JPH07175420A - Light input type organic el element - Google Patents

Abstract

PURPOSE:To obtain such as EL element that enables input of optical information and has various functions such as switching, memory and multiple input by providing an org. thin film having a light emitting display part and an optical response part, and a pair of electrodes to apply voltage on the org. thin film so that light emitting display is performed according to the input of optical information. CONSTITUTION:This element has an org. thin film having a light emitting display part 17 and an optical response part 13, and a pair of electrodes to apply voltage to the thin film. When the optical response part 13 is irradiated with intense light, the electric conductivity of the optical response part 13 increases and holes are injected from the electrode 12 to inject holes to the optical response part 13. Thereby, about 10V which is almost equal to the voltage applied between the electrodes is applied on the light emitting display part 17. As a result, electrons are injected from the electron injecting electrode 18 to the light emitting layer 15 through an electron injecting layer 16, while holes are injected from the hole injecting electrode 12 to the light emitting layer 15 through the optical response part 13 and a hole injecting layer 14. Thus, electrons and holes are coupled again to emit light in the light emitting layer 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light input type organic EL element capable of writing external information by an optical input method and capable of emitting display according to the external information.

[0002]

2. Description of the Related Art In recent years, various information input / output devices have been dramatically improved with the rapid progress of information systems.
Currently, liquid crystal devices and CRTs are the mainstream display devices as interface devices between computers and users. Among them, liquid crystal devices are thin and lightweight and have low driving power consumption, and are expected to continue to develop as display devices.

However, the liquid crystal device also has an unavoidable drawback in view of its operating characteristics. For example, it requires a backlight light source, has a slow response speed, has a narrow viewing angle, is difficult to have a large screen, and has a poor display contrast under bright light. In order to overcome such drawbacks, light emitting display devices such as plasma displays, inorganic EL panels, vacuum microcathode devices, etc., have been attracting attention. However, these light-emitting display elements have problems such as insufficient brightness, difficulty in multicolor display, and high driving voltage.

On the other hand, recently, a carrier injection type electroluminescent device (organic EL device) having a laminated structure of organic thin films.
At 1000 cd / m at low voltage drive around 10 V
It has been reported that a high-luminance light emission of ² or more can be realized. In such an organic EL element, the emission color substantially matches the fluorescent color of the organic dye used, so that multicolor display can be easily realized by appropriately selecting the organic dye. Further, since the organic thin film can be easily formed by the vapor deposition method, it is also advantageous for increasing the area. As described above, the organic EL element is highly expected as a display device capable of avoiding the drawbacks of the liquid crystal device and greatly improving the display performance, and technical development for practical use is being vigorously advanced. .

On the other hand, information systems tend to be more and more diversified in the future, and the importance of both hardware and software technology for interfaces is also increasing. For example, the current input format is mainly a keyboard and a mouse, but recently, a pen input type personal computer and a dedicated OS therefor have been developed.
As described above, the input form to the computer is required to be more suitable for human sensitivity and behavior than the keyboard and mouse, and the variety according to the operating conditions of the system or the use environment of the computer is required. It is thought to be done. Further, the output format of information is required to have not only a simple display function as in the past, but also an advanced function according to the system. Therefore, the organic EL element is required to have not only characteristics as a high-performance display device but also characteristics having an information input function, a storage function, a storage function, and the like.

Further, in the input device which can be input conventionally used, since the information input element and the display element are separately configured, information detection and display driving are performed by completely different circuits. It was In addition to this, the display operation for the input information needs to be performed by a device for information processing, which is completely different from the mechanism for inputting information and the mechanism for display.

For example, as described above, in recent years, various pen input type liquid crystal display elements have begun to spread as an input / output device that places importance on human usability. With these devices,
A device for detecting input from a pen is attached separately from the liquid crystal display having a display function. There are various types of pen input devices, such as one that detects writing pressure by the pen, one that detects electromagnetic waves generated from the pen, and one that detects light input by the pen. And the liquid crystal display method are mechanically different from each other. Therefore, information processing by a computer is required to display and output the input information.
In other words, the information entered by the pen is detected by the computer once the coordinates and pattern entered,
By using the image information obtained by processing these as the input signal of the liquid crystal display operation, only the pen input type display element is configured as the entire system. Of course, in order to display the pen input information as an image in the above procedure, a considerable amount of computer calculation is required, so the input detection capability is slow and system programming is difficult. It becomes a big problem. As a result, the current pen-input type liquid crystal display device is not always a tool easy for humans to use.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical input type capable of inputting information by light and emitting display corresponding to the information, and further having a function of accumulating and storing optical input information. It is to provide an organic EL device.

[0009]

A light input type organic E of the present invention
The L element includes an organic thin film having a light emitting display unit and a light response unit, and a pair of electrodes for applying a voltage to the organic thin film, and light emission display is performed according to information optically input. It is what

In general, the light input type organic EL device of the present invention comprises one layer or a plurality of layers of organic thin film constituting the light emitting display section and one layer or a plurality of layers of organic thin film constituting the photoresponsive section. The laminated organic thin film is provided with a pair of electrodes for electron injection and hole injection for injecting carriers. Here, the stacking order of the light emitting display section and the photoresponsive section is not particularly limited. Further, at least a part of the organic thin film forming the light emitting display section may form a light response section, and light emission display may be performed by the forward bias and light input may be detected by the reverse bias.

In the present invention, it is preferable that the organic thin film forming the photoresponsive portion exhibits a switching response. Further, as the organic thin film forming the photoresponsive portion, a thin film that reversibly changes with light of a plurality of different wavelengths is used, whereby a memory function can be exhibited. Furthermore, for example, if the photoresponsive portion is formed by organic thin films in which a plurality of materials are two-dimensionally patterned or laminated to form regions showing a response to lights of different wavelengths, these different wavelengths can be formed. It is possible to add a multiplex input function using a plurality of lights having a. It is also possible to dope the organic thin film forming the photoresponsive portion with impurities and change the responsiveness to light according to the concentration of the impurities.

The present invention will be described in more detail below.

In the present invention, the substrate is glass;
Resins such as polyethylene, polypropylene, polyester and polycarbonate; metal sheets such as steel sheets and stainless sheets are used.

In the present invention, the light emitting display section has the same structure as a normal organic EL element and operates on the same principle.
The light emitting display unit will be described with reference to FIG. As shown in FIG. 14, the structure of the light emitting display section includes a hole injection layer ( _OH ) 2 between a hole injection electrode ( _MH ) 1 and an electron injection electrode ( _ME ) 5, It is typical that the light emitting layer ( _OL ) 3 and the electron injection layer ( _OE ) 4 are formed. The laminated structure of the organic thin films forming the light emitting display section is not limited to the three-layer structure as described above, but may be a two-layer structure of an electron injection layer and a light emitting layer or a two layer structure of a hole injection layer and a light emitting layer. And so on. In addition, at least one of the electron injection layer, the light emitting layer, and the hole injection layer may have a multilayer structure of four or more layers including a plurality of layers. Furthermore, each organic thin film may be made of a single material, or two or more kinds of materials may be mixed. These configurations are determined according to the performance required for the device, such as emission color, operating voltage, brightness, and response speed.

With respect to the light emitting display section of FIG. 14, the bonding state when no voltage is applied is shown in FIG. 15A, and the bonding state when a voltage is applied is shown in FIG. To do. The bonding state of each layer in FIG. 15A is as follows. An electron injecting junction is formed between the electron injecting electrode (M _E ) 5 and the electron injecting layer (O _E ) 4. A junction having an electron injecting property and a hole blocking property is formed between the electron injecting layer (O _E ) 4 and the light emitting layer (O _L ) 3. On the other hand, a hole injecting junction is formed between the hole injecting electrode ( _MH ) 1 and the hole injecting layer ( _OH ) 2. A junction having a hole injecting property and an electron blocking property is formed between the hole injecting layer ( _OH ) 2 and the light emitting layer ( _OL ) 3. Now, when a negative voltage (forward bias) is applied to the electron injection electrode 5, electrons are emitted from the electron injection electrode 5 via the electron injection layer 4 as shown in FIG.
Meanwhile, holes are injected from the hole injecting electrode 1 through the hole injecting layer 2 into the light emitting layer 3. And the light emitting layer 3
The electrons and holes recombine therein. The energy at this time is converted into photons to emit light (electroluminescence). Therefore, in principle, light emission with a wavelength corresponding to the band gap of the light emitting layer 3 can be obtained.

In this case, when the forward bias applied between the electrodes is increased, the density of electrons and holes injected from the electrodes is increased, and the emission brightness is increased. Therefore, the emission brightness can be controlled by the applied voltage. The range of applied voltage is set to 1 to 10 V, and the current density at this time is 1 to 100 mA / cm ² . On the other hand, when a reverse bias is applied between the electrodes, carrier injection from the electrodes does not occur and no current flows through the element (rectifying characteristic), so that no light is emitted.

Materials used for the light emitting display section will be specifically described. A photoluminescent dye derivative is used for the light emitting layer. The photoluminescence property is a property in which a photon is emitted from its excited state when the dye is excited with light having a wavelength at which the dye absorbs light. In the present invention, it is preferable to select one having a particularly high efficiency. For the electron injection layer and the hole injection layer, a material that causes electron injection and hole injection when in contact with the electrodes is used. The materials having the above properties can be examined by the displacement current measuring method developed by the present inventors.

Next, the optical response section will be described. At least one layer of the organic thin film forming the photoresponsive portion is made of a material exhibiting a property that its electrical properties change significantly when absorbing light. Here, examples of the electrical properties include change in conductivity due to light (photoconductivity), current generation due to photoinduced carrier generation (photoelectromotive current), voltage generation due to light (photoelectromotive voltage), and the like. Regarding the aspect of the change in the electrical properties of the photoresponsive portion, there can be mentioned non-linear response such as switching response and memory response based on optical bistability. The material exhibiting such properties may be either a low molecular weight compound or a high molecular weight compound, and examples thereof include the following.

Materials exhibiting photoconductivity, that is, materials in which the transport / injection characteristics of the carrier injected from the electrode by irradiation of light are changed, are perylenetetracarboxylic acid diimide derivatives, tetrapyridylporphyrin derivatives, pyrylium dyes, polyacene derivatives. , Various charge transfer complexes, and the like. With respect to the photoresponsive section made of such a material, the carrier injection property to the light emitting display section can be controlled by light. FIG. 16 shows the result of measuring the carrier injection characteristics of the organic thin film made of such a material by the displacement current measuring method. When such an organic thin film is not irradiated with light, it is almost close to an insulator as indicated by a solid line, but it is improved in carrier transport / injection property as indicated by a broken line by light irradiation.

