JP2005101009A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element or a light emitting device provided with both practical luminance and stability. <P>SOLUTION: This light emitting device has a light emitting element in which a charge injection transport medium containing an organic compound or inorganic compound and a light emitting medium are formed between a first electrode and a second electrode, the first electrode has an opening part on it, a barrier layer to cover the periphery part of the first electrode is provided, and the corner part of the opening part has a roundish shape. Also, this light emitting device has the light emitting element in which the charge injection transport medium containing the organic compound and the inorganic compound and the light emitting medium are formed between the first electrode and the second electrode, the first electrode is connected to a thin film transistor, the first electrode has the opening part on it, the barrier layer to cover the periphery part of the first electrode is provided, and the corner part of the opening part has the roundish shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light-emitting device including a charge injecting and transporting medium including an organic compound or an inorganic compound and a light-emitting element including a light-emitting medium, and more particularly, to an active matrix driving method in which an applied voltage of a light-emitting element is controlled by a field effect transistor. The present invention relates to a light emitting device.

A light-emitting element including a light emitter such as an organic electroluminescent medium is formed by stacking an organic amine-based hole transport layer between a pair of electrodes, a layer containing an organic compound such as Alq3 that exhibits electronic conductivity and also emits light, Since a luminance of several hundred cd / cm ² can be obtained by applying a DC voltage of 6 to 8 V, it has a performance applicable to a display medium or the like.

Organic compounds often used for the purpose of forming a light-emitting element are roughly classified into low molecular organic compounds and high molecular organic compounds. An example of a low molecular weight organic compound is copper phthalocyanine (CuPc) as a hole injection layer and α-NPD (4,4'-bis- [N- (naphthyl) -N-phenyl-amino) which is an aromatic amine material. ] Biphenyl), MTDATA (4,4 ', 4 "-tris (N-3-methylphenyl-N-phenyl-amino) triphenylamine) and the like, and tris-8-quinolinolato aluminum complex as the light emitting layer (Alq ₃ ), etc. Examples of the polymer organic compound material include polyaniline and polythiophene derivative (PEDOT).

  From the viewpoint of material diversity, low molecular weight organic compounds produced by vapor deposition are said to have a great variety compared to high molecular weight organic materials. In some cases, a light-emitting element is formed by combining such an organic compound material and an inorganic compound material. For example, Japanese Patent Application Laid-Open No. 2001-230082 discloses a technique for applying an inorganic electron injecting and transporting layer or an inorganic hole injecting and transporting layer to increase the lifetime with high luminous efficiency. In any case, it is known that there are various types of structures of light emitting elements.

  An example of an active matrix driving display device in which such a light emitting element is controlled by a field effect transistor is disclosed in Japanese Patent Application Laid-Open No. 8-234683. This publication discloses a configuration in which an organic electroluminescence layer is formed on an upper layer of a thin film transistor (TFT) using polycrystalline silicon via an insulating film made of silicon dioxide. Further, the passivation layer having an end processed into a tapered shape on the anode is located on the lower layer side of the organic electroluminescence layer. For the cathode, a material having a work function lower than 4 eV is selected, and an alloy of a metal such as Ag or Al and Mg is used.

  Japanese Patent Application Laid-Open No. 2001-147659 discloses an example of a current-driven display device in which a current mirror circuit is formed in each pixel by a TFT and the influence of variation in TFT characteristics can be prevented.

  However, such a conventional light-emitting element has a problem that even if sufficient luminance is obtained immediately after fabrication, the luminance is lowered due to a change with time. In other words, the luminance decreased with the increase of the accumulated light emission time, and since the time to reach the half value (half life) was short, the stability was poor and it was not very practical.

  Factors that cause deterioration of light-emitting elements include chemical changes in charge injecting and transporting media and organic light-emitting media containing organic or inorganic compounds, structural changes due to heat generation during driving, dielectric breakdown due to energization due to macro defects, electrodes Alternatively, there are factors such as deterioration of the electrode interface, structural instability based on the amorphous structure of the charge injecting and transporting medium containing the organic compound or inorganic compound and the light emitting medium, and irreversible destruction due to stress or strain due to the element structure.

