniformly dispersed, and as a result of aggregation of long excited state lifetime dyes excluded by the surrounding crystallization, concentration quenching occurs, and a long time such as second order An excited state cannot be obtained, and a reverse threshold saturation absorption characteristic with a low threshold cannot be obtained (see FIG. 1A). In addition, there are compounds that form a stable amorphous material at room temperature even with some low molecular weight compounds and rigid materials. However, even in this material, the binding force between molecules is weak with van der Waals force, so molecular vibrations cannot be suppressed, and even when excited by dispersing long-lived state dyes, A long excited state cannot be obtained, and a reverse threshold saturation absorption characteristic with a low threshold cannot be obtained.

  Furthermore, a normal matrix stores oxygen in the matrix in the atmosphere, and it is difficult to remove this oxygen. In the presence of oxygen, the exciton of the long excited state lifetime dye is deactivated by the effect of oxygen colliding and taking away the energy of the long excited state lifetime dye (Jacbus Kuijt, et al., Anal. Chem). Acta., 2003, vol.488, pp.135). Normal polymer amorphous matrix can remove oxygen by vacuum degassing while heating above the glass transition temperature (Tg), but oxygen will immediately penetrate into the system if left in the atmosphere again. Since it diffuses, a long excited state long-lived excited state is not achieved in the atmosphere under the influence of oxygen (see FIG. 1C).

  As shown in FIG. 2, a matrix composed of a condensed polycyclic compound having at least one cyclo ring and at least one OH group (hydroxyl group), more preferably a steroidal alcohol, is composed of massive molecules. When a strong binding force acts between molecules so that the molecules cannot rotate, the rotational motion of the molecules becomes weaker than usual. Although such massive molecules are easily crystallized at room temperature, a compound or a mixture of compounds containing a hydroxyl group and a phenol group in the matrix tends to have a slow crystallization rate due to the influence of intermolecular hydrogen bonding. And, when the massive molecules are rapidly cooled from the molten state to Tg or less from the melted state of the matrix, they pass through the temperature region of Tg or more and melting point or less for a short time, but crystallization does not occur in about several seconds, so at room temperature. A stable amorphous can be formed. Below the Tg of this amorphous matrix, the bulk molecules are disordered, but stabilized by a three-dimensional hydrogen-bonding network, making it difficult to crystallize at room temperature, and the matrix only performs stretching movements between minute atoms. Therefore, the rotational movement of the massive molecules is prohibited and the probability of collision with the dye is drastically reduced.

  More preferably, the matrix made of a steroidal alcohol is released from the system by heating to a temperature equal to or higher than the melting point, and then amorphousized in a state where oxygen is not present in the system when rapidly cooled to room temperature. Furthermore, since most of the matrix is derived from a cyclo ring and thus does not contain any donor or acceptor site, the effect of depriving the excitation energy of the dye is weak. When a dye having a long excited triplet lifetime (long excited state lifetime dye) of 77 seconds or longer at 77K is dispersed in this matrix and excited, the long excited state lifetime dye is deactivated by thermal vibration or deactivated by oxygen. Inactivation due to electron transfer to and from the matrix does not occur, and the excited triplet state lifetime of the long excited state lifetime dye is stabilized without being affected by the matrix. Triplet lifetime is achieved in room temperature atmosphere.

  As described above, in the organic material, the short excited state lifetime in the atmosphere at room temperature has hindered the lowering of the threshold value of the reverse supersaturated absorption characteristics. Therefore, it is preferable to use a compound such as a steroidal alcohol that has a low diffusion coefficient, excellent oxygen gas barrier properties, low electron donor properties and acceptor properties, and does not induce concentration quenching of long excited state lifetime dyes in the matrix. Therefore, it becomes an important factor for lowering the threshold value of reverse supersaturated absorption characteristics.

Preferably, in a system in which a long-excited-state lifetime dye is dispersed in a matrix formed of a compound such as a steroidal alcohol that has a diffusion coefficient smaller than 10 ^-15 cm ² / s in normal temperature air and forms a disordered state. In the system to which a photosensitizer is further added, the photosensitizer first absorbs light (see (i) of FIG. 3 and FIG. 4). Here, the ground state long excited state lifetime dye does not absorb light having a wavelength of λ (see FIG. 5). The light absorption by the photosensitizer is the case where the metal complex is used as the photosensitizer, from the ground state level (S ₀ level) to the lowest excited singlet level (S ₁ level) or S _0. In some cases, the level is the lowest excited triplet level (T ₁ level). Even when excited to the S ₁ level, the intersystem crossing efficiency is 50% or more due to the heavy atom effect, so that the T ₁ level of the photosensitizer is efficiently formed (FIG. 3 and FIG. 3). (See (ii) in FIG. 4). Here, when the phosphorescence quantum yield of the photosensitizer is 10% or more, the lowest excited triplet state from the photosensitizer is relatively stabilized, and energy deactivation in the T ₁ state is prevented.

Next, since the T ₁ energy of the long excited state lifetime dye is smaller than the energy of the photosensitizer, if a long excited state lifetime dye is selected, triplet-triplet energy transfer occurs efficiently, and the long excited state efficiently. A triplet exciton of a lifetime dye is formed, and φ increases (see (iii) in FIGS. 3 and 4).

In addition, the long excited state lifetime dye is formed in a matrix having a low oxygen content, which is formed from a compound such as a steroidal alcohol that forms a disordered state in a room temperature atmosphere with a diffusion coefficient smaller than 10 ^-15 cm ² / s. Therefore, the excited triplet lifetime becomes long on the order of seconds (τ increases). Due to the long excited triplet lifetime of the long excited state lifetime dye in the room temperature atmosphere, T ₁ excitons of the long excited state lifetime dye accumulate (see FIG. 6). Accumulation of this long excited state lifetime dye increases depending on the light intensity at the wavelength of incident λ (see FIGS. 6 (1) to (4)). The T ₁ exciton of the formed long excited state lifetime dye has a characteristic of ππ ^* transition because σ _{2 with} respect to the wavelength of λ is as large as 10 ⁴ cm ⁻¹ M ^−1, and is derived from MLCT absorption of the photosensitizer. 10 times larger than the value of 10 ⁵ cm ⁻¹ M ⁻¹ of the extinction coefficient σ ₁ (see FIG. 5). For this reason, light having a wavelength of λ is absorbed more strongly than the photosensitizer (see (iv) and FIG. 5 in FIGS. 3 and 4). As a result, the light transmittance with respect to the wavelength of λ of the medium decreases as the light intensity increases (see FIGS. 5 and 7 (1) to (4)). As a result, when the incident light intensity increases, reverse supersaturated absorption characteristics such that the absorbance of the medium increases and the transmittance decreases.

  In the present invention, the matrix component forming the matrix is preferably a massive molecule in which a plurality of cyclo rings are connected to each other, and does not include a site having relatively high mobility such as a side chain. It is preferably a condensed polycyclic compound having at least one, and a compound having an OH group-containing functional group, preferably a hydroxyl group, a carboxyl group, a phosphoric acid group, or the like in a form directly connected to at least a lump portion is suitable. Steroidal alcohol is more preferred. Here, in other words, a compound composed of a massive molecule in which a plurality of cyclo rings are linked to each other can be said to be a compound having a condensed polycyclic hydrocarbon as a basic skeleton and a substituent bonded thereto.