Examples of materials that generate photo-induced carriers include the following. For example, M ・ TC
NQ (tetracyanoquinodimethane), M.TNAP (tetracyanonaphthoquinodimethane), M.DCNQI (dicyanoquinodiimine) (where M is Cu, Ag, Au)
The composition of a complex such as a metal ion) changes when it is irradiated with laser light having an appropriate wavelength. Of these, Cu / TC
NQ is an “ionic” complex that behaves almost as an insulator when it is not irradiated with light, but when irradiated with laser light having a wavelength of 510 nm, part of the complex becomes “neutralized”.
To do. As a result, the electric conductivity in the irradiated portion is increased 10 ³ to 10 ⁴ times as compared with that in the non-irradiated portion, and remarkable non-linear electric conductivity is exhibited. In addition, the polydiacetylene derivative undergoes an AB type structural phase transition upon irradiation with light, and the photoconductivity greatly changes. In addition, the alternately laminated type TTeC ₁ TTF-TC
NQ is a strong electron peculiar to quasi-one-dimensional system due to light irradiation.
Due to lattice interaction, a large number of carriers are generated with the domain wall as elementary excitation. The photoresponsive portion made of such a material itself functions as a carrier injection layer when irradiated with light.

An example of the light input type organic EL element of the present invention is
It has a structure in which the organic thin film of the light emitting display section and the organic thin film of the photoresponsive section made of the above-mentioned materials are laminated, and a pair of electrodes is provided above and below them. Even if a forward bias is applied to the light emitting display section between the upper and lower electrodes, no current flows if the light responsive section is not irradiated with light. on the other hand,
When a forward bias is applied between the upper and lower electrodes and the photoresponsive portion is irradiated with light, the photoresponsive portion becomes highly conductive and sufficient carriers are injected from the electrodes. Further, the carriers are transported from the photoresponsive portion to the adjacent light emitting display portion, resulting in light emission. When the material of the photoresponsive portion has bistability in which a change in electrical properties is retained once light is absorbed, the light emission continues even if the input light is extinguished.

In the device of the present invention, the electrical detection of the light input can be realized, for example, by measuring the current flowing when the forward bias is applied for the light emitting display operation.
That is, when the light responsive portion is not irradiated with light, carrier injection does not occur and light emission does not occur because the electrical conductivity is low. On the other hand, when the light responsive portion is irradiated with light, the electrical conductivity is increased and carriers are injected, resulting in light emission. When the irradiation of light is stopped, the electrical conductivity of the photoresponsive portion is lowered again and the light emission is stopped. Therefore, the light input can be detected by detecting the amount of current flowing when the forward bias is applied.

In the device of the present invention, at least one layer of the organic thin film forming the light emitting display part may have a property of generating carriers by absorbing light and acting as a photoresponsive part. At this time, the organic thin film acting as the photoresponsive portion may be any of an electron injection layer, a light emitting layer, and a hole injection layer. In this case, it is advantageous to apply an AC bias with a frequency of 30 Hz or higher to the device and detect the optical input when the device is reverse biased. That is, when the device is irradiated with light during reverse bias, a photocurrent is generated from the organic thin film of the photoresponsive portion and flows out of the device from the electrode. By electrically detecting this photovoltaic current, it is possible to detect that light is input. Further, by designing an appropriate detection circuit and drive circuit, it is possible to raise the forward bias based on the signal of the optical input detected at the time of the reverse bias and perform light emission display. Hereinafter, such an element is referred to as a reflex type.

In the device of the present invention, it is preferable that the photoresponsive portion cause a switching response, that is, a threshold change of carrier density that can be injected into the light emitting display portion according to the intensity of the irradiated light. Such a switching response is important in that the influence of background light is reduced, such that the device operates only when it is irradiated with intense light.

In the device of the present invention, a variety of functions can be realized by forming the photo-responsive portion with a plurality of organic thin films of two or more layers. Here, in order to simplify the following description, among the two layers of organic thin films forming the photoresponsive portion, the organic thin film on the side adjacent to the light emitting display portion is referred to as the lower photoresponsive portion and the organic material on the side irradiated with light. The thin film is used as the upper layer photoresponsive portion.

First, if a material that selectively responds to light of a specific wavelength is used as the upper layer photoresponsive section that constitutes the photoresponsive section,
It can function as a filter layer for background light.

Further, even if a material which selectively responds to light having a specific wavelength and exhibits photochromic properties is used as the upper photoresponsive portion which constitutes the photoresponsive portion, it can function as a filter layer against background light. The absorption characteristics of such a light response portion will be described with reference to FIG. In this case, as the lower layer photoresponsive portion, a material exhibiting photoinduced carrier injection characteristics when irradiated with light of wavelength λ ₁ is used as described above. In addition, a material having the following absorption characteristics is used for the upper layer photoresponsive section. That is, when it is not irradiated with light, it has an absorption maximum at λ 2 _mA and has an absorption at a region of wavelength λ ₁ where the lower layer photoresponsive portion becomes active. On the other hand, when the light of wavelength λ _2A is irradiated, the absorption maximum shifts to λ _2mB and almost no absorption occurs in the region of λ ₁ .
Now, even when the light of λ ₁ is irradiated, the light is absorbed by the upper layer photoresponsive portion, so the lower layer photoresponsive portion does not function as a carrier injection layer. However, when the upper layer photoresponsive portion is irradiated with light of λ _2A and its absorption maximum is shifted to λ _2mB , λ ₁
When irradiating the above-mentioned light, the lower photoresponsive portion functions as a carrier injecting layer to emit light. In such a configuration, the upper photoresponsive portion acts as a filter layer, and is effective in blocking background light when the device of the present invention is used.
Examples of the upper photoresponsive portion having such a function include organic materials exhibiting photoionization such as tetraalkyl-p-phenylenediamine derivatives; organic photochromic materials such as spiropyran and fulgide.

Further, a case will be described in which an organic nonlinear optical material exhibiting a threshold photoresponsiveness, for example, an SHG (second harmonic generation) material is used as the upper photoresponsive part constituting the photoresponsive part having a two-layer structure. . As shown in FIG. 18 (a),
The SHG material exhibits a non-linear output response of generating a light output of 2ω that is proportional to the square of the intensity of the irradiation light ω. As shown in FIG. 18B, the lower layer photoresponsive section exhibits a switching response due to this output light.

With respect to the device of the present invention having the above structure, a system for controlling the light emitting display operation and the light response operation will be described with reference to FIGS. 19 and 20.
In the device of the present invention, light emission occurs when the injected carrier density reaches an effective value (η _eff ) in the light emitting display section.
In the conventional device, in order to secure η _eff , the carrier density is changed along the curve 1 in FIG.
Only the circuit for controlling the current value was provided. On the other hand, in the device of the present invention, the carrier density can be increased or decreased by the light energy above a certain threshold. Therefore, a circuit for controlling the voltage / current value and a circuit for controlling the irradiation light intensity are provided so that the carrier density changes along the curve 2 in FIG. That is, FIG.
As shown in 0, a voltage / current control system 81 for controlling voltage / current between electrodes, an optical input control system 82 for controlling irradiation light intensity, and writing for controlling both control systems. A control system having a display control system 83 is used.

In the device of the present invention, a memo is provided in the photoresponsive portion.
It can also be provided with a re-function. Specifically, the optical response unit
Is an organic thin film made of a material that generates photo-induced carriers.
(Lower layer photo-responsive part) and organic thin film with memory function (upper layer
It has a laminated structure with an optical response part). On having memory function
The layer photo-responsive part is, for example, by light of two different wavelengths.
A material whose absorption characteristics change reversibly is used. Lower layer light
Response part has wavelength λ₁Of light-induced carriers
To occur. The upper layer photo-responsive part uses two different wavelengths of light.
Its absorption characteristics change reversibly. That is, FIG.
As shown in (a), when no light is emitted, the absorption pole
Large is λ_2mAIn λ₁Has no absorption in the region of
λ_2AThe maximum absorption is λ_2mBChanges to λ₁
It has absorption in the area that overlaps. In addition, FIG.
As shown in (b), λ _2BThe light of
And the absorption maximum is λ_2mBFrom λ_2mAReturn to.

As described above, when the absorption maximum of the upper layer photo-responsive portion is changed from λ _{2 mA} to λ 2 _mB by the irradiation of the light of the wavelength λ _2A , the light of the wavelength λ ₁ is effectively emitted to the lower layer photo-responsive portion under the irradiation portion. No light emission occurs at all. However, in the region where the light of wavelength λ _2A is not previously irradiated, light of wavelength λ ₁ reaches the lower photoresponsive portion, so that light emission occurs.
In this way, the input information by the light of the wavelength λ _2A is recorded in the upper layer optical response portion, and the operation of the element can be controlled by the light of the wavelength λ ₁ corresponding to the recorded information. In addition, the wavelength λ _2A
When the light of wavelength λ _2B is irradiated after irradiating the light of wavelength λ _2A , the absorption maximum changes again from λ _2mB to λ _2mA .
The input information by the light of "is erased". Information can be “written” and “erased” by the light of λ _2A and λ _2B in the upper layer optical response section that constitutes the optical response section, and the lower layer light Since the generation of photo-induced carriers in the response portion can be controlled, the EL light emission operation occurs according to the light input information.

As a material for the upper photoresponsive portion having a memory function, an organic dye whose absorption characteristic is reversibly changed by photoionization or photoisomerization is used. For example,
Photochromic compounds such as tetraalkyl-p-phenylenediamine derivatives and analogs thereof, benzothiopyran spiropyrans, benzylviologen derivatives, pyrenethioindigo, fulgide derivatives, stilbene derivatives and the like can be mentioned. Further, as a material for the upper layer photoresponsive portion having a memory function, a material whose absorption characteristics are changed by light irradiation of two wavelengths, that is, a two-photon reaction, such as biacetyl contained in poly-α-cyanoacrylate ester, is used. You may use.

Further, as a material of the upper layer photoresponsive portion having a memory function, an organic dye whose light transmission characteristic reversibly changes upon irradiation with light may be used. In this case, as shown in FIG. 22, a material having a property that the transmittance is changed by irradiating with the light of wavelength λ _2A and is returned to the original state by irradiating with the light of wavelength λ _2B is used. To be

Examples of the material having the property of reversibly changing the light transmission characteristics include various dye-based liquid crystal materials and polymer-based liquid crystal materials. When these liquid crystal materials are irradiated with light, the transmittance changes remarkably due to a so-called heat mode mechanism. Specific examples of the liquid crystal material include, for example,
Examples thereof include alkylaminobiphenyl-based, alkoxyazobenzene-based, phenylcyclohexane-based liquid crystals; cholesteryl methacrylate / alkyl methacrylate polymer liquid crystals; and discotic liquid crystals such as benzene hexaalkanoate. In addition, as a material having a property of reversibly changing the light transmission characteristics, conductive polymers such as polythiophene and polypyrrole derivatives, and diphenyliodonium perchlorate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroarsenate as photoinduced dopants. It is also possible to use a thin film containing, for example.