  It has been found that defects such as non-light emitting points (also called dark spots) appearing in the pixel can be improved by improving the sealing method of the light emitting element. On the other hand, a decrease in emission luminance is a problem of the material itself, and it can be considered as a main factor in the structural change due to heat generation in addition to the direct cause due to current flow. Heat generation inevitably occurs as current flowing through the light emitting element as Joule heat. This not only generates heat due to current flowing through the light emitting element, but also adds heat generated by the active element of the pixel. In particular, in a current-driven light-emitting device in which a constant current is supplied by an active element of each pixel, this heat generation becomes a significant problem.

  In any case, the irreversible decrease in luminance caused by causing the light emitting element to emit light is a problem that must be solved in order to put a light emitting device using the light emitting device into practical use. For this purpose, it is necessary to improve the material of the charge injection transport medium containing the organic compound or the inorganic compound and the light emitting medium itself, but not only that but also the problem can be solved by improving the element structure, the structure of the light emitting device or the driving system. It is necessary as a countermeasure.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a light-emitting element or a light-emitting device having both practical luminance and stability.

  In order to solve the above problems, the present invention has a light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a pair of electrodes, and control for applying a voltage to the light-emitting element This is a light emitting device in which a resistor is interposed between active elements as means and voltage is applied via the resistor. When the resistor maintains a certain resistance value, the light emitting element changes over time, and the internal resistance Even if the value increases, the influence is reduced at the time of constant voltage driving. A resistor is formed on the opposite surface where a light-injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are not disposed on at least one electrode of a light-emitting element containing an organic compound serving as a light emitter between a pair of electrodes. It is.

  Further, as another configuration, a light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a pair of electrodes, and the organic compound or at least one electrode of the pair of electrodes A resistor is provided on the opposite surface on which the charge injecting and transporting medium containing the inorganic compound and the light emitting medium are not formed, and one electrode of the light emitting element applies a voltage to the light emitting element connected to a common electrode that applies a constant potential. The light emitting device is connected to an active element that is a control means, and even if the resistance keeps a certain resistance value, the light emitting element changes over time and the internal resistance value increases. The effect is reduced.

  In the structure of the present invention, the active element included in the control means for applying a voltage to the light emitting element is a field effect transistor, an insulated gate transistor, or a thin film transistor, and includes a single drain, a low concentration drain, a single gate, and a multi gate. There is no particular limitation on the structure such as a top gate type and a bottom gate (reverse stagger) type. These active elements may be formed using a semiconductor layer on an insulating surface, or may be fabricated on a single crystal or polycrystalline semiconductor substrate.

  The resistor may be formed between the active element and one electrode of the light emitting element connected thereto or between the other electrode of the light emitting element and the common potential line. The material for forming the resistor is an amorphous, microcrystalline, or polycrystalline film selected from C, Si, or Ge, an amorphous, microcrystalline, or polycrystalline film of SiC, SiGe, or these These oxides, nitrides, and oxynitrides are applied. In order to control the resistivity, P, B or the like may be doped as appropriate. Other materials that can be applied include amorphous, microcrystalline, or polycrystalline coatings selected from Ti, Mo, Ta, Al, W, In, and Zn, or oxides, nitrides, and oxynitrides thereof. Applied.

  Further, not only a resistor film but also a two-terminal nonlinear element may be interposed. A simple example is a diode, and a pin diode, a pn diode, a pi diode, an in diode, a nin diode, a pip diode, or the like formed using Si, SiGe, or SiC as appropriate can be applied.