  As a suitable matrix component used in the matrix of the reverse supersaturated absorbent material of the present invention, a compound containing an alcohol group having a bulky molecular skeleton, such as a steroid skeleton, that is, a steroidal alcohol is preferable. Specifically, cholesterol, stegmasterol, pregnenolone, methylandrostenediol, estradiol benzoate, epiandrostene, stenolone, β-sitosterol, pregnenolone acetate, β-cholesterol, 5,16-pregnadien-3β-ol- 20-one, 5α-pregnene-3β-ol-20-one, 5-pregnene-3β, 17-diol-20-one-21-acetate, 5-pregnene-3β, 17-diol-20-one-17- Acetate, 5 Pregnene-3β, 21-diol-20-one-21-acetate, 5-pregnene-3β, 17-diol diacetate, locogenin, tigogenin, esmiragenin, hecogenin, diosgenin and their derivatives, and mixtures containing them It is done.

Other examples of massive molecules linked to multiple cyclo rings include leukotol, pyriesformoside, estriol, estradiol, estrone, echrin glycol, 14-hydroxydihydromorphine, estrone, hexacosahydrohexacene, ic Selenyl acetate, vertisin, corseveramine, ebayedin, (3aα, 6aα, 9aα, 9bβ) -dodecahydro-1H-phenalene-2α, 5α, 8α-triol, heptacyclo [8.4.0.0 ^2,7 . 0 ^3,5 . 0 ^4,8 . 0 ^9,13 . Such as 0 ^{12, 14]} tetradecane-1,9-diol preferably.

  In the matrix component of the reverse supersaturated absorbent material of the present invention, an appropriate amount of a compound containing two or more hydroxyl groups at least at a rigid site as an amorphous stabilizing compound that stabilizes the optical amorphous state of the steroidal alcohol It may be added. Specifically, 1,1,1-tris (4-hydroxyphenyl) ethane, 1,1′-methylenedi-2-naphthol, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane, 1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,3-bis [2- (4-hydroxyphenyl) -2-propyl] benzene, 1 -Naphthol, 2,2'-biphenol, 2,2-bis (2-hydroxy-5-biphenylyl) propane, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, 2,2-bis ( 3-sec-butyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-isopropylphenyl) propane, , 2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane, 2,3,4-trihydroxydiphenylmethane, 2-naphthol, 4,4 ′-(1 , 3-Dimethylbutylidene) diphenol, 4,4 ′-(2-ethylhexylidene) diphenol, 4,4 ′-(2-hydroxybenzylidene) bis (2,3,6-trimethylphenol), 4 , 4′-biphenol, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylmethane, 4,4′-ethylidene bisphenol, 4,4′-methylenebis (2-methylphenol), 4- (1,1,1, 3,3-tetramethylbutyl) phenol, 4-phenylphenol, 4-tert-butylphenol, 9,9-bis (4-hydro) Cyphenyl) fluorene, α, α′-bis (4-hydroxyphenyl) -1,4-diisopropylbenzene, α, α, α′-tris (4-hydroxyphenyl) -1-ethyl-4-isopropylbenzene, 4- Preferred examples include benzyl hydroxybenzoate, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, methyl 4-hydroxybenzoate, resorcinol, and tetrabromobisphenol A.

  As a compounding quantity of such an amorphous stabilization compound, 3-15 mass% is preferable with respect to the said matrix component. If it is 3 mass% or more, the crystallization speed of the matrix component will not be too high, and the component will not crystallize when rapidly cooled from the melting point of the matrix component to room temperature. On the other hand, if it is 15% by mass or less, the amorphous stabilizer itself does not crystallize and does not phase separate from the matrix component, so that the element after film formation does not become cloudy.

  Moreover, when it is desired to form an amorphous state without introducing an amorphous stabilizer, the steroidal alcohol compound also forms an amorphous state. A compound having at least one hydroxyl group and a phenol group in a directly connected form is preferred. Preferred examples of such a compound include β-estateol and estratriol.

The photosensitizer used for the reverse supersaturated absorbing material of the present invention requires that the intersystem crossing efficiency in the sterol compound is 0.5 or more and the phosphorescence quantum yield at room temperature is 10% or more. The phosphorescence quantum yield is preferably 30% or more, and more preferably 50% or more.
Furthermore, as the photosensitizer, (i) the lowest excited triplet energy is larger than the lowest excited triplet energy of the long excited state lifetime dye, and (ii) the photosensitizer at a wavelength of 400 to 600 nm is used. The absorption coefficient of the transient absorption of the excited triplet state of the long excited state lifetime dye is larger than the extinction coefficient of the ground state, and (iii) the absorption of the UV state in the ground state of the long excited state lifetime dye is It is necessary that the peak top be on the shorter wavelength side than the ultraviolet-visible region absorption wavelength band of the photosensitizer. By adding such a photosensitizer, it is possible to achieve a large reduction in transmittance by light irradiation with low power. And by satisfy | filling the requirements of said (i)-(iii), a photosensitizer forms an excited triplet excited state efficiently, and it carries out excited triplet by efficiently transferring energy from there to a long excited state lifetime dye. The excited triplet excited state of the long excited state lifetime dye having a long term state lifetime can be formed efficiently.

As such a photosensitizer, an organometallic complex is preferably exemplified. More specifically, Platinum (III) [2 (4,6-difluorophenyl) pyridinato-N, C ² )-(acetyl-acetonate). Iridium (III), bis (2- (4,6-difluorphenyl) pyridinato-N, C ² ), Tris (2- (2,4-difluorophenyl) pyridine) iridium (III), Tris (2-phenylpyridine) iridium (III), Iridium (III) tris (2- (4-totyl) pyridinato-N, C 2), Bis (2- (9,9-dihexylfluorenyl) -1-pyridine (Acetylacetonate), etc. iridium (III) may be preferably mentioned. In addition, said specific example is an example and will not be limited to this as long as the said requirements are satisfy | filled.

  The compounding amount of such a photosensitizer is preferably 0.05 to 10% by mass, more preferably 0.05 to 7.5% by mass, and further preferably 0.5 to 5% by mass with respect to the matrix component. . If it is 0.5 mass% or more, sufficient absorption for photosensitization can be obtained, and the threshold value for the decrease in transmittance does not increase. On the other hand, when the amount is 10% by mass or less, the dye is less likely to aggregate and the matrix component is not easily crystallized.

The dye used for the reverse supersaturated absorbing material of the present invention needs to be a long excited state lifetime dye having a lifetime of an excited triplet lifetime of 0.3 seconds or longer in a 77K rigid medium. And this long excitation state lifetime pigment | dye has a correlation of above-described (i)-(iii) between photosensitizers.
Such a long excited state lifetime dye has a quantum yield (φ) of formation of an excited triplet state in the long excited state lifetime dye upon irradiation with light of a predetermined wavelength and an excited triplet state lifetime of the long excited state lifetime dye. The product (φτ) with (τ) is preferably 0.01 or more, and more preferably 0.1 or more. By selecting a material having φτ that is 1000 times larger than the conventional one, it is possible to lower the threshold value of the reverse supersaturated absorption characteristic.
The long excited state lifetime dye is preferably a dye whose triplet lowest excited state is a ππ ^* transition and does not contain a base paper having an atomic number of 9 or more in the molecule. With such a dye, the excited triplet lifetime of the dye is increased when efficiently photosensitized by the phototriplet sensitization from the photosensitizer, resulting in a large reverse supersaturation at lower power. It is preferable because it obtains absorption characteristics and reduces the transmittance.