In the device of the present invention, the photo-responsive section can be provided with a multiple input function. Such a multiple input function can be realized, for example, by forming a photo-responsive portion having a structure in which a plurality of photo-induced carrier generating materials responsive to different wavelengths are formed in a two-dimensional pattern or a laminated structure. Further, a photo-responsive portion having a structure in which a plurality of materials having a filter function for different wavelengths are formed in a two-dimensional pattern on a single photo-induced carrier generating material may be used. Materials having such a filter function include merocyanine dyes, styryl dyes, azomethine and azo dyes, spiropyran dyes, phenothiazine dyes, triphenylmethane dyes,
Examples thereof include a quinacridone pigment, a quinophthalone dye, a dithiolene complex, a β-diketone complex, an anthraquinone dye, a naphthalimide dye, and an azobenzene dye.

In this case, by using the writing light of a plurality of wavelengths and detecting the photoexcited injection current for each of the plurality of organic thin films arranged in a two-dimensional pattern and having different absorption spectra, the wavelength (color) of the input light is detected. ) May be determined. Further, the light emitting display section may emit only one color of light, or a plurality of light emitting display sections that emit light of different wavelengths may be provided in association with the plurality of photoresponsive sections. Therefore, various display operations can be considered depending on the combination of the wavelength type of the writing light and the emission wavelength type. For example, red / green / blue (RG
Writing is performed by using the light of three colors of B), and if a light emitting display unit is provided so that the wavelength of the writing light corresponds to the light emitting wavelength, such as R light emission for R writing, full color light emission display can be performed. It will be possible. In addition, writing is performed by the light of two colors of RG, and the light emitting display section is configured to emit only G1 color. G light emission occurs for G writing, and G light emission is erased for R writing. If the circuit configuration is adopted, it is possible to configure an EL element that combines a light emitting display function and a writing / erasing function.

In the present invention, the organic thin film forming the photoresponsive portion may be doped with impurities. For example, when the organic thin film of the photoresponsive portion is doped with an acceptor impurity, this organic thin film behaves as a p-type semiconductor. Now, in order to understand the operation of this organic thin film, consider a structure in which this organic thin film is sandwiched between a pair of electrodes (hole injection electrode M _H and electron injection electrode M _E ), and FIG. The joined state is shown. As shown in FIG. 23 (b), when a voltage is applied between the electrodes, holes that have been thermally excited from the hole injecting electrode M _H side into the organic thin film are transferred to the electron injecting electrode M as in a general semiconductor. _It is swept out to the _E side and the energy band bends due to depletion (band bend). At this time, a voltage is applied near the hole injecting electrode M _H, but no voltage is applied to the electron injecting electrode M _E side. That is, holes are injected but electrons are not injected.
If the hole injection electrode M _H having a small work function is used to increase the hole injection barrier, hole injection does not occur and current does not flow when the applied voltage is low. As shown in FIG. 23C, when light having energy higher than the band gap is irradiated in this state, electrons and holes are excited between the bands. The excited holes are trapped by the anionized impurity level, and the impurity level is neutralized. As a result, the bending of the band is reduced, and the voltage is also applied to the electron injection electrode M _E side so that electrons are injected. That is, optical switching for electron injection becomes possible. In contrast to the above, if the organic thin film forming the photoresponsive portion is doped with a donor impurity so that it behaves as an n-type semiconductor, optical switching for hole injection becomes possible.

In order to realize the band bending as described above, the impurity concentration in the photoresponsive portion is controlled. Strictly speaking, the optimum impurity concentration depends on the film thickness of the photoresponsive portion and the applied voltage, but it can be roughly calculated as follows. Here, the applied voltage is V, the thickness at which the organic thin film is depleted is W,
It is assumed that the impurity concentration is N _A , the vacuum dielectric constant is ε ₀ , the relative dielectric constant of the organic thin film is ε, and the unit charge amount is q. Since V is typically above 1 volt, the built-in potential between the electrodes is ignored. In this case, the _{W~ (2εε 0 V / qN A} ) 1/2. Now, assuming that the thickness of the photoresponsive portion is 100 nm, the applied voltage is 10 V, and ε is 5, N _A is about 2 × 10 ¹⁸ /
It becomes cm ³ . That is, in order not to distribute the applied voltage of 10 V to the electron injecting electrode M _E side, 10 ¹⁸
An impurity concentration of / cm ³ or more is required. Actually, since it is not so precise, the impurity concentration is 10 ¹⁷ to 10 ¹⁹
/ Cm ³ is set.

Next, as shown in FIG. 24, the hole injection electrode M
_H, 3 of the hole injection layer O _H / light emitting layer O _L / electron injection layer O _E
Consider a structure including a light emitting display section made of layers, a photoresponsive section made of an organic thin film doped with impurities, and an electron injection electrode M _E. As shown in FIG. 24 (a), when a voltage is applied between the electrodes, but holes are injected into the light emitting layer O _L from the hole injection electrode M _H through the hole injection layer O _H, an electron injection It is blocked and accumulated by the hole injection barrier with the layer O _E. on the other hand,
As described with reference to FIG. 23, almost no voltage is applied to the electron injection electrode M _E due to the band bending of the photo response unit, so that electrons are not injected from the electron injection electrode M _E into the photo response unit. Absent. Since no electrons are injected into the light emitting layer O _{L in} this way, no light emission occurs. As shown in FIG. 24 (b), when light is irradiated in this state, the band bending of the photoresponsive portion disappears, and electrons are emitted from the electron injection electrode M _E through the photoresponsive portion and the electron injection layer O _E. Implanted in layer O _L. As a result, electrons and holes accumulated in the light emitting layer O _L are recombined to emit light.

The element of the present invention can also obtain the following effects as compared with the conventional element. The conventional device has a problem in that a decrease in emission luminance with time is observed. It has been found that this is mainly due to deterioration and deterioration of the joint portion between the metal electrode and the light emitting layer and a consequent decrease in the injected carrier density. In the conventional organic EL element, it is necessary to optimize the voltage and stabilize the light emission characteristics each time such a change occurs. For this reason, for example, when the light emission efficiency becomes low, it is necessary to apply a voltage that is several times higher than that at the time of initial driving, which causes the life of the element to be further shortened. On the other hand, in the device of the present invention, carriers are injected from the metal electrode to the light emitting display unit via the photoresponsive unit. For this reason, unlike the conventional element, deterioration deterioration is unlikely to occur at the joint between the metal electrode and the light emitting layer, and the light emitting characteristics are less likely to become unstable.

Next, the usage of the device of the present invention will be described. There are two methods of inputting information to the device of the present invention using light, that is, a method of holding a light source in hand and a method of collectively transferring information written on paper or the like using light. In any case, it is preferable to use a flexible substrate as a display that is thin and can be flexibly bent like paper. For example, when a light pen is held in the hand for optical input, a feeling similar to handwriting is obtained, which is ergonomically suitable. Also, it is advantageous in terms of adhesion when transferring information written on paper. Furthermore, by sticking the element of the present invention to the surface of another device, it can be used not only as a flat surface but also as a curved surface such as a spherical surface. In such a curved display, the reflected light from the background does not enter the line of sight.

The element of the present invention can be connected to an information processing device such as a computer, a word processor and an electronic notebook via an interface. In this case, the information stored in the memory of the information processing device can be displayed. Conversely, the information input by light can be stored in the memory of the information processing device via the interface.

Further, the element of the present invention can be used as, for example, an optical writing type notebook without connecting to the above information processing equipment. In this case, a material exhibiting optical bistability is used for the photoresponsive portion. In such a usage mode, when information is written, it is continuously displayed and stored and stored as it is. Then, when the power is turned off and the reset state is set, the information display is canceled.

When the device of the present invention is used to input and display high-level image information such as still image information or moving image information, the electrodes have a matrix configuration. That is, the lower electrode has a stripe shape of n lines, and the upper electrode has a stripe shape of m lines so as to be orthogonal to the stripe shape. The region where the lower and upper electrodes intersect each other is n × m pixels. With this configuration, when image information is input, the detection operation is matrix-driven to read the coordinates at which light is input. Further, when displaying image information, the display of image information is controlled by driving the driving circuit in a matrix mode that sweeps signals applied to the lower electrode and the upper electrode. In this case, it is possible to integrate the light detection function and the light emission display function by converting the information about the light input to the light response unit into a light input detection information and a light emission display drive information as a voltage change or a current change. Is desirable. However, it is desirable to reduce the interference between the electric signal used for the light detection operation and the electric signal used for driving the light emitting display so that the element has a sufficient original function.

Here, FIG. 25 shows an example of the light input type EL element having the matrix-structured electrodes. In FIG. 25, the scanning line electrode 11 for hole injection is formed on the substrate 111.
2, photoresponsive portion 113, hole injection layer 114 / light emitting layer 115
A light emitting display portion 117 including an electron injection layer 116 and a data line electrode 118 for electron injection are sequentially formed. Many scanning line electrodes 112 and many data line electrodes 11
8 extend in directions orthogonal to each other and form a so-called simple matrix.

FIG. 26 shows a block diagram of a basic control circuit applied to a display panel having such a matrix structure. When the display panel 110 is viewed in a plan view, the n scanning line electrodes Xi (i = 1 to n) 112 and the m data line electrodes Yj (j = 1 to m) 118 extend in directions orthogonal to each other. There is. The area corresponding to the intersection of the scanning line electrode 112 and the data line electrode 118 becomes one pixel 119, and n × m
Individual pixels are integrated. The control circuit of FIG. 26 includes a drive control logic circuit 120, a scanning line drive circuit 130, an image data register 140, a data line drive / light detection circuit 150,
A light detection output circuit 160 and a light detection control circuit 170,
As will be described in detail below, the light detection function and the light emission display function are integrated at the element level.

First, the operation for displaying an image will be briefly described. The image information to be displayed is preprocessed so as to be suitable for the display method, and the image information of one frame is m data line information on n scanning lines, that is, n × m.
Matrix information (Xi, Yj) (where i = 1
.About.n, j = 1 to m). The light emission display is performed by simultaneously driving the pixels (Xi, Y1 to m) on one scanning line. By sequentially scanning the scanning lines from X1 to Xn, a light emitting display operation on the entire screen is performed and image information for one frame is displayed.