  The charge injecting and transporting medium and the light emitting medium containing an organic compound or an inorganic compound in the light emitting element include one or a plurality of layers selected from a low molecular weight organic compound, a medium molecular weight organic compound, and a high molecular weight organic compound. You may combine with the injection | pouring transport property or a hole injection transport property inorganic compound. The phosphor can be a phenylanthracene derivative, a tetraaryldiamine derivative, a quinolinol complex derivative, a distyrylbenzene derivative, or the like, and this can be used as a host material even if a coumarin derivative, DCM, quinacridone, rubrene, or the like is added as a dopant. good. High molecular organic compounds include polyparaphenylene vinylene, polyparaphenylene, polythiophene, polyfluorene, and the like. Poly (p-phenylene vinylene): (PPV), poly (2,5-dialkoxy-1,4-phenylene vinylene) (RO-PPV), poly (2- (2′-ethyl-hexoxy) ) -5-methoxy-1,4-phenylene vinylene (poly [2- (2'-ethylhexoxy) -5-methoxy-1,4-phenylene vinylene]): (MEH-PPV), poly (2- (di (Alkoxyphenyl) -1,4-phenylene vinylene) (poly [2- (dialkoxyphenyl) -1,4-phenylene vinylene]): (ROPh-PPV), polyparaphenylene (poly [p-phenylene]): (PPP) , Poly (2,5-dialkoxy-1,4-phenylene) (poly (2,5-dialkoxy-1,4-ph enylene)): (RO-PPP), poly (2,5-dihexoxy-1,4-phenylene) (poly (2,5-dihexoxy-1,4-phenylene)), polythiophene: (PT), Poly (3-alkylthiophene): (PAT), poly (3-hexylthiophene): (PHT), poly (3-cyclohexylthiophene) (poly ( 3-cyclohexylthiophene)): (PCHT), poly (3-cyclohexyl-4-methylthiophene): (PCHMT), poly (3,4-dicyclohexylthiophene) (poly ( 3,4-dicyclohexylthiophene)): (PDCHT), poly [3- (4-octylphenyl) -thiophene]: (POPT), poly [3- (4-octyl) Phenyl) -2,2-bithiophene] (poly [3- (4-octylphenyl) -2,2-bithi ophene]): (PTOPT), polyfluorene: (PF), poly (9,9-dialkylfluorene) (poly (9,9-dialkylfluorene): (PDAF), poly (9,9-dioctylfluorene) (poly (9,9-dioctylfluorene): (PDOF)) and the like. As the inorganic compound material, diamond-like carbon (DLC), Si, Ge, and oxides or nitrides thereof may be appropriately doped with P, B, N, and the like. Alternatively, an oxide, nitride, or fluoride of an alkali metal or an alkaline earth metal, or a compound or alloy of the metal and at least Zn, Sn, V, Ru, Sm, or In may be used.

  The materials listed above are examples, and functional layers such as a hole injecting and transporting layer, a hole transporting layer, an electron injecting and transporting layer, an electron transporting layer, a light emitting layer, an electron blocking layer, and a hole blocking layer using these materials. A light-emitting element can be formed by appropriately stacking layers. Moreover, you may form the mixed layer or mixed junction which combined these each layer.

  The light-emitting device of the present invention can form a pixel including a light-emitting element, an active element, and a resistor, and can function as a display body.

  The resistance value of the resistor should take into account the current voltage and characteristics of the non-linear light-emitting element, and can be obtained from the current-voltage characteristics based on the maximum rated voltage, that is, the maximum light emission luminance for practical use. The range is 0.05 to 50 times the internal resistance value. In the present invention, the resistance value required by the resistor is ((resistance of light emitting element formed in one pixel / area of light emitting element formed in one pixel) × 0.05) Ω or more ((one pixel The resistance of the light-emitting element formed in (1) / the area of the light-emitting element formed in one pixel) × 50) Ω or less.

  Alternatively, the current voltage and characteristics of the non-linear light emitting element should be taken into consideration. When the maximum rated voltage, that is, the maximum light emission luminance for practical use is used as a reference, the current vs. voltage characteristics are taken into consideration, and The resistance value is ((electric field applied to one pixel / current density flowing through one pixel) × 0.05) Ω or more and ((electric field applied to one pixel / current density flowing through one pixel) × 50) Ω or less. It is specified.

  If the resistance value of the resistor thus defined is less than or equal to the lower limit value, the effect of inserting the resistor cannot be sufficiently obtained, and if the resistance value exceeds the upper limit value, the drive voltage increases, and the drive voltage of the active element is reduced. It becomes large and burdensome. That is, the light emitting device cannot be operated with a practical driving voltage.