  Such long excited state lifetime dyes include phenanthrene, chrysene, pyrene, perylene, anthracene, tetracene, pentacene, coronene, benzoepyrene, benzog, h, i perylene, benzoanthracene, benzoc, qchrysene, Hexabenzocoronene, 2-dimethylaminotriphenylene, 2-diphenylaminotriphenylene, 2-diethylaminofluorene, 2-dipropylaminofluorene, 3-amino-2-dimethylfluorene, 2,7-bis (N-phenyl-N- ( 4'-N, N-diphenylamino-biphenyl-4-yl))-9,9-dimethyl-fluorene, 9,9-dimethyl-N, N'-diphenyl-N, N'-di-m-tolylfluorene -2,7-diamine, 2,7-bis [phenyl (mtolyl) amino] -9,9 ' Spirofluorene, N, N, N ′, N′-tetraphenylbenzidine, N, N′-diphenyl-N, N′-di (m-tolyl) -benzidine, 3,3 ′, 5,5′-tetra Methyl-benzidine, 4,4′-bis [di (3,5-xylyl) amino] -4 ″ -phenyltriphenylamine, N, N, N ′, N′-tetrakis (p-tolyl) benzidine, 4 , 4′-bis [N- (1-naphthyl) -N-phenylamino] -4 ″ -phenyltriphenylamine, N-phenyl-2naphthylamine, N, N′-diphenyl-benzidine, (phenanthrene-9- Yl) -phenyl-amine, N-phenyl-N-pyren-3-yl-amine, diethyl-pyren-1-yl-amine and the like are preferable.

By using this long excited state lifetime dye, a long triplet excited state lifetime in the matrix component is achieved, so that excitons are efficiently accumulated by photosensitization from the photosensitizer. . In the present invention, a combination of a photosensitizer and a long excited state lifetime dye is important, and a photosensitizer having an MLCT absorption wavelength band in the transient triplet absorption band of these long excited state lifetime dyes is selected. It is important to do. In a system in which this combination is achieved, the absorption coefficient of the transient absorption of the excited triplet state of the long excited state lifetime dye is larger than the MLCT absorption of the metal complex due to the ππ * transition, so that exciton accumulation occurs. Along with this, the absorbance of the material greatly increases, resulting in a large decrease in transmittance.

The long excited state lifetime dye preferably has an aromatic ring, and the aromatic ring is preferably substituted with deuterium. In the present invention, it is not necessary for all to be substituted with deuterium, but from the viewpoint of increasing the lifetime of the formed excited triplet state and obtaining reverse supersaturated absorption characteristics with light irradiation as low as possible, all of the deuterium is replaced. It is preferably substituted.
As a method of deuterium substitution, for example, after synthesizing a dye skeleton, a catalyst such as Pd / C or Pt / C is used, and a temperature of 200 ° C. or higher in heavy water is used. And a method of synthesizing by processing for several tens of hours. When there is a site that is not sufficiently deuterated due to this, from the raw material stage using a catalyst such as Pd / C or Pt / C at a temperature of 200 ° C. or higher in heavy water, and sometimes in a hydrogen atmosphere for several hours. By treating for several tens of hours, a skeleton of an aromatic compound can be formed by synthesis from a deuterated one.

  The blending amount of such a long excited state lifetime dye is preferably 0.05 to 15% by mass, more preferably 0.1 to 7.5% by mass, and 1 to 5% by mass with respect to the matrix component. Is more preferable. If it is 0.05% by mass or more, the efficiency of excited triplet energy transfer from the photosensitizer is good, and triplet excitons of the dye having a sufficiently long excited state lifetime can be accumulated, and the reverse supersaturated absorption characteristics Can be realized. On the other hand, if it is 15% by mass or less, shortening of the excited triplet state lifetime of the long excited state lifetime dye due to concentration quenching between the long excited state lifetime dyes is suppressed, and excitons of the long excited state lifetime dye are sufficiently accumulated. Therefore, it is possible to reduce the threshold value of the reverse supersaturated absorption characteristic. In addition, since the crystallization of the matrix component is not promoted, a highly transparent medium can be realized.

Next, a medium using the reverse supersaturated absorbent material of the present invention will be described.
The reverse supersaturated absorbing medium of the present invention is formed by using the reverse supersaturated absorbing material of the present invention, and the material can be used alone as a medium, or can be provided on a substrate. Although it depends on the application, it is preferable to use it on a substrate because it is versatile.
As an aspect which provides the reverse supersaturated absorption material of this invention on a base material, the aspect etc. which inject | pour this material between several base materials other than the aspect provided only on a base material are mentioned. As the substrate, for example, paper, synthetic paper, plastic film, glass substrate and the like are preferably mentioned. Moreover, when providing a reverse supersaturated absorption material on a base material, or inject | pouring between base materials, it can hold | maintain using binder resin etc. as needed.

  When the reverse supersaturated absorbent material of the present invention is provided on a substrate, a protective layer can be further provided to impart gas barrier properties, chemical resistance, water resistance, abrasion resistance, light resistance, and the like. As the protective layer, a water-soluble polymer, an aqueous emulsion of a hydrophobic compound, a film formed of a resin and the like are preferably exemplified. In the case where the reverse supersaturated absorbing material is injected between a plurality of substrates formed with a gap in advance, a recording medium can be produced without converting the reverse supersaturated absorbing material into ink.

  Moreover, the reverse supersaturated absorption medium using the reverse supersaturated absorbent material of the present invention can be prepared, for example, by providing the material on a porous film. As a result, the medium can be created without converting the reverse supersaturated absorbing material into ink. Examples of the porous film include, but are not limited to, paper, synthetic paper, and a porous polymer film. Further, as the porous film, a polymer film that does not absorb in the visible light region or a porous film obtained by sintering oxide fine particles that do not absorb in the visible light region can be used. When paper is used as the porous film, it can be bent and an inexpensive medium can be created.

  Moreover, it is also possible to give reverse supersaturated absorption characteristics to various wavelengths by laminating media on which different reverse supersaturated absorbent materials of the present invention are deposited.

  The reverse saturable absorbing medium thus obtained can be applied to optical switches, optical limiting elements, dimming elements, security materials, optical recording media, and window light control.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by this example.