This operation will be described more specifically with reference to FIG. The drive control logic circuit 120 is connected to a circuit for performing data processing related to image information, a clock for driving the entire circuit, and a power source for driving light emission of elements and system driving. The clock signal is divided and sent to each block of the device. The image information is the drive control logic circuit 12
At 0, it is processed as a serial digital signal and sent to the image data register 140. Image data register 14
At 0, the sent serial signal is processed into a parallel signal for each scanning line. Here, the serial signals corresponding to each pixel of the entire screen sent in the form of (Xi, Yj) are (X1, Y1 to m), (X2, Y1 to m),
As shown in (X3, Y1 to m), ..., (Xn, Y1 to m), all pixels on one scanning line are processed into a parallel signal as one set. The information corresponding to the entire screen of one frame is the number of scanning lines, that is, n sets of parallel signals. The image information processed into a parallel signal in this way is sent as a drive signal for the data line drive / light detection circuit 150.

The data line driving / light detecting circuit 150 includes a switching element for controlling connection with a power source in order to realize the light emitting display function of the display panel 110, and the display panel 11.
The function for detecting the optical input to 0 is integrated in a circuit. The data line driving / light detecting circuit 150 outputs the image signal for each pixel sent from the image data register 140 in parallel, and simultaneously drives each pixel on one scanning line selected by the scanning line driving circuit 130. As a result, light emission display is performed in the pixels corresponding to one scanning line. In order to display the image information of one frame on the entire screen, the above-described operation is performed for all scanning lines. That is, the scanning line driving circuit 130 having a shift register function sequentially selects n scanning line electrodes 112,
The image information of the entire screen can be displayed by sending parallel information corresponding to the pixel signal on the selected scanning line from the data line driving / photodetection circuit 150 to the m pixels. By continuing the above operation, continuous frame information can be displayed on the screen at any time.

Next, the light detection operation will be described. One scanning line electrode (Xi selected by the scanning line driving circuit 130
When light is input to each pixel (Xi, Y1 to m) of 1), an electric signal (light detection signal) is generated in that pixel. The light detection signal corresponding to m pixels is the data line 1
It is sent to the data line drive / photodetection circuit 150 via 18, and further sent to the photodetection output circuit 160 as a parallel signal. In the photodetection output circuit 160, the photodetection signals sent in parallel are converted into serial signals and further sent to the photodetection control circuit 170. Further, the scanning line driving circuit 130 causes the scanning line electrodes 11 on the display panel 110
By sequentially selecting 2, it is possible to capture information on the pattern of light input on the display panel 110. The light detection signal sent to the light detection control circuit 170 is
It is sent to the drive control logic circuit 120 as image information and used as a drive signal for the element. The light input information detected in this way can be output as image information.
Further, if necessary, the light detection control circuit 170 can output the light detection information to another information processing system.

In the control circuit in which the light detection function and the light emission display function are integrated as described above, the light response function used in the EL element and the timing at which the light emission display function and the light detection function are expressed are determined according to the characteristics. Specifically, various circuit configurations are possible. For example, in the case of the type in which a photo-responsive portion detects a photo-current or a photo-electromotive force, since light-emission display and light detection are performed simultaneously, light-emission display of pixels (Xi, Y 1 to m) for each scanning line. The operation and the light detection operation are performed. Further, when the light emitting display function and the light detecting function are alternately exhibited (reflex type), the light emitting display and the light detecting may be alternately performed for each scanning line, or one frame of image information is light emitting displayed. After that, light detection may be performed on all pixels or a specific range of pixels.

The EL element and the control circuit may be formed on the same substrate or may be formed on different substrates. Further, various circuits forming the control circuit may be formed on the same substrate or may be formed on different substrates.

[0053]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows an element of this example. On a polyester resin substrate 11 having a thickness of 100 μm, a film thickness of 500 n made of ITO
m hole injecting electrode 12, and trinitrofluorenone (TNF) -doped polyvinylcarbazole (PV
The photoresponsive portion 13 of K) having a film thickness of 300 nm is sequentially formed. On the photo-responsive part 13, a hole injection layer 14 made of tetrakis (diphenylaminophenyl) ethane and having a thickness of 100 nm, and a film thickness of 30 n made of tris (8-hydroxyquinolino) aluminum (hereinafter referred to as Alq ₃ ).
m light emitting layer 15 and a film thickness of 1,3,5-tri (4-t-butylphenyloxadiazolyl) benzene 1
The electron injection layer 16 having a thickness of 00 nm is sequentially formed. The hole injection layer 14, the light emitting layer 15, and the electron injection layer 16 form a light emitting display unit 17. Light emitting display unit 17
An electron injection electrode 18 made of Mg—Ag and having a film thickness of 200 nm is formed on the electron injection layer 16 constituting the above, and a protective film 19 made of polyethylene resin is further formed thereon.

The TNF-doped PVK used in the photoresponsive section 13 has a property that the resistivity ρ for holes changes greatly when it absorbs light in a predetermined wavelength range emitted from a semiconductor LED or a semiconductor laser. . In particular,
ρ is 10 ⁻¹⁰ Ω · cm in the dark, but increases to 10 ⁻⁵ to 10 ⁻⁴ Ω · cm during light irradiation.

The bonding state of each layer constituting the light emitting display section 17 is as follows. An electron injecting bond is formed between the electron injecting electrode 18 and the electron injecting layer 16. A junction having an electron injecting property and a hole blocking property is formed between the electron injecting layer 16 and the light emitting layer 15. On the other hand, a hole injecting junction is formed between the hole injecting electrode 12 and the hole injecting layer 14. A junction having a hole injecting property and an electron blocking property is formed between the hole injecting layer 14 and the light emitting layer 15.

The operation of this element will be described in time series with reference to FIGS. FIG. 2A is a diagram showing changes in voltage applied between electrodes, FIG. 2B is a diagram showing changes in current flowing between electrodes, and FIG. 2C is a diagram showing changes in light emission luminance.

Electron injection electrode 18 and hole injection electrode 12
No light emission occurs when no voltage is applied between and. Here, the electron injection electrode 18 and the hole injection electrode 12
So that the electron injection electrode 18 becomes negative between
A bias voltage of V is applied (forward bias). When the light responsive unit 13 is not irradiated with light, the light responsive unit 13
Since the electric conductivity of is low, holes are hardly injected from the hole injection electrode 12 to the photoresponsive portion 13. Therefore, an effective voltage is not applied to the light emitting display unit 17, and light emission does not occur. On the other hand, when the light responsive portion 13 is irradiated with strong light (light input ON), the electrical conductivity of the light responsive portion 13 increases, and holes are injected from the hole injection electrode 12 into the light responsive portion 13. Therefore, a voltage of about 10 V, which is almost equal to the voltage applied between the electrodes, is applied to the light emitting display section 17. As a result, electrons are injected from the electron injection electrode 18 into the light emitting layer 15 through the electron injection layer 16, and holes are emitted from the hole injection electrode 12 to the photoresponsive portion 13.
And holes are injected into the light emitting layer 15 through the hole injection layer 14, and in the light emitting layer 15, electrons and holes are recombined to emit light.

Further, if the circuit configuration as shown in FIG. 3 is adopted, it is possible to detect the presence / absence of light input by utilizing the fact that the current density flowing between the electrodes changes. As shown in FIG. 3, the drive unit 20 has a configuration in which a drive circuit 21 and a detection circuit 22 are connected in series. The detection circuit consists of a current amplifier and a level comparator. Now
When the current density increases to such an extent that luminescence display occurs, the output voltage of the current amplifier that constitutes the detection circuit 22 increases. When this output voltage exceeds the threshold value set by the level comparator, the output of the level comparator is turned on, and it can be electrically detected that light is emitted. Therefore, if the electrode matrix is configured, the address information of the coordinate position where the light is input can be obtained using such a circuit.

Example 2 FIG. 4 shows an element of this example. IT on the glass substrate 31
The hole injecting electrode 32 made of O is patterned and formed. On the hole injecting electrode 32, a hole injection layer 33 made of the triphenylamine derivative (TPA-2) shown in Chemical formula 1 and having a film thickness of 50 nm, and a tetraphenylpentadiene derivative (TPCyP) shown in the chemical formula 2 are formed. A light emitting layer 34 with a film thickness of 50 nm and an electron injection layer 35 with a film thickness of 30 nm made of a p-diphenoquinone derivative (DPQ-1) shown in Chemical formula 3 are sequentially laminated. The light emitting display unit 36 is formed by these three layers of organic thin films. On the light emitting display section 36, a photo-responsive section 37 made of Cu / TCNQ and having a film thickness of 100 nm is formed by a vacuum vapor deposition method. Further, an electron injection electrode 38 made of semitransparent Al is formed on the photoresponsive portion 37.

[0061]

[Chemical 1]

[0062]

[Chemical 2]

[0063]

[Chemical 3] A DC bias of 12 V was applied to this device, but no light emission was observed. Furthermore, when a 12 V DC bias was applied to this device, laser light having a wavelength of 514.5 nm, a spot size of 2 μm, and an intensity of 5 μW or more was irradiated from an Ar ion laser, and emission of bluish green was observed from the light emitting layer 34. . Thus, it was confirmed that the light emitting operation occurs by inputting the light having the intensity higher than the threshold value.

Example 3 The structure is almost the same as that of the element of Example 2 shown in FIG. 4, but the light emitting layer 34 is made of Alq ₃ (thickness 30 nm),
The photoresponsive portion 37 is made of a perylene-3,4,9,10-tetracarboxylic acid diimide derivative (film thickness 100 nm) represented by Chemical Formula 4 formed by a vacuum deposition method, and the electron injection electrode 38 is a semitransparent Mg. A device made of -Ag was produced.

[0065]

[Chemical 4] Using the perylene-3,4,9,10-tetracarboxylic acid diimide derivative that constitutes the photoresponsive part, p-Si \ Si
A MOS type device having a structure of O ₂ \ organic thin film \ metal electrode was prepared and a displacement current characteristic was measured by applying a triangular wave voltage. As a result, it was confirmed that electron injection from the metal electrode into the organic thin film occurred only after irradiation with light of 450 to 580 nm.

With a direct current bias of 10 V applied to this element, a wavelength of 488 nm was emitted from an Ar ion laser.
When a laser beam having a spot size of 2 μm and an intensity of 5 μW was irradiated, emission having a peak at a wavelength of 530 nm was observed. On the other hand, no light emission was observed from the laser non-irradiated part.