Of course, the influence of heat generation cannot be further ignored by interposing a resistor in this way. However, the influence is mitigated by using an insulating material having high thermal conductivity on at least one of the lower layer side, the upper layer side, and the side wall side of the light emitting element. Aluminum oxynitride (AlO _x N _1-x : x = 0.01 to 20 atom%), aluminum nitride, silicon nitride, and DLC are selected as materials having high thermal conductivity. Further, in order to dissipate heat and suppress the temperature rise of the light emitting element, it is desirable that the light emitting element is pulsed or intermittently lit. In particular, when functioning as a display body, it is desirable to apply a time-division gradation driving method.

  When a constant voltage is applied to the light emitting element, there is a phenomenon that luminance decreases with time, which means an increase in internal resistance. Therefore, as a means of apparently mitigating the change in the internal resistance, it is realized by interposing a resistor between the active element and the light emitting element or between the light emitting element and the common potential line. Further, by forming the light-emitting element in contact with an insulating material having high thermal conductivity, heat dissipation can be improved, and deterioration can be suppressed by suppressing a temperature rise of the light-emitting element. With such a configuration of the present invention, the stability of the light emitting device can be improved.

  As described above, by providing a resistor connected in series between a light emitting element and an active element that controls the light emission, or between a light emitting element and a common potential line that applies a constant potential, light emission is achieved. It is possible to reduce a change in luminance of the element over time. That is, the structure of the present invention can improve the stability of the light emitting device. The resistor can be formed in each pixel without impairing the aperture ratio by being formed as a thin film on a wiring connecting the active element and the light emitting element or on one surface of the electrode of the light emitting element. Such an effect can be remarkably exhibited particularly at the time of constant voltage driving.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. One typical embodiment of the light-emitting device according to this embodiment is a light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a pair of electrodes, a resistor, and the light-emitting element. An image display unit is formed by arranging pixels provided with at least one active element for controlling an applied voltage in a matrix. 1A is a perspective view, FIG. 1B is a longitudinal sectional view taken along line AA ′, and FIG. 1C is a longitudinal sectional view taken along line BB ′. Yes.

  As shown in these drawings, the light emitting device includes an element substrate 10 provided with an image display region 12, a scanning line driving circuit 13, a data line driving circuit 14, an input / output terminal 15 and the like, and a color filter 18. The counter substrate 11 is fixed by a sealing material 19.

As the element substrate 10, glass, quartz, plastic, a semiconductor, a metal substrate, or the like is used. The same applies to the counter substrate 11, but at least one of the counter substrate 11 is a light-transmitting substrate so that light emission of the light-emitting element can be visually recognized. In addition, the sealing material 19 is formed along the peripheral portion of the counter substrate 11, but is superimposed on the scanning line driving circuit 13 and the data line driving circuit 14 via the interlayer insulating film 16 in the positional relationship with the element substrate. Is formed. The interlayer insulating film 16 has a flat formation surface, but the outermost surface and side surface portions are aluminum oxynitride (AlO _x N _1-x : x = 0.01 to 20 atom%), aluminum nitride, nitride It is formed of an inorganic insulator material such as silicon, DLC, silicon nitride, or silicon oxynitride.

  The image display unit 12 has a matrix formed by scanning lines and data lines extending from the scanning line driving circuit 13 and the data line driving circuit 14, and appropriately arranged switching element groups at various places, and the switching element groups electrically A pixel matrix is formed from the organic light emitting element group 17 to be connected. The scanning line driving circuit 13 is configured to be driven from both sides of the image display area 12, but when signal delay does not become a problem, only one side may be provided.

  In order to perform multicolor display, the light emitting element group 17 changes the light emission color for each pixel. For example, each color of R (red), G (green), and B (blue) is arranged in rows or columns or in a delta arrangement. The image display unit 12 is formed. Alternatively, white light emitting elements are uniformly formed on the entire surface, a color filter 18 facing the image display unit 12 is provided, and a predetermined colored layer is arranged corresponding to each pixel. The color filter 18 has an effect of increasing its color purity even when combined with a light emitting element that emits each color of R (red), G (green), and B (blue).