(Effect of overlap difference between absorption wavelength of photosensitizer and wavelength of transient absorption of long excited state dye on reverse supersaturated absorption characteristics)

Example 1
As a photosensitizer, 1.0 part by mass of a metal complex (1) having the structure of the following chemical formula 1 as a photosensitizer, 5.0 parts by mass of a dye (1) having a structure of the following chemical formula 2 as a long excited state lifetime dye, as a matrix 94.0 parts by mass of a sterol compound (1) having the structure of the following chemical formula 3 was blended to obtain a powder sample. Then, the obtained powder sample was once heated to 200 ° C. to melt the matrix, thereby dissolving other compounds in the matrix. Next, this sample was injected between two glass plates with a gap of 100 microns in a liquid state at 200 ° C. by capillary action, and then rapidly cooled to room temperature and made amorphous, so that it was sandwiched between two glass substrates. A reverse supersaturated absorption medium in a fresh state was obtained. This medium was irradiated with 405 nm CW semiconductor laser light (manufactured by B & WTEK) from a low intensity, and the transmittance of the light transmittance of 405 nm transmitted through the medium at each intensity was measured.

Example 2
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (2) having the structure of the following chemical formula 4 was used as the long excited state lifetime dye, and various values were measured.

Example 3
In Example 1, a sample was prepared in the same manner as in Example 1 except that the metal complex (2) having the structure of the following chemical formula 5 was used as a photosensitizer, and various values were measured.

Example 4
In Example 3, a sample was prepared and various values were measured in the same manner as in Example 1 except that the dye (2) having the structure of Chemical Formula 4 was used as the long excited state lifetime dye.

Example 5
In Example 1, except that the metal complex (3) having the structure of the following chemical formula 6 is used as the photosensitizer and the dye (3) having the structure of the following chemical formula 7 is used as the long excited state lifetime dye, Similarly, samples were prepared and various values were measured.

Example 6
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (4) having the structure of the following chemical formula 8 was used as the long excited state lifetime dye, and various values were measured.

Example 7
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (3) having the structure of Chemical Formula 7 was used as the long excited state lifetime dye, and various values were measured.

Example 8
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (5) having the structure of the following chemical formula 9 was used as the long excited state lifetime dye, and various values were measured.

FIG. 8 shows the absorption spectra of the photosensitizer and long excited state lifetime dye contained in the materials described in Examples 1 to 8 and the transient absorption spectrum from the T ₁ level of the long excited state lifetime dye. Indicates. Moreover, in FIG. 9, the phosphorescence spectrum of the photosensitizer and long excited state lifetime pigment | dye contained in the material described in Examples 1-8 is shown.
Of these spectra shown in FIGS. 8 and 9, Example 1 will be described with reference to FIG.
The light at 405 nm is absorbed depending on the small extinction coefficient of MLCT of the photosensitizer of Chemical Formula 1 ((i) in FIG. 10). Because of the small extinction coefficient of MLCT of the photosensitizer of Chemical Formula 1 (abbreviated as Chemical Formula 1; the same applies to other chemical formulas), the linear transmittance of the medium of Example 1 is 1 mm thick. Is as large as 51%. On the other hand, in the wavelength band of 405 nm, there is no absorption of the long excited state lifetime dye of Chemical Formula 2 ((ii) in FIG. 10). After light absorption of the photosensitizer, the T ₁ energy of the long excited state lifetime dye of Formula 2 is 0.5 eV or more smaller than the energy of Formula 1, so that triplet-triplet energy transfer occurs efficiently, and Formula 2 T ₁ state is formed ((iii) of FIG. 10). As shown in Table 1, the phosphorescence quantum yield φ _P of the excited T ₁ state of Formula 1 is 0.13, and the energy transfer efficiency φ _ET to the long excited state lifetime dye is 0.3, so that it is absorbed. and the energy of φ = φ _P φ _ET light 0.039, i.e. 3.9% is used to form the T ₁ state of the chemical formula 2. This T ₁ state of Formula 2 is stabilized in a matrix composed of the steroidal alcohol of Formula 3 and has a long life of 0.46 seconds on average. As a result, since the value of φτ is large, the T ₁ state of Chemical Formula 2 is efficiently accumulated. Since the T ₁ state of the chemical formula 2 has an extinction coefficient approximately 14 times that of the ground state of the chemical formula 1 with respect to the light of 405 nm ((iv) in FIG. 10), the light of 405 nm is absorbed more strongly. As a result, as the light intensity is increased as in the transmittance change of Example 1 in FIG. 11, the absorbance increases, and thus the transmittance decreases.

In the materials described in Examples 1 to 5, the value of φτ is large for light of each wavelength described in Table 1, and the absorption of the photosensitizer efficiently absorbs the long excited state lifetime dye. The T ₁ level is accumulated. As a result, the threshold value (F _I ) of the reverse supersaturated absorption characteristic is reduced to the mW / cm ² level. Further, since the transient absorption of the T ₁ level of the long excited state lifetime dye is larger than the absorption of the ground state of the photosensitizer, σ is as large as 10 or more, and the exciton of the T ₁ state of the long excited state lifetime dye As a result of accumulation, the transmittance is greatly reduced. As a result, irradiation with light intensity of about 1 W / cm ² reduces the transmittance to preferably half or less of the linear transmittance (T _s / T _{l in the} table is 0.5 or less). For example, T _s / T _{l in} Example 1 is 0.33, and the transmittance is 0.33 times the linear transmittance, that is, half or less. As a result, there is a threshold value in a region from several mW to several tens of mW / cm ² , and the linear transmittance is 50% or more, and the transmittance at 1 W / cm ² is less than half of the linear transmittance.

FIG. 12 shows the change in transmittance when the light intensity at 445 nm in Example 4 is changed. In the material of Example 4, as shown in FIG. 13, the change in transmittance at 445 nm changes on the same time scale as the phosphorescent signal of Formula 4. This indicates that this change in transmittance depends on the T ₁ state of Formula 4. In addition, it can be seen from the transient absorption spectrum in the excited triplet of Formula 4 in FIG. 8 that the transmittance change at 543 nm and the transmittance change at 633 nm are smaller than those at 445 nm. From this, the transmittance is reduced by efficiently accumulating the excited triplet state of the long-lived excited dye by light irradiation. Here, ◯, □, Δ, ●, ■, ▲, and ▼ in FIG. 13 correspond to the respective incident light intensities in FIG. 12.

In the case of Examples 6 to 8, the value of φτ is large at the wavelengths shown in Table 1, and T ₁ excitons of the long excited state lifetime dye are efficiently accumulated by light irradiation. Since the transient extinction coefficient σ ₂ of the exciton of the dye is about 2.5 to 5.7 in the wavelength region shown in Table 1 (see FIG. 8), when the irradiation light intensity is increased as shown in FIG. The transmittance decrease is about 0.75 to 0.89. As a result, the linear transmittance is large, but since the decrease in transmittance at 1 W / cm ² is about 0.75 to 0.89, the performance is practically sufficient even if it is not excellent. It can be said.

As described above, in the present invention, the transient absorption of the excited triplet state of the dye having a long excited state lifetime is longer than the extinction coefficient σ ₁ of the ground state of the photosensitizer at a wavelength of 400 to 600 nm, preferably 400 to 500 nm. It can be seen that the requirement of the present invention that the extinction coefficient σ ₂ is large is an important factor for obtaining a low threshold and good reverse supersaturated absorption characteristics.