Example 4 FIG. 5 shows an element of this example. A hole injection electrode 42 made of ITO is patterned and formed on a polycarbonate film substrate 41. On the hole injection electrode 42, a hole injection layer 43 made of a triphenylamine derivative (TPA-2) with a film thickness of 50 nm, a light emitting layer 44 made of Alq _{3 with} a film thickness of 30 nm, a p-diphenoquinone derivative (DPQ-). The electron injection layer 45 composed of 1) and having a film thickness of 30 nm
Are sequentially formed. The light emitting display section 46 is formed of these three layers of organic thin films. This light emitting display unit 46
A lower photo-responsive portion 47 made of copper / tetracyanonaphthoquinodimethane complex (Cu / TNAP) having a film thickness of 30 nm is formed thereon by a vacuum vapor deposition method. An electron injection electrode 48 made of semitransparent Al is patterned and formed on the lower layer photoresponsive portion 47. Furthermore, a film thickness of 140 nm formed of a p-phenylenediamine derivative represented by Chemical formula 5, which is an organic photochromic material, by a vacuum deposition method.
The upper layer photoresponsive portion 49 is formed.

[0068]

[Chemical 5] The Cu / TNAP forming the lower layer optical response part 47 is 488n.
It has an absorption peak near m. On the other hand, the upper layer optical response section 49
The absorption characteristics of the p-phenylenediamine derivative constituting the above are as follows. 400n when not illuminated
It shows a large absorption tail from near m to 500 nm. 40
When it continues to irradiate with 0 nm light, it changes to an absorption characteristic showing a large absorption peak at 550 to 600 nm and changes to 488 nm.
Absorption in the vicinity is significantly reduced.

With respect to the organic compound used in the photoresponsive portion, a MOS type device having a structure of p-Si \ SiO ₂ \ organic thin film \ metal electrode was prepared and the displacement current characteristics were examined. When only Cu.TNAP is used as the organic thin film, when a light of 488 nm is irradiated with a negative bias applied, a large displacement current change due to carrier injection occurs. However, when a laminate of Cu.TNAP and a p-phenylenediamine derivative is used as the organic thin film, a change in displacement current is not observed by irradiation with light of 488 nm even when a positive or negative bias is applied, and the organic thin film and SiO Only the constant current estimated from the combined capacity with the _two membranes flowed. On the other hand, the film having the two-layer structure is irradiated with the first light of 400 nm, and the irradiated portion of the first light is 488 nm.
In the case of irradiating the second light of (1), carrier injection characteristics similar to those of the Cu / TNAP single layer were exhibited.

From these facts, when the film of the p-phenylenediamine derivative is irradiated with the first and second lights at the same time,
It was found that the absorption characteristics of the first light were changed and the second light was not absorbed, and as a result, the second light reached Cu.TNAP and Cu.TNAP was activated.

When the device of this example was irradiated with the first and second lights simultaneously while a DC bias was applied, yellowish green light was emitted only from the irradiation part. On the other hand, when the light having a wavelength of 580 nm was irradiated, the light emission did not occur even when the second light was irradiated.

Example 5 FIG. 6 shows an element of this example. IT on the glass substrate 51
A hole injection electrode 52 made of O is formed. On this hole injecting electrode 52, a hole injecting layer 53 made of a triphenylamine derivative and having a film thickness of 50 nm, and a light emitting layer 54 made of Alq ₃ and having a film thickness of 50 nm are sequentially formed. The light emitting display section 55 is formed by these two layers of organic thin films. Cu / TNA is displayed on the light emitting display 55.
A lower photoresponsive portion 56 made of P having a thickness of 50 nm, an electron injection electrode 57 made of chromium, and a thickness of 10 made of azobenzene cholesteryl which is an organic photochromic material.
An upper layer photoresponsive portion 58 of 0 nm is sequentially formed. Cu
-TNAP has the property of generating carriers upon irradiation with light. Azobenzene cholesteryl has the characteristic that the transmittance changes with the irradiation of light.

When a 800-nm laser beam was irradiated in a pattern from a semiconductor laser while applying a DC bias of 15 V to this device, yellow-green light emission was observed at the locus. On the other hand, no light emission phenomenon was observed in the non-irradiated area. Next, after irradiating a laser beam of 730 nm from another semiconductor laser, 800 n
When irradiated with m laser light, no light emission was observed in both the irradiated and unirradiated parts. Furthermore, after irradiating laser light of 860 nm from another semiconductor laser, 800
When irradiated with a laser beam of nm, emission was observed again.

That is, in the device of this embodiment, 860n
Information can be written with a laser beam of m, and an operation corresponding to input information can be caused by using a laser beam of 800 nm. On the other hand, the input information can be erased by irradiating with light of 730 nm.

Example 6 FIG. 7 shows an element of this example. I on the glass substrate 61
A hole injecting electrode 62 made of TO is patterned and formed. On top of this, a hole injection layer 6 made of a triphenylamine derivative (TPA-2) and having a film thickness of 50 nm.
3, a light emitting layer 64 made of Alq ₃ and having a thickness of 50 nm, p−
Film thickness 30 made of diphenoquinone derivative (DPQ-1)
nm electron injection layer 65 is sequentially formed. The light emitting display section 66 is formed by these three layers of organic thin films. On the light emitting display section 66, a first photoresponsive section 67 made of Cu.TCNQ, a second photoresponsive section 68 made of tetra (4-pyridyl) porphyrin, and a perylene-3, each having a film thickness of 50 nm, were formed. The third photoresponsive portion 69 made of a 4,9,10-tetracarboxylic acid diimide derivative is
It is formed by patterning as a pixel of 400 μm × 400 μm. As shown in FIG. 8, an electron injection electrode 70 made of semitransparent Al is formed on each pixel.

When a direct current voltage of 20 V was applied to this element, three lights (λ ₁ =
Irradiation at 510 nm, λ ₂ = 650 nm, λ ₃ = 900 nm). When irradiated with light of λ ₁ , the first and third
Light emission was observed under the pixel patterns of the photo-responsive parts 67 and 69. When the light of λ ₂ was irradiated, light emission was observed under the pixel patterns of the first and second photoresponsive parts 67 and 68. When the light of λ ₃ is irradiated, the first light response unit 6
Light emission was observed only under the 7 pixel pattern. Thus, it was confirmed that multiple inputs can be realized.

Embodiment 7 FIG. 9 shows a reflex type element in this embodiment.
IT on the polyester resin substrate 71 with a thickness of 100 μm
A hole injection electrode 72 made of O and having a film thickness of 500 nm is formed. On the hole injecting electrode 72, a hole injecting layer 73 made of Cu phthalocyanine and having a film thickness of 50 nm and also serving as a photoresponsive portion is formed. Cu phthalocyanine is
It has a property of generating electrons and holes when absorbing light. Furthermore, tetrakis (diphenylaminophenyl)
100 nm thick hole injection layer 74 made of ethane, Al
a light emitting layer 75 made of q ₃ and having a film thickness of 30 nm;
5-tri (4-t-butylphenyloxadiazolyl)
An electron injection layer 76 made of benzene and having a thickness of 100 nm is sequentially formed. The hole injection layer 73, the hole injection layer 74, the light emitting layer 75, and the electron injection layer 7 which also serve as these photoresponsive parts.
6 constitutes a light emitting display section 77. An electron injection electrode 78 made of Mg—Ag and having a film thickness of 200 nm is formed on the electron injection layer 76 which constitutes the light emitting display unit 77. Further, a protective film 79 made of polyethylene is formed on the electron injection electrode 78.

The bonding state of each layer constituting the light emitting display section 77 is as follows. An electron injecting junction is formed between the electron injecting electrode 78 and the electron injecting layer 76. A junction having an electron injection property and a hole blocking property is formed between the electron injection layer 76 and the light emitting layer 75. On the other hand, a hole injecting junction is formed between the hole injecting electrode 72 and the hole injecting layer 74. A junction having a hole injecting property and an electron blocking property is formed between the hole injecting layer 74 and the light emitting layer 75.

Electron injection electrode 78 becomes negative in this element
When a voltage above a certain value is applied, a current flows,
The intensity of light emission is proportional to the current. like this
The voltage at which current flows with forward bias is V^ON, Current flows
No voltage V^OFFAnd V ^ONAnd V^OFFApplied voltage between
By controlling the pressure, it is possible to control on / off of the light emitting display.
Now, as shown in FIG. 10 (a), when the light is input, it turns on.
Organic thin film that acts as a photoresponsive section in proportion to the intensity of light
Electrons and holes are formed inside (the hole injection layer 73 that also serves as the photoresponsive portion).
And occur. At this time, as shown in FIG.
When a reverse bias is applied, the photocurrent flows to the outside.
It Therefore, when the reverse bias is applied, the photocurrent is detected.
By doing so, it is possible to determine whether the optical input is on or off.

The device of this embodiment is provided with a drive section for detecting light input and causing it to emit light. This drive unit will be described with reference to FIG. The drive unit includes a drive circuit that controls a light emitting operation and a detection circuit that detects an optical input. The oscillator 101 outputs an AC square wave pulse voltage having a predetermined oscillation frequency. The output of the oscillator 101 is input to the drive pulse amplifier 102, and the gain variable differential amplifier 103
Can output two pulses of V ^ON and V ^OFF .
Normally, a drive pulse voltage of V ^OFF is output. The output of the oscillator 101, the phase is input to the detection pulse amplifier 105 is offset 180 ° by an inverter 104, the output voltage is amplified so that + V ^P. The drive pulse voltage and the detection pulse voltage are input to the − side and the + side of the drive amplifier 106, respectively, and the waveforms are synthesized. The drive amplifier 106 is connected to the hole injection electrode 72 of the light input type organic EL element of the present embodiment via a detection circuit connected in series with the drive amplifier 106. The detection circuit includes a diode circuit 107, a current amplifier 108, and a level comparator 109. The drive current from the drive amplifier 106 flows to the element through the diode circuit 107,
The photovoltaic current generated in the element flows to the detection circuit via the diode circuit 107. When light is input to the element and a photocurrent flows, the output voltage of the current amplifier 108 changes. The output voltage is the threshold value V set by the level comparator 109.
_{When th} is exceeded, the output of the level comparator 109 is turned on. As a result, the amplification factor of the variable gain differential amplifier 103 increases, the output level of the drive pulse changes from V ^OFF to V ^ON , and light emission occurs. The voltage-current change at this time is shown in FIG.

The operation of the device of this embodiment will be described in time series with reference to FIG. Between the electrodes of the element, V ^OFF and -V
^P pulses are applied alternately. At this time, no current flows through the element and no light emission occurs. When the element is exposed to light,
Photoelectromotive current flows from the element during the pulse of -V ^P. This photocurrent is detected by the detection circuit, and the output voltage level of the drive circuit is changed to V ^ON . Then, since a forward current flows through the element during the V ^ON pulse, light emission occurs. While the optical input continues, a photocurrent is detected every −V ^P pulse and the drive pulse voltage is maintained at V ^ON . When the light input is turned off, the drive pulse voltage returns to V ^OFF and the light emission is stopped.