(Difference in reverse supersaturated absorption characteristics due to differences in matrix)

Example 9
As a photosensitizer, 1.0 part by mass of the metal complex (1) having the structure of Formula 1 as a photosensitizer, and 5.0 parts by mass of a dye (1) having the structure of Formula 2 as a long excited state lifetime dye, as a matrix 85.0 parts by mass of the sterol compound (2) having the structure of the following chemical formula 10 and 9.0 parts by mass of the compound (1) having the structure of the following chemical formula 11 as an amorphous stabilizer are obtained to obtain a powder sample. It was. The obtained powder sample was once heated to 180 ° C. to melt the matrix, thereby dissolving other compounds in the matrix. Then, this sample was injected between two glass plates with a gap of 1 cm in a liquid state at 180 ° C. by capillary action, and then rapidly cooled to room temperature and made amorphous to be sandwiched between two glass substrates. A reverse supersaturated absorbing medium in the state was obtained. This medium was irradiated with 405 nm CW semiconductor laser light (manufactured by B & WTEK) from a low intensity, and the transmittance of the light transmittance of 405 nm transmitted through the medium at each intensity was measured.

Example 10
As a photosensitizer, 1.0 part by mass of the metal complex (1) having the structure of Formula 1 as a photosensitizer, and 5.0 parts by mass of a dye (1) having the structure of Formula 2 as a long excited state lifetime dye, as a matrix 85.0 parts by mass of a sterol compound (3) having the structure of the following chemical formula 12 and 9.0 parts by mass of the compound (1) having the structure of Chemical Formula 11 as an amorphous stabilizer were obtained to obtain a powder sample. . The obtained powder sample was once heated to 230 ° C. to melt the matrix, thereby dissolving other compounds in the matrix. Then, this sample was injected between two glass plates with a gap of 1 cm in a liquid state at 230 ° C. by capillary action, and then rapidly cooled to room temperature and made amorphous, so that it was sandwiched between two glass substrates. A reverse supersaturated absorbing medium in the state was obtained. This medium was irradiated with 405 nm CW semiconductor laser light (manufactured by B & WTEK) from a low intensity, and the transmittance of the light transmittance of 405 nm transmitted through the medium at each intensity was measured.

Comparative Example 1
10.0 parts by mass of the metal complex (1) having the structure of Chemical Formula 1 as a photosensitizer and 5.0 parts by mass of the dye (1) having the structure of Chemical Formula 2 as a long excited state lifetime dye as a matrix 94.0 parts by mass of polymethyl methacrylate (hereinafter referred to as “PMMA”) was dissolved in dichloroethane, and a thin film having a thickness of about 10 μm was formed on a glass substrate by spin coating. This medium was irradiated with 405 nm CW semiconductor laser light (manufactured by B & WTEK) from a low intensity, and the transmittance of the light transmittance of 405 nm transmitted through the medium at each intensity was measured.

Comparative Example 2
Comparative Example 1 and PMMA of Comparative Example 1 except that the polyvinyl chloride-vinyl acetate copolymer (vinyl chloride part: vinyl acetate part = 9: 1 (mass ratio)) (hereinafter referred to as “PVC-PVAc”) Similarly, the materials were adjusted and measured.

Comparative Example 3
The medium of Comparative Example 1 was sealed in a vacuum container equipped with a quartz window capable of transmission measurement, and the measurement was performed under the condition that it was sufficiently deaerated with a vacuum pump.

Comparative Example 4
1.0 part by weight of the metal complex (1) having the structure of the above chemical formula 1 as a photosensitizer, 5.0 parts by weight of the dye (1) having the structure of the above chemical formula 2 as a long excited state lifetime dye, N, N-dimethylformamide (hereinafter referred to as “DMF”) 94.0 parts by mass, this solution was vacuum degassed five times, and then injected into a 1 mm thick quartz cell in a state where it was not released into the atmosphere, A 405 nm CW semiconductor laser beam (manufactured by B & WTEK) was irradiated from a low intensity, and the transmittance of a light transmission of 405 nm that transmitted a 1 mm thick solution at each intensity was measured.

In Comparative Examples 1 and 3, as shown in Table 2, since the excited triplet lifetime (τ) at the T ₁ level of the long excited state lifetime dye of Formula 2 is remarkably short, the light intensity at the level of 1 W / cm ² Then, no decrease in transmittance is observed. This is because, in a normal polymer matrix, oxygen and local diffusion motions quench long excitons. Even in conditions removed oxygen in a high vacuum of as in Comparative Example 3, the quench markedly occurs, thereby increasing the F _I value is a threshold value of the reverse saturable absorption characteristics as a result. The oxygen concentration in the matrix can be measured by comparing the phosphorescence lifetime in vacuum degassing and in the atmosphere. In the normal polymer amorphous matrix of Comparative Examples 1 and 2, 10 ⁻⁵ to 10 ⁻⁴ M Met. In Non-Patent Document 5, the diffusion coefficient of PMMA at room temperature is determined by β relaxation which means rotational movement of the side chain and α` relaxation which means local movement of the main chain, and is 6 × 10 ⁻¹⁴ cm ² / The value s is shown.
In other words, when a matrix having a diffusion coefficient of at least 10 ⁻¹⁵ cm ² / s or more at room temperature is used, it is difficult to obtain a long excited state lifetime of 0.3 seconds or more, so that the target low threshold value is obtained. The reverse supersaturated absorption characteristics cannot be obtained. In a normal polymer matrix having a large electron donor property or acceptor property, the diffusion coefficient at room temperature is as large as 10 ¹⁵ cm ² / s, and thus a long excited state lifetime of 0.3 seconds or more cannot be obtained (J E. Guillet, et al., 2 names, Macromolecules, 1974, vol. 7, No. 2, pp. 233-244). Therefore, it is not possible to obtain a low threshold reverse supersaturated absorption characteristic.

Further, in Comparative Example 4, when the reverse supersaturated absorption characteristic was evaluated in a state where the DMF solvent was a liquid matrix, the reverse supersaturated absorption characteristic was obtained even in an environment where oxygen was removed under vacuum due to the remarkably small τ of Chemical Formula 2. Not observed. This is because the large diffusion coefficient of 10 ⁻⁵ cm ² / s of DMF in the liquid state quenches the triplet exciton of Chemical Formula 2 within 100 microseconds, so that the value of φτ becomes extremely small. This is because excitons of Chemical Formula 2 are not accumulated at all.

On the other hand, since the material obtained in Example 1 has high disorder as described above, the oxygen triplet concentration is low, and the excited triplet state of Formula 2 is stabilized in a matrix of steroidal alcohol having a small diffusion coefficient. A low threshold reverse supersaturated absorption characteristic is observed. The diffusion coefficient of the matrix at room temperature in Example 1 could not be measured by the method of analyzing by phosphorescence lifetime multidecay described in Non-Patent Document 2. This is because the material obtained in Example 1 at room temperature does not show any multi-decay of phosphorescence lifetime at room temperature. It can be said that the value is at least smaller than that of PMMA. The oxygen concentration was obtained by measuring the length of the excited triplet lifetime in the atmosphere and in a high vacuum, and was 10 ⁻¹² to 10 ⁻¹¹ M.