If a flip-flop is inserted between the detection circuit and the variable gain differential amplifier that form the drive unit, even if the light input is turned off after the light input is turned on and light emission occurs. The light emission continues and the input information continues to be displayed. This display is stopped by giving a reset signal to the flip-flop or inputting light again.

Example 8 The element of this example has substantially the same structure as the element of Example 2 shown in FIG. However, the following materials are used for each organic thin film. That is, the hole injection layer 33 is an organic molecule represented by Chemical formula 6, the light emitting layer 34 is Alq ₃ , the electron injection layer 35 is an oxadiazole derivative, and the photoresponsive portion 3
7 is composed of copper phthalocyanine (CuPc) doped with dicyanodichloroquinodimethane (DDQ).
The photoresponsive portion 37 is produced by co-evaporating CuPc and DDQ by controlling the molecular beam density by a vacuum vapor deposition method, and DDQ is doped to a concentration of -10 ¹⁸ / cm ³ .

[0084]

[Chemical 6] This element operates according to the principle shown in FIG. No light emission was observed simply by applying a voltage of 15 V to this device. Next, when a light of 650 nm was irradiated from a red semiconductor laser with a voltage of 15 V applied to this device, yellow-green light emission from Alq ₃ was observed. Also,
The light emission stopped when the light irradiation was stopped.

Next, in the following examples, the light input type organic EL device according to the present invention in which the electrodes have a matrix structure will be described.

Example 9 The reflex type element described in Example 7 performs light emission display with forward bias and detects a photocurrent with reverse bias, so that the polarities of the voltages applied during two operations are used. Need to be reversed. In this embodiment, matrix driving is performed while switching the inputs from two power supplies by clocking to change the polarity of the applied voltage.

FIG. 27 is a circuit diagram of a data line driving / photodetecting circuit (150 in FIG. 26) used in the device of this embodiment. In this data line drive circuit / photo detection circuit,
A switching element 201 for driving a light emitting display and a switching element 202 for detecting light are connected to each data line electrode 200. In the switching element 201 for driving the light emitting display, the source is connected to the driving power source, the gate is connected to the output of the data line address signal 206, and the data line address sent from the image data register (140 in FIG. 26). A drive current is sent to the data line electrode 200 connected to the drain according to the signal 206. The switching element 202 for light detection has a source connected to the data line electrode 200 and a drain connected to the detection signal amplifier circuit 20.
It is connected to the driving power source through 3. Further, the switching is performed by the light detection signal 205 connected to the gate electrode. The light emission display and the light detection are performed at different timings as described below in order to avoid signal interference.

The light emitting display operation is performed by the data line address signal 2
06, the switching element 201 is turned on, and the data line input signal corresponding to the pixel on one scanning line electrode stored in the image data register (140) is sent. At this time, the driving power supply is switched to the power supply of the positive bias side output. Since the switching element 202 for light detection is in the off state, no current flows into the optical input signal amplification circuit 203 and the level comparator 204. Although the scanning lines are omitted in the figure, the pixels (Xi, Y 1 to m) on the scanning line Xi selected by the scanning line driving circuit (130 in FIG. 26) are luminescently displayed. Full screen emissive display is achieved by shifting the scan lines from X1 to Xn.

The light detecting operation is performed after the light emitting display operation. After the output of the data line address signal 206 is finished and the switching element 201 for driving the light emitting display is turned off, the drive voltage is inverted by switching to the power source on the negative bias side. At the same time, the light detection signal 205 is input, and the light detection switching element 2 is input.
02 is turned on, and the detection operation is performed. By shifting the scanning line from X1 to Xn as in the case of the light emitting display operation, the light input on the entire screen is detected. When the corresponding pixel has an optical input, the detected photocurrent is transmitted through the switching element 202 to the optical input signal amplifier circuit 203.
Sent to. The optical input signal amplified by the amplifier circuit 203 is compared with the reference signal V _{th by the} level comparator 204,
When the light input is confirmed, the light input ON signal 207 is emitted. The light input ON signal 207 is sent to the light detection output circuit (160 in FIG. 26), subjected to serial signal processing, and sent to the light detection control circuit (170 in FIG. 26). The light input information is sent from the light detection control circuit (170) to the drive control logic (120 in FIG. 26) to be used for light emission display output, and is also output to other information equipment.

It should be noted that one power supply circuit may be provided for each column. In this case, it is possible to simplify the portions of the switching elements for driving and for detecting light. Regarding the above-mentioned operation timing, the light detection of the entire screen may be performed after the light emission display of one frame, or the light detection on the scanning line may be performed immediately after the light emission display of one scanning line.

Example 10 The element described in Example 1 performs a light emitting display operation by changing the light emission threshold voltage of the element due to light input. On the other hand, when there is no light input, no current flows at the applied voltage and light emission does not occur. In this case, the light input can be detected by detecting the injection current to the element accompanying the light emission accompanying the light input. That is, in such an element, matrix driving is performed while simultaneously performing the light detection operation and the light emission display operation.

FIG. 28 is a circuit diagram of the data line driving / photodetecting circuit (150) used in the device of this embodiment. In the switching element 211 for driving the light emitting display, the drain is connected to the data line electrode 200, and the source is connected to the driving power source via the current detection / amplification circuit 212. Switching is performed by the data line address signal 215 connected to the gate. When light-emission display is performed in accordance with light input, the current injected into the element is the current detection / amplification circuit 2
Observed by 12. This injection current value is
After being amplified by the amplifier circuit 212, the level comparator 2
13 is compared and judged with the reference signal V _th, and the light detection output circuit (160) is provided in parallel as the light input ON signal 214.
Sent to. The input parallel signal is subjected to serial signal processing by the photodetection output circuit (160) and sent to the photodetection control circuit (170).

Embodiment 11 An example of matrix driving of the element having the multiple input function described in Embodiment 6 will be described. In the device shown in FIG. 7, the photoresponsive part is Cu.TCNQ (first photoresponsive part), tetra (4-pyridyl) porphyrin (second photoresponsive part) and perylene-3,4,9,10-tetra. It is composed of three regions of a carboxylic acid diimide derivative (third photoresponsive portion), and λ ₁ = 510 nm, λ ₂ = 650 nm, and λ, respectively, with a voltage of 20 V being applied.
_When the light emitting display operation is performed by irradiating three kinds of light of ₃ = 900 nm, the injection current to the element changes. In this embodiment, matrix driving is performed while utilizing this phenomenon to determine the type of irradiation light.

FIG. 29 is a circuit diagram of the data line driving / photodetecting circuit (150) used in the device of this embodiment. In the switching element 221 for driving the light emitting display, the drain is connected to the data line electrode 200, and the source is connected to the driving power source via the current detection / amplification circuit 222. Switching is performed by the data line address signal 225 connected to the gate. When light emission display is performed in response to an optical input of any one of the three types of light, the current detection / amplification circuit 222 observes the injection current to the element corresponding to the irradiation light. This injected current value is the current detection / amplification circuit 2
After being amplified by 22, the A / D converter 223 sends it as a digital optical input ON signal 224 to the photodetection output circuit (160) in parallel. The input digital parallel signal is converted into a digital serial signal by the photodetection output circuit (160), and the photodetection control circuit (170).
Sent to. The input digital signal is judged by the photodetection control circuit (170) as the amount of current flowing through the element,
It is possible to determine the type of irradiation light. In this way, it becomes possible to judge the multiple light input and the irradiation light in the display panel.

Example 12 An example of matrix-driving an element having a non-volatile memory function in which the photoconductivity of the photoresponsive portion of the element is changed to a low resistance state by optical input and the low resistance state is held. explain. In the present embodiment, the photoresponsive portion has Cu whose conductivity decreases not only by light irradiation but also by voltage application.
-The element which consists of TCNQ is used.

FIG. 30 shows a circuit diagram of the scanning line drive circuit (130 in FIG. 26) used in the device of this embodiment, and FIG. 31 shows a circuit diagram of the data line drive / photodetection circuit (150).

First, the light input operation will be described. When performing optical input, all scanning line switching elements 30
1, and all the data line switching elements 231 are turned on, and a low applied voltage (hereinafter, V ₁ ) is applied to all pixels from the driving power source. V ₁ is a voltage that can drive the pixel to emit light when the photoresponsive portion is in a low resistance state, and is set to 10 V in this embodiment. When light is input in this state, the corresponding photoresponsive portion undergoes a phase transition to a low resistance state, and as a result, a light emitting display operation associated with the application of V ₁ is exhibited. The light emitting display operation continues as long as the voltage V ₁ is applied. Further, since the memory function for light input is non-volatile, it continues even if the application of V ₁ is stopped. Unless the memory is erased, by applying V ₁ again, the luminescence display of the stored information can be performed.

Next, the light detection operation will be described. Photodetection can be realized by addressing each pixel with an applied voltage V ₁ . Addressing is performed by the scanning line address signal 30 from the scanning line driving circuit (130 in FIG. 26).
5, one scanning line electrode (Xi) is selected, and a voltage is simultaneously applied to the pixels (Xi, Y 1 to m) on the selected scanning line electrode by using the data line driving circuit (150 in FIG. 26). By doing. By sequentially selecting the scanning line electrodes 300, it is possible to address all the pixels of the display panel. As described above, since the photo-responsive portion is in the low resistance state in the pixel which is optically input, a current flows through the pixel as light is emitted. This current is detected by the current detection / amplification circuit 232 and compared with V _th by the level comparator 233. When the light emission of the pixel is determined as a result of this comparison, the light input ON signal 237 is output in parallel to the light detection output circuit (160 in FIG. 26). The optical input ON signal 237 input in parallel is converted into a serial signal by the photodetection output circuit (160), and the photodetection control circuit (FIG. 26).
170). These pieces of information are accumulated in the light detection control circuit (170) and used for image display or output to an external device.

Next, the image display operation will be described. Since the photo-responsive part of the element is in a high resistance state, a voltage (V ₂ ) higher than V ₁ is required to make the element emit light. In this embodiment, V ₂ is set to 25 volts.
For image display, V ₂ is used for the pixels of the panel to sequentially select the scan line electrodes (300) by the scan electrode drive circuit (130), and at the same time, select the scan electrode (300) by the data line drive circuit (150). 300) by adding an image signal to the upper pixel. Once you write the image information,
Since the photoresponsive portion of the pixel in the light emitting display state is in the low resistance state, the light emitting display operation can be maintained by continuously applying V ₁ to all the pixels.

Finally, the erase operation of the memory information will be described. For the erase operation, energy capable of erasing the memory effect of the photoresponsive portion of the device may be applied. In this embodiment, memory information is erased by applying a reverse bias. Specifically, the scanning line driving circuit (130) is provided with an erasing switching element 302 to input an erasing signal 303, and the data line driving / photodetecting circuit (150) is provided with an erasing switching element 234. The erase signal 236 is input. By driving these switching elements, the reverse bias is applied to all the pixels, and all the image information stored in the memory is erased. Note that light having an erasing effect may be emitted as a signal for erasing.

As described above, since the EL element according to this embodiment has a memory function, operations such as image input, light detection, and memory erasing can be performed at arbitrary timings, and moving image display and various image display can be performed. Will be possible.

Example 13 An example will be described in which an element provided with electrodes corresponding to a plurality of organic thin film regions forming a photoresponsive section capable of multiple inputs is matrix-driven.

FIG. 32 shows an element used in this embodiment. On a glass substrate 351, a hole injection electrode (scan line electrode) 352 made of ITO is formed in a stripe pattern. On this, a hole injection layer 353 made of a triphenylamine derivative, a light emitting layer 354 made of Alq ₃ , and an electron injection layer 355 made of an oxadiazole derivative are sequentially formed. The light emitting display portion 356 is formed by these three layers of organic thin films. On the light emitting display portion 356, a red light responsive portion 357 made of a carbazine derivative and a coumarin type dye (coumarin 334;
2,3,5,6-1H, 4H-tetrahydro-9-acetylquinolizino- <9,9a, l-gh>coumarin; coumarin 521) is used as a blue light responsive portion 358 for hole injection electrodes (scanning). (Line electrode) 352 and is patterned in a stripe shape so as to be orthogonal to the line electrode 352.
Electron injection electrodes (data line electrodes) 359 and 360 made of Mg-Ag are formed in a pattern corresponding to 57 and 358, respectively. Light (red and blue) is input from the glass substrate 351 side, and the light emitting display portion 356 is green 1
Can emit color.

FIG. 33 shows a display panel 35 including this element.
0 is a plan view and FIG. 34 is a plan view in which pixels of this display panel are enlarged. As shown in these figures, m scanning line electrodes 352 and 2n data line electrodes 359, 3 are provided.
By 60, m × n pixels are formed. Also,
Odd and even data line electrodes 359, 360
Correspond to the red and blue photoresponsive parts 357 and 358, respectively.

FIG. 35 shows a circuit diagram of a data line driving circuit (380 in FIG. 33) used in the element of this embodiment. In this case, both the blue response part and the red response part are matrix-driven as independent pixels. The switching of the switching element 401 for driving the light emitting display is performed by the data line address signal 405 similarly to the circuits of the above-described embodiments. When light emission display is performed in accordance with light input, the current detection / amplification circuit 402 observes the current injected into the element. The injected current value is amplified by the current detection / amplification circuit 402, and then the input state is determined by the identification circuit 403. The output of the identification circuit 403 becomes a 2-bit digital signal. That is, 00 when there is no input, 01 when red input, 10 when blue input, 11 when simultaneous input
Becomes This signal is sent to the color discriminating circuit 404, and further sent to the circuit in the subsequent stage in the same manner as the circuits of the above-described embodiments. In this way, it is possible to matrix-drive the light emitting display by the multiple input of two colors. Alternatively, a method may be used in which the signals from the blue pixel and the red pixel are sent to the information device as they are, and the information device side determines whether blue or red by software according to the data address.

In many cases, two kinds of materials used for the photoresponsive portion have their light absorption spectra partially overlap with each other. For example, in response to not only the blue light response section but also the red light response section to the blue light input, green light emission occurs in each region, but to the red light input, only the red light response section responds. An example is considered in which green light emission occurs only in the region. In this case, a circuit configuration may be adopted in which the red light input is judged and the region which was in the light emitting state by the blue light input is erased first. That is, after red light input,
The drive for the pixel is instantly turned off so that the display is erased. In this way, it is possible to perform the write operation that makes the best use of the characteristics of multiple input such as blue input and red erasure.

Example 14 An example of an element having the same element structure as that of Example 13 but capable of discriminating the intermediate color input light will be described. This device has a coumarin-based dye (coumarin 153;
2,3,5,6-1H-tetrahydro-8-trifluoromethylquinolizino- <9,9a, l-gh> coumarin), and the device of FIG. 32 except that copper phthalocyanine was used in the red light responsive part. It has a similar structure. FIG. 36 shows the light absorption spectra of these materials. As shown in this figure, these dyes have absorption over a wide wavelength range.

In such an element, a photoexcitation current is generated only in one of the two photoresponsive sections with respect to a blue or red light input. However, for green or yellow light that is an intermediate color, a photoexcitation current is simultaneously generated in both of the two photoresponsive parts.

FIG. 37 is a circuit diagram of the scanning line drive circuit (380 in FIG. 33) used in the device of this embodiment. The switching of the switching element 411 for driving the light emitting display is performed by the data line address signal 415. When light-emission display is performed in response to optical input, the current injected into the element is observed by the current detection / amplification circuit 412, amplified, and then sent to the division circuit 413. In this division circuit 413, the current value of the light emitting display section corresponding to the red light response section is divided by the current value of the light emitting display section corresponding to the blue light response section. FIG. 38 shows the relationship between the wavelength of input light and the output of the division circuit 413. This output is sent to the A / D converter 414 and further sent to the circuit in the subsequent stage. In this way, almost all the input light in the visible range can be discriminated.

Further, by increasing the types of the photo-responsive parts, the accuracy of recognizing the intermediate color can be improved. For example, in addition to the above configuration, a region of the photo-responsive portion that mainly responds to green is formed. Then, matrix driving is performed by a scanning line driving circuit as shown in FIG. in this case,
Three current detection / amplification circuits 422 are provided corresponding to the light response parts of each color of RGB, and two color discrimination circuits 423 are provided on the red light response part side and the blue light response part side. Then, the current generated in the light emitting display section corresponding to the green light response section is amplified by the current detection / amplification circuit 422 and then sent to the two color discrimination circuits 423 via the optical input signal division circuit 426. In such a circuit configuration, as shown in FIG.
Although the light detection process is slightly more complicated than in the above case, the accuracy of recognizing the intermediate color is improved. Furthermore, by selecting the material used for the optical response section and adjusting the amplification factor of the optical input detection / amplification circuit,
The ability to select intermediate colors can be improved.

Example 15 An element provided with three photo-responsive parts responding to the light of three colors of RGB and three light-emitting display parts respectively emitting the colors of RGB corresponding to the photo-responsive parts was matrix-driven. An example of enabling multicolor input / multicolor display will be described.

In the light emitting display section of this device, a hole injecting layer made of a triphenylamine derivative is provided in common to the three light emitting display sections on a hole injecting electrode on a glass substrate, and a perylene derivative is formed thereon. A red light emitting layer made of Alq ₃ , a green light emitting layer made of Alq ₃ , and a blue light emitting layer made of pentaphenylcyclopentadiene are patterned and provided, and an electron injection layer made of an oxadiazole derivative is provided on the three light emitting display portions. It is provided in common. On top of that, a coumarin-based pigment (coumarin 334; 2, 3, 5, 6
-1H, 4H-Tetrahydro-9-acetylquinolizino- <9,9a, l-gh>coumarin; coumarin 521)
And a green light responsive portion made of a phenoxazine derivative, and a red light responsive portion made of a carbazine derivative are patterned and formed. Further, an electron injection electrode (data line electrode) made of Mg-Ag corresponding to each photoresponsive portion is patterned and formed thereon. The patterns of the light response portion and the light emitting display portion correspond so that the input light and the emitted light have the same color. Figure 40
The absorption spectra of three kinds of materials used in the photoresponsive parts of the respective colors are shown in FIG.

In a display panel using such an element,
N scanning line electrodes and 3m data line electrodes are provided. In the data line electrode, for example, the 3i-th electrode is red and 3
The i + 1th corresponds to green and the 3i + 2th corresponds to blue.

FIG. 41 shows a circuit diagram of a data line driving circuit used in the element of this embodiment. This circuit can be regarded as a circuit in which a circuit corresponding to the data line electrode 400G corresponding to green is added, as compared with the circuit in FIG.
In this case, each of the blue, green, and red photoresponsive sections is matrix-driven as an independent pixel. The switching of the switching element 431 for driving the light emitting display is performed by the data line address signal 435. When light-emission display is performed in response to light input, the current injected into the element is observed by the current detection / amplification circuit 432, amplified, and then sent to the color determination circuit 433 driven by the clock signal 436,
Further, the optical input signal 434 is sent to the circuit in the subsequent stage. In this case, a color discrimination circuit may be provided before the color discrimination circuit 433 to perform preprocessing. It is also possible to use a method in which the signal from each pixel is sent to the information device as it is, and blue, green, or red is software-determined according to the data address on the information device side.

In this way, blue light is emitted for blue light input, green light is emitted for green light input, and red light is emitted for red light input. For example, when three colors are simultaneously input, white light is emitted. A display close to full color display can be realized. In addition, each input of RGB is written, erased,
If it is assigned to the reconversion function or the like, it becomes a display element capable of multi-functional input.

However, the organic dye always has absorption even on the short wavelength side from the absorption edge. The above operation is possible when an ideal dye having an absorption intensity on the shorter wavelength side than the main absorption band is extremely small is used in the photoresponsive portion, but this condition may not always be satisfied. For example, all light response parts respond to blue light input, green light response part and red light response part respond to green light input, and only red light response part responds to red light input. Such cases are possible. When such an element is used, the input light color is determined by the timing at which the blue light response portion, the green light response portion, and the red light response portion are sequentially scanned and the output is obtained.

In this case, white light is emitted for blue light input, orange light is emitted for green light input, and red light is emitted for red light input. Therefore, the color of the input light and the color of the light emission display are different. It does not correspond to 1: 1. In order to avoid this, the device structure may have an optical filter function.
Specifically, by adding a function as an optical bandpass filter to the material itself used for the photoresponsive portion, the color of the input light and the color of the light emission display can be made to correspond to each other 1: 1.

[0118]

As described above in detail, according to the present invention, it is possible to input information by light and also to have various functions such as a switching function, a memory function and a multiple input function. An element can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a light input type organic EL element in Example 1 of the present invention.

2A to 2C are characteristic diagrams showing the operation of the device of FIG. 1 in time series.

3 is a circuit diagram showing an optical input detection circuit system in the device of FIG.

FIG. 4 is a cross-sectional view of a light input type organic EL element in Example 2 of the present invention.