Further, not only in the matrix composed of the steroidal alcohol of the chemical formula 3 described in Example 1, but also in the matrix composed of other steroidal alcohols such as the chemical formula 10 and the chemical formula 12 as in Examples 9 and 10, good low Threshold reverse supersaturated absorption characteristics are observed in the room temperature atmosphere. The diffusion coefficient cannot be measured by the technique described in Non-Patent Document 2 because multi-decay of phosphorescence lifetime is not observed, and is at least sufficiently smaller than 6 × 10 ⁻¹⁴ cm ² / s at room temperature of PMMA. it can. The oxygen concentration is obtained by measuring the length of the excited triplet life under high vacuum and the atmosphere was 10 ^-1 ~10 ⁰ M. Here, the chemical formula 11 which is a phenol derivative is added for the purpose of increasing the hydrogen bond density to reduce the diffusion coefficient and increasing the disorder of the matrix.

As described above, in the material of the present invention, it is possible to use at least one steroidal alcohol as a matrix for forming a disordered state having a diffusion coefficient smaller than 10 ⁻¹⁵ cm ² / s, and a low threshold supersaturated absorption. It turns out to be one requirement to achieve the material.

(Effect of overlap of absorption wavelength of photosensitizer and long excited state lifetime dye on reverse supersaturated absorption characteristics)

Comparative Example 5
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (6) having the structure of the following chemical formula 13 was used as the long excited state lifetime dye, and various values were measured.

Comparative Example 6
In Example 1, a sample was prepared and various values were measured in the same manner as in Example 1 except that the dye (7) having the structure of the following chemical formula 14 was used as the long excited state lifetime dye.

Comparative Example 7
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (8) having the structure of the following chemical formula 15 was used as the long excited state lifetime dye, and various values were measured.

Comparative Example 8
In Example 1, a sample was prepared in the same manner as in Example 1 except that the dye (9) having the structure of the following chemical formula 16 was used as the long excited state lifetime dye, and various values were measured.

When Example 1 is compared with Comparative Examples 5 to 8, Comparative Examples 5 to 8 have the absorption of the ground state of the long excited state lifetime dye near the absorption wavelength end of the photosensitizer (see FIG. 8). , Σ ₂ / σ ₁ becomes smaller (see Table 3). As a result, the linear transmittance is significantly reduced, but the transmittance decrease at 1 W / cm ² is small. This means that normally only the photosensitizer absorbs light and it is desirable that the energy be used only efficiently to form the long-lived triplet excitons of the long-excited state lifetime dye, This indicates that the light absorption of the dye is present in the absorption region of the photosensitizer, which inhibits the formation of triplet excitons of the dye (see FIG. 8). Further, when the long excited state lifetime dye absorbs light, the intersystem crossing efficiency is small, and thus the long lifetime triplet excitons of the long excited state lifetime dye are not easily formed, resulting in poor efficiency.
Thus, in the material of the present invention, the peak top of the extinction coefficient at the UV-visible region absorption wavelength in the ground state of the long excited state lifetime dye is on the shorter wavelength side than the UV-visible region absorption wavelength band of the photosensitizer. It can be seen that the requirement is important.

(Difference in reverse supersaturated absorption characteristics due to difference in photosensitizer)

Comparative Example 9
In Example 1, a sample was prepared in the same manner as in Example 1 except that the photosensitizing dye (4) having the structure of the following chemical formula 17 was used as the photosensitizer and the dye (1) was used as the long excited state lifetime dye. Various values were measured.

When a photosensitizer that is not a metal complex is used as in Comparative Example 9, the linear transmittance is large, but the decrease in transmittance at a light intensity of 1 W / cm ² or less is extremely small. In the case of Comparative Example 9, the phosphorescence quantum yield is as small as 0.09, and the light absorption coefficient in the visible light region of a normal photosensitizer is very small and visible at a level of 10 ¹ cm ⁻¹ M ^−1. The material that absorbs the region is also limited. For this reason, even if φτ is large, sufficient photosensitization does not occur because the light absorption efficiency of the sensitizer itself is poor. This can also be seen from the large linear transmission in a 1 mm thick medium in Table 4.

On the other hand, as in Examples 1 to 5, many metal complexes have a wide range of absorption based on electronic transition (Metal to Ligand Charge Transfer (MLCT) transition) between a central metal and a ligand. . The absorption coefficient σ ₁ of this MLCT absorption is smaller than the absorption coefficient σ ₁ of ordinary organic dyes, but is sufficiently larger than the absorption coefficient σ _{1 in} the visible light region of sensitizers other than metal complexes. This moderate absorption coefficient of the metal complex is suitable for maintaining a large linear transmittance. On the other hand, it is possible to obtain sufficient absorption for photosensitization without being too small. Since the absorption coefficient is 10 ³ cm ⁻¹ M ⁻¹ or less, the absorption coefficient value of transient absorption in the excited triplet of the long excited state dye is 10 ⁴ cm ⁻¹ M ⁻¹ or more. If the transient absorption wavelength band in the excited triplet of the excited state dye matches the MLCT absorption band of the metal complex, it contributes to a large σ. As a result, when excitons are accumulated, a large decrease in transmittance is produced, and when the light irradiation is about 1 W / cm ² , the transmittance is reduced to 90% or less, preferably half or less of the linear transmittance. Thus, in the material of the present invention, it can be seen that the condition that the photosensitizer is an organometallic complex is one of the preferable requirements for producing a low threshold reverse supersaturated absorption characteristic.

(Effect of degree of ease of excited triplet energy transfer from photosensitizer to long excited state lifetime dye on reverse supersaturated absorption characteristics)

Example 11
In Example 1, except that the photosensitizing dye (2) having the structure of the above chemical formula 5 is used as a photosensitizer and the dye (10) having the structure of the following chemical formula 18 is used as a long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

Example 12
In Example 1, except that the photosensitizing dye (2) having the structure of the above chemical formula 5 is used as a photosensitizer and the dye (11) having the structure of the following chemical formula 19 is used as a long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

Example 13
In Example 1, the photosensitizing dye (5) having the structure of the following chemical formula 20 was used as the photosensitizer, and the dye (2) having the structure of the above chemical formula 4 was used as the long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

Examples 11 to 13 are materials having a small difference ΔE in the lowest excited triplet level (T ₁ level) between the photosensitizer and the long excited state lifetime dye. In this case, as shown in Table 5, the threshold value indicating reverse supersaturated absorption characteristics is high, and as a result, when the light irradiation is 1 W / cm ² or less, the transmittance is about 0.84 to 0.89 times the linear transmittance. Therefore, it can be said that it shows sufficient performance in practical use even if it is not excellent. In this case, in order photosensitizers sensitive agent from the excited triplet energy transfer efficiency (phi) is less, Faitau becomes less about 0.012, because it increases the threshold value as a result, the transmittance decreases, 1W / cm ² level It can be seen that the light intensity cannot be reduced to less than half of the linear light transmittance.

On the other hand, in the case of Examples 1 to 5, it is a material having a large ΔE, and the excitation triplet energy transfer efficiency (φ) is large from the photosensitizer. For this reason, φτ is increased, and as a result, the threshold value for decreasing the transmittance is decreased, and a decrease in the transmittance starts to occur at the light irradiation level of 1 mW / cm ^{2. At} the light intensity of 1 W / cm ² level, the linear transmittance is reduced. It becomes possible to reduce the transmittance to less than half. Thus, in the material of the present invention, that T ₁ level position of the photosensitizer is greater than T ₁ level of the long excited state lifetime dyes, important requirement of the present invention produces a reverse saturable absorption characteristics of the low threshold It is clear that this is one of the requirements.

(Comparison with conventional organic materials showing good reverse saturable absorption characteristics)

Comparative Example 10
In Example 1, instead of using a photosensitizer or a long excited state lifetime dye, a sample was prepared in the same manner as in Example 1 except that 1.0 part by mass of the dye (12) having the structure of the following chemical formula 21 was used. Prepared and measured various values.

Comparative Example 11
In Example 1, instead of using a photosensitizer and a long excited state lifetime dye, the same as Example 1 except that 1.0 part by mass of the photosensitizing dye (2) having the structure of the above chemical formula 5 is used. Samples were prepared and various values were measured.

In Comparative Examples 10 and 11, no decrease in transmittance is observed as shown in FIG. This is because, as shown in Table 6, the excitation triplet lifetime is short and φτ is remarkably reduced, so that excitation triplets are difficult to store during light irradiation, and the threshold value for transmittance decrease is increased. The dye (21) used in Comparative Example 10 is a compound introduced as a material in which a decrease in transmittance occurs instantaneously upon irradiation with a YAG laser introduced in Non-Patent Documents 3 and 4. Theoretically, φτ is 100000 times larger than that of the example, so that a decrease in the transmittance is not observed unless light with a power of about 1 kW / cm ² is constantly irradiated. Thus, as defined in the present invention, a long excited triplet state lifetime of a long excited state lifetime dye in a room temperature atmosphere is one of the important requirements for producing a threshold reverse supersaturated absorption characteristic. I understand.

(Difference in reverse supersaturated absorption characteristics due to difference in triplet excitation lifetime of long-excited-state lifetime dyes)

Comparative Example 12
In Example 1, except that the photosensitizing dye (2) having the structure of the above chemical formula 5 is used as the photosensitizer and the dye (13) having the structure of the following chemical formula 22 is used as the long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

Comparative Example 13
In Example 1, the photosensitizing dye (2) having the structure of the above chemical formula 5 was used as a photosensitizer, and the dye (14) having the structure of the following chemical formula 23 was used as a long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

Comparative Example 14
In Example 1, except that the photosensitizing dye (2) having the structure of the above chemical formula 5 is used as a photosensitizer, and the dye (15) having the structure of the following chemical formula 24 is used as a long excited state lifetime dye. Samples were prepared in the same manner as in Example 1, and various values were measured.

In Examples 1 to 5, the triplet excited state lifetime of the long excited state lifetime dye is 0.3 seconds or longer in the steroidal alcohol compound and τ is large. As a result, φτ increases, and the threshold value indicating reverse supersaturated absorption characteristics decreases to about 1 mW / cm ² .

On the other hand, as shown in Table 7, in Comparative Examples 12 to 16, the triplet excited state lifetime of the long excited state lifetime dye is 0.3 seconds or less in the steroidal alcohol, and as a result, φτ is small. Become. As a result, the threshold value indicating the reverse supersaturated absorption characteristic is increased, and the transmittance change of 1 W / cm ² or less is reduced.

Comparing Example 1 with Comparative Examples 12 and 13, when using a long-excited-state-life dye having a deuterium substitution, the excited triplet lifetime of the long-excited-state lifetime dye basically increases, Although the threshold of the reverse supersaturated absorption property is lowered, the excited triplet lifetime (τ) of the long excited state lifetime dye is 0.3 seconds or less even when the long excited state lifetime dye is substituted with deuterium. There are also small pigments. As a result, φτ is also reduced, and the threshold value of the reverse supersaturated absorption characteristic is increased. As a result, the linear transmittance can be kept large, but the decrease from the linear transmittance in light irradiation of 1 W / cm ² or less remains small and does not show good reverse supersaturated absorption characteristics. Thus, in the material of the present invention, the requirement that the excited triplet lifetime of the long excited state lifetime dye is 0.3 seconds or more is one of the basic conditions for exhibiting a good low threshold reverse supersaturated absorption characteristic. It turns out that it is.

On the other hand, as shown in Table 7, when Example 1 and Comparative Example 14 were compared, the value of the triplet excited state lifetime (τ) of the long excited state lifetime dye substituted with deuterium was 10 times. It becomes large (FIG. 14B). In Example 1, Chemical Formula 2 which is a deuterium substitution of Chemical Formula 24 which is a long excited state lifetime dye is used, and the increase in τ due to this deuterium substitution increases the value of φτ, and reverse supersaturation absorption characteristics It can be seen that the threshold value is lowered. Thus, it can be seen that in the material system of the present invention, it is preferable that the long excited state lifetime dye is a dye whose lowest excited triplet state is a ππ ^* transition, and that the aromatic ring is substituted with deuterium.

(Examination of difference in blending amount of photosensitizer)

Example 14
In Example 1, a sample was prepared in the same manner as in Example 1 except that the amount of the metal complex (1) was 0.5 parts by mass, and various values were measured.

Example 15
In Example 1, a sample was prepared in the same manner as in Example 1 except that the compounding amount of the metal complex (1) was 5.0 parts by mass, the thickness of the spacer was about 100 μm, and the thickness of the medium was 100 μm. Various values were measured.

Example 16
In Example 1, a sample was prepared in the same manner as in Example 1 except that the amount of the metal complex (1) was 0.1 parts by mass, and various values were measured.

  As shown in Table 8, when Examples 14 and 15 are compared with Example 16, when the photosensitizer concentration is low as in Example 16, the value of φτ is large and the value of σ is large. However, although it does not show the decrease of the transmittance | permeability as favorable as Example 14 and 15, it can be said that the performance is practically sufficient. This is because the photosensitizer light absorption itself becomes too weak at the optical length of 1 mm of the medium because the photosensitizer concentration is too thin. This can be seen from the large linear transmittance.

On the other hand, in Examples 14 and 15, as shown in Table 8, the concentration of the photosensitizer is appropriate, and the device does not crystallize. Also, due to the large φτ and the large σ, the threshold of reverse supersaturation absorption characteristics is low, high linear transmittance in light irradiation with weak power of 0.1 mW / cm ² , and small in steady light of 1 W / cm ² Both transmittances can be realized, that is, a low threshold and good reverse supersaturated absorption characteristics are exhibited.

(Examination of difference in blending amount of long excited state lifetime dye)

Example 17
In Example 1, a sample was prepared in the same manner as in Example 1 except that the amount of the dye (1) having the structure of the above chemical formula 2 as a long excited state lifetime dye was 3.0 parts by mass. Measurements were made.

Example 18
In Example 1, a sample was prepared in the same manner as in Example 1 except that the blending amount of the dye (1) having the structure of Chemical Formula 2 as a long excited state lifetime dye was 0.5 part by mass. Measurements were made.