FIG. 5 is a sectional view of a light input type organic EL element according to Example 4 of the present invention.

FIG. 6 is a sectional view of a light input type organic EL element according to Example 5 of the present invention.

FIG. 7 is a cross-sectional view of a light input type organic EL element in Example 6 of the present invention.

FIG. 8 is a plan view of the device of FIG.

FIG. 9 is a cross-sectional view of a light input type organic EL element according to Example 7 of the present invention.

10A and 10B are energy band diagrams for explaining the operation when light is applied to the device of FIG. 9 and a reverse bias is applied.

11 is a circuit diagram showing a drive circuit and a detection circuit for detecting an optical input used in the device of FIG.

12 is a characteristic diagram showing a voltage-current relationship in the device of FIG.

13A to 13C are characteristic diagrams showing the operation of the element of FIG. 9 in time series.

FIG. 14 is a cross-sectional view showing a light emitting display section which constitutes an optical input type organic EL element according to the present invention.

15A and 15B are energy band diagrams for explaining the operation principle of the light emitting display section.

FIG. 16 is a characteristic diagram showing a displacement current characteristic of an example of an organic thin film used in a photoresponsive section that constitutes an optical input type organic EL element according to the present invention.

FIG. 17 is a spectrum diagram showing the absorption characteristics of another example of the organic thin film used in the photoresponsive section that constitutes the light-input organic EL element according to the present invention.

FIGS. 18 (a) and 18 (b) are spectrum diagrams showing absorption characteristics of an example of an organic thin film having nonlinear optical characteristics used in a photo-responsive section which constitutes the light-input organic EL element according to the present invention.

FIG. 19 is a characteristic diagram for explaining a method of controlling the light input type organic EL element according to the present invention.

FIG. 20 is a circuit diagram showing a control system of the light input type organic EL element according to the present invention.

FIG. 21 is a spectrum diagram showing absorption characteristics of still another example of the organic thin film used in the photoresponsive section that constitutes the light input type organic EL element according to the present invention.

FIG. 22 is a spectrum diagram showing the light transmission characteristics of still another example of the organic thin film used in the photoresponsive section which constitutes the light input type organic EL element according to the present invention.

FIG. 23 is an energy band diagram of a photo-responsive portion formed of an organic thin film doped with impurities, which constitutes the light-input organic EL element according to the present invention.

FIG. 24 is an energy band diagram of a light input type organic EL element having a photoresponsive portion formed of an organic thin film doped with impurities according to the present invention.

FIG. 25 is a perspective view of a light input type organic EL element having electrodes of a matrix structure according to the present invention.

FIG. 26 is a circuit diagram of a basic control circuit for matrix-driving the light input type organic EL element according to the present invention.

FIG. 27 is a light input type organic EL device according to Example 9 of the present invention.
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an element.

FIG. 28 is an optical input type organic E according to Example 10 of the invention.
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an L element.

FIG. 29 is a diagram showing a light input type organic E in Example 11 of the present invention.
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an L element.

FIG. 30 is an optical input type organic E according to Example 12 of the invention.
The circuit diagram of the scanning line drive circuit used for L element.

FIG. 31 is a light-input type organic E according to Example 12 of the invention.
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an L element.

FIG. 32 is an optical input type organic E in Example 13 of the present invention.
The perspective view of L element.

FIG. 33 is a light-input type organic E in Example 13 of the present invention
The top view of the display panel which consists of L elements.

FIG. 34 is a light-input type organic E in Example 13 of the present invention
FIG. 2 is a plan view showing an enlarged pixel of a display panel including an L element.

FIG. 35 is a light-input type organic E in Example 13 of the present invention
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an L element.

FIG. 36 is a light-input type organic E in Example 14 of the present invention
The light absorption spectrum of the material used for the light response part of L element.

FIG. 37 is a light-input type organic E in Example 14 of the present invention
FIG. 3 is a circuit diagram of a data line driving / photodetection circuit used for an L element.

FIG. 38 is a light-input type organic E in Example 14 of the present invention
The figure which shows the relationship between the wavelength of the input light obtained in the data line drive / photodetection circuit used for L element, and the output of a division circuit.

FIG. 39 is a light-input type organic E in Example 14 of the present invention
FIG. 6 is a circuit diagram of another data line driving / photodetection circuit used for an L element.

FIG. 40 is a light-input type organic E in Example 15 of the present invention
The light absorption spectrum of the material used for the light response part of L element.

FIG. 41 is a light-input type organic E in Example 15 of the present invention
FIG. 6 is a circuit diagram of another data line driving / photodetection circuit used for an L element.

[Explanation of symbols]

11 ... Polyester resin substrate, 12 ... Hole injection electrode,
Reference numeral 13 ... Photoresponsive portion, 14 ... Hole injection layer, 15 ... Light emitting layer, 1
6 ... Electron injection layer, 17 ... Light emitting display section, 18 ... Electron injection electrode, 19 ... Protective film, 20 ... Driving section, 21 ... Driving circuit,
22 ... Detection circuit, 31 ... Glass substrate, 32 ... Hole injecting electrode, 33 ... Hole injecting layer, 34 ... Emitting layer, 35 ... Electron injecting layer, 36 ... Emitting display section, 37 ... Photoresponsive section, 38 ... Electron injection electrode, 41 ... Polycarbonate film substrate, 4
2 ... Hole injecting electrode, 43 ... Hole injecting layer, 44 ... Emitting layer, 45 ... Electron injecting layer, 46 ... Emitting display section, 47 ... Lower layer photoresponsive section, 48 ... Electron injecting electrode, 49 ... Upper layer light Response part, 51 ... Glass substrate, 52 ... Hole injection electrode, 53 ...
Hole injection layer, 54 ... Emitting layer, 55 ... Emitting display section, 56 ...
Lower layer photoresponsive part, 57 ... Electron injection electrode, 58 ... Upper layer photoresponsive part, 61 ... Glass substrate, 62 ... Hole injection electrode, 63
... hole injection layer, 64 ... light emitting layer, 65 ... electron injection layer, 66
... Light emitting display section, 67 ... First photoresponsive section, 68 ... Second photoresponsive section, 69 ... Third photoresponsive section, 70 ... Electron injection electrode, 71 ... Polyester resin substrate, 72 ... Hole injection Electrode, 73 ... Hole injection layer also functioning as a photoresponsive section, 74 ... Hole injection layer, 75 ... Emission layer, 76 ... Electron injection layer, 77 ... Emitting display section, 78 ... Electron injection electrode, 79 ... Protective film , 101 ...
Oscillator, 102 ... Drive pulse amplifier, 103 ... Gain variable differential amplifier, 104 ... Inverter, 105 ... Detection pulse amplifier, 106 ... Drive amplifier, 107 ... Diode circuit, 108 ... Current amplifier, 109 ... Level comparator, 110 ... Display panel , 111 ... Substrate, 112 ... Scan line electrode, 113 ... Photoresponsive portion, 114 ... Hole injection layer, 11
5 ... Emitting layer, 116 ... Electron injection layer, 117 ... Emitting display section, 118 ... Data line electrode, 119 ... Pixel, 120 ... Drive control logic circuit, 130 ... Scan line drive circuit, 140 ... Image data register, 150 ... Data Line drive / photodetection circuit, 160 ... Photodetection output circuit, 170 ... Photodetection control circuit, 200 ... Data line electrode, 201 ... Switching element for driving light emission display, 202 ... Switching element for photodetection, 203 ... Detection signal Amplification circuit, 204 ... Level comparator, 205 ... Photodetection signal, 206 ... Data line address signal, 207 ... Optical input ON signal, 211 ... Switching element for driving light emission display, 212 ... Current detection / amplification circuit, 213 ... Level Comparator, 214 ... Optical input ON signal, 215 ... Data line address signal, 221 ... Switching element, 222 ... Electricity Detection and amplification circuit, 223 ... A
/ D converter, 224 ... Optical input ON signal, 225 ... Data line address signal, 231 ... Data line switching element, 232 ... Current detection / amplification circuit, 233 ... Level comparator, 234 ... Erase switching element, 235
... Data line address signal, 236 ... Erase signal, 237 ...
Optical input ON signal, 300 ... Scan line electrode, 301 ... Scan line switching element, 302 ... Erase switching element, 303 ... Erase signal, 304 ... Erase power supply, 305 ... Scan line address signal, 351 ... Glass substrate, 352 ... Hole injection electrode (scan line electrode), 353 ... Hole injection layer, 35
4 ... Light emitting layer, 355 ... Electron injection layer, 356 ... Light emitting display section, 357 ... Red light responsive section, 358 ... Blue light responsive section, 3
59, 360 ... Electron injection electrode (data line electrode), 40
0R, 400B, 400G ... Data line electrode, 401 ... Switching element for driving light emitting display, 402 ... Current detection
Amplifier circuit, 403 ... Identification circuit, 404 ... Color discrimination circuit, 4
11 ... Switching element for driving light emitting display, 412 ... Current detection / amplification circuit, 413 ... Division circuit, 414 ... A / D
Converter, 415 ... Data line address signal, 421 ...
Switching elements for driving light emitting display, 422 ... Current detecting / amplifying circuit, 423 ... Color determining circuit, 424 ... Photodetection output circuit, 425 ... Data line address signal, 426 ... Optical input signal dividing circuit, 431 ... For driving light emitting display , 432 ... Current detection / amplification circuit, 433 ... Color discrimination circuit, 434 ... Optical input signal, 434 ... Data line address signal, 436 ... Clock signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Miura 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center

Claims (7)

[Claims] 1. An organic thin film having a light emitting display portion and a photoresponsive portion, and a pair of electrodes for applying a voltage to the organic thin film, wherein light emitting display is performed according to information optically input. Characteristic light input type organic EL device. 2. The light input type organic EL device according to claim 1, wherein the light emitting display section and the light response section are composed of different organic thin films. 3. The light-input organic EL device according to claim 1, wherein the organic thin film forming the photoresponsive portion exhibits a switching response. 4. The light-input organic EL device according to claim 1, wherein the organic thin film forming the light-responsive portion is reversibly changed by light having a plurality of different wavelengths and has a memory function.
element. 5. The organic thin film forming the photo-responsive section is provided with regions showing responses to lights having different wavelengths, and has a multiple input function by a plurality of lights having these different wavelengths. Item 1. Optical input type organic E according to item 1.
L element. 6. An organic thin film forming a light emitting display section comprises at least a part of a light response section, and light emission display is performed with a forward bias, and light input with a reverse bias is detected. The light input type organic EL device according to claim 1. 7. The light input type organic EL device according to claim 1, wherein the photoresponsive portion is doped with impurities.