Example 19
In Example 1, a sample was prepared in the same manner as in Example 1 except that the amount of the dye (1) having the structure of the above chemical formula 2 as a long excited state lifetime dye was 1.0 part by mass. Measurements were made.

Example 20
In Example 1, a sample was prepared in the same manner as in Example 1 except that the amount of the dye (1) having the structure of the above chemical formula 2 as a long excited state lifetime dye was 10.0 parts by mass. Measurements were made.

As shown in Table 9, Examples 1 and 17 increase the probability that the photosensitizer is adjacent to the long excited state lifetime dye, and excited triplet energy transfer from the photosensitizer to the long excited state lifetime dye. There (large phi _ET) efficiently occurs, resulting φτ increases, long life triplet excitons efficiently long excited state lifetime dye is likely to be accumulated. As a result, the transmittance at the time of light irradiation is greatly reduced, and the transmittance at the time of light irradiation of 1 W / cm ² is reduced to less than half of the linear transmittance while maintaining the linear transmittance at 50% or more as shown in FIG. To do.

Meanwhile, Examples 18 and 19, long excited state lifetime triplet energy transfer efficiency from the photosensitizer to the long excited state lifetime dyes to dye less is not sufficient (phi _ET is small), Faitau small Become. Therefore, the long-lived triplet excitons of the long-excited-state lifetime dye are not easily accumulated, and the linear transmittance can be ensured to be 50% or more as shown in FIG. ^{Although the} degree of decrease in transmittance due to the light irradiation of No. 2 does not show a good decrease in transmittance as in Examples 1 and 17, it can be said that it shows sufficient performance in practical use.

In Example 20, since the number of long excited state lifetime dyes is small, the excited triplet energy transfer efficiency from the photosensitizer to the long excited state lifetime dye is large ( _φET is large). Due to the influence of the aggregate, the excited triplet lifetime becomes shorter (τ becomes smaller) and φ becomes smaller. Therefore, the long-lived triplet exciton of the long-excited state lifetime dye is not easily accumulated, and the linear transmittance can be ensured to be 50% or more, but the transmittance due to light irradiation of 1 W / cm ² can be secured. Although the degree of reduction is not as good as in Examples 1 and 17, it can be said that the practical performance is sufficient.

(Influence on reverse supersaturated absorption characteristics with and without photosensitizer)

Comparative Example 15
In Comparative Example 5, a sample was prepared in the same manner as in Comparative Example 5 except that no photosensitizer was used, and various values were measured.

As shown in Table 10, in the case of Comparative Example 15, the excited triplet lifetime of the dye is as long as seconds (τ is large). In the wavelength region of 405 nm, the extinction coefficient is small as shown in FIG. 11, and the extinction coefficient of transient absorption of the excited triplet is large in the wavelength region of 405 nm, so σ is large. However, the intersystem crossing efficiency of the material is small and φ is small. As a result, φτ is not sufficiently large, and the exciton accumulation capacity is not sufficient. As a result, the decrease rate of the transmittance at a light intensity of 1 W / m ² is small.

The low-threshold organic reverse supersaturated absorbing material and medium of the present invention have high transparency with respect to light in the visible light range, and do not scatter light even in a medium with a thickness of 1 mm. Have. On the other hand, it has a feature that the absorbance of the material increases instantaneously only when intense light is irradiated. This strong light power is light of several mW / cm ² to several W / cm ² level as in an LED or a semiconductor laser. When the light intensity is weak, the light transmittance is 10% or more, preferably 50% or more, and at the light irradiation intensity of 1 W / cm ² , the saturated transmittance is 90% or less, preferably half of the linear transmittance. It can be reduced to: The medium can be used by being sandwiched between substrates such as a casting method or a liquid crystal element.

  The threshold of response of the low threshold organic reverse supersaturated absorbent material of the present invention is as low as at least 1 / 10th power level compared to that of the original organic material. For this reason, the conventional organic reverse supersaturated absorption material responds instantaneously only to a large and expensive YAG laser with a large pulse having a high instantaneous intensity. It is a material that responds to strong sunlight.

  On the other hand, the low threshold is sufficiently small even when compared with reverse supersaturated absorbent materials of inorganic compounds. Furthermore, it is possible to easily increase the area of the reverse supersaturated absorption medium, which was difficult with inorganic compounds.

  As described above, since the material of the present invention can control reverse supersaturation absorption characteristics without using a large and expensive pulse laser, a small high-speed optical switch material using a small and inexpensive light source, a high-speed optical logic operation element, etc. It is possible to use for the optical system. Further, since a reverse supersaturated absorber having a large area can be formed, it can also be applied to a strategy of a light control element or a security element. In addition, it is difficult to control with laser spot light sources such as displays and displays with new strategies because it is possible to control reverse supersaturated absorption function over a large area using non-coherent light. This makes it possible to construct a simple optical system. As described above, the present low threshold organic reverse supersaturated absorbing material and its medium are expected to be applied to various fields.

Claims (10)

Light having a diffusion coefficient of less than 10 ^-15 cm ² / s at room temperature, an intersystem crossing efficiency of 50% or more, and a phosphorescence quantum yield of 10% or more at room temperature in a matrix forming a disordered state. A material containing a sensitizer and a long excited state lifetime dye having a lifetime of an excited triplet lifetime of 0.3 seconds or longer in a 77K rigid medium,
The lowest excited triplet energy of the photosensitizer is greater than the lowest excited triplet energy of the long excited state lifetime dye,
The absorption coefficient of transient absorption of the excited triplet state of the long excited state lifetime dye is larger than the absorption coefficient of the ground state of the photosensitizer at a wavelength of 400 to 600 nm, and the ultraviolet visible region of the ground state of the long excited state lifetime dye A reverse supersaturated absorbing material characterized in that the peak top of the extinction coefficient at the absorption wavelength is on the shorter wavelength side than the ultraviolet-visible region absorption wavelength band of the photosensitizer.   The reverse supersaturated absorbent material according to claim 1, wherein the matrix is a condensed polycyclic compound having at least one cyclo ring and one OH group. The fused polycyclic compound, reverse over-saturation absorbing material according to claim 2 is a steroidal alcohol.   The reverse supersaturated absorbing material according to any one of claims 1 to 3, wherein the photosensitizer is an organometallic complex.   The product (φτ) of the quantum yield (φ) and excited triplet state lifetime (τ) of the excited triplet state formation in the long excited state lifetime dye when irradiated with light of a predetermined wavelength is 0.01 or more The reverse supersaturated absorbent material according to claim 1. The long-excited-state lifetime dye is a dye whose lowest excited triplet state is a ππ ^* transition and does not contain an atom having an atomic number of 9 or more in the molecule. Reverse supersaturated absorbent material.   The reverse supersaturated absorbing material according to claim 1, wherein the long excited state lifetime dye has an aromatic ring, and the aromatic ring is substituted with deuterium. The reverse supersaturated absorbing material according to any one of claims 1 to 7, wherein the linear transmittance at a light intensity of 1 µW / cm ² is 50% or more.   A reverse supersaturated absorbent medium, wherein the reverse supersaturated absorbent material according to claim 1 is used. Conversely saturable absorber medium of claim 9, reverse over-saturation absorbing material, characterized in that provided on the substrate.