  An input terminal portion 15 is formed on the outer peripheral portion of the element substrate 10, and various signals are input from an external circuit and are connected to a power source. The space surrounded by the element substrate 10 and the counter substrate 11 and the sealing material 19 is filled with an inert gas to prevent the organic light emitting element group 17 from being corroded. This space may contain a desiccant such as barium oxide.

  The relationship between the light emitting element, the resistor, and the active element, which are basic components of the pixel, is shown in FIGS.

  In FIG. 11A, a light-emitting element 300 has a stacked structure in which a charge injection / transport medium containing an organic compound or an inorganic compound and a layer 302 containing a light-emitting medium are formed between a first electrode 301 and a second electrode 303. A resistor 304 having a specific resistance ρ is formed on the surface of the first electrode on which the charge injection / transport medium containing the organic compound or inorganic compound and the layer 302 containing the light emitting medium are not formed. An electrode or wiring 305 connected to the active element 305 is formed on one side of the resistor 304, and the active element 310 and the light-emitting element 300 are formed depending on the area where the first electrode 301, the resistor 304, and the electrode or wiring 305 overlap. A resistance value of the resistor 304 connected in series is defined.

  The resistor 304 is an amorphous, microcrystalline, or polycrystalline film selected from C, Si, and Ge, an amorphous, microcrystalline, or polycrystalline film of SiC, SiGe, or an oxide thereof. Nitride and oxynitride can be applied. Further, in order to control the resistivity, P, B, or the like may be doped as appropriate. Other applicable materials include amorphous, microcrystalline, or polycrystalline coatings selected from Ti, Mo, Ta, Al, W, In, and Zn, or oxides, nitrides, and oxynitrides thereof. and so on. Further, not only a resistor film but also a two-terminal nonlinear element may be interposed. A simple example is a diode, and a pin diode, a pn diode, a pi diode, an in diode, a nin diode, a pip diode, or the like formed using Si, SiGe, or SiC as appropriate can be applied.

  As described above, the resistivity of the resistor can be freely set by the film thickness and the overlapping area of the stacked body. The value to be set takes into account the current voltage and characteristics of the non-linear light emitting element, and the internal resistance obtained from the current voltage characteristics based on the maximum rated voltage, that is, the maximum light emission luminance for practical use. It shall be in the range of 0.05 to 50 times the value. Specifically, the resistance value required by the resistor is ((resistance of light emitting element formed in one pixel / area of light emitting element formed in one pixel) × 0.05) Ω or more ((one The resistance of the light emitting element formed in the pixel / the area of the light emitting element formed in one pixel) × 50) Ω or less.

  Alternatively, the current voltage and characteristics of the non-linear light emitting element should be taken into consideration. When the maximum rated voltage, that is, the maximum light emission luminance for practical use is used as a reference, the current vs. voltage characteristics are taken into consideration, and The resistance value is ((electric field applied to one pixel / current density flowing through one pixel) × 0.05) Ω or more and ((electric field applied to one pixel / current density flowing through one pixel) × 50) Ω or less. To be.

  When a constant voltage is applied to the light emitting element, there is a phenomenon that luminance decreases with time, which means an increase in internal resistance. Therefore, luminance stability can be improved by interposing a resistor between the active element and the light emitting element or between the light emitting element and the common potential line as a means of apparently mitigating the change in internal resistance. .

  FIG. 11B shows an equivalent circuit diagram thereof. The light emitting element 300 is represented by a series resistance Rs which is considered to be caused by the electric resistance of the thin film forming the diode D and the light emitting element, a capacitance C, and a parallel resistance Rsh when a leakage current flows.

  FIG. 12A shows an example in which a resistor is provided on the second electrode 303 side. The second electrode 303 is connected to a common electrode that applies a constant potential. The same effect can be obtained even if the resistor is connected to the second electrode side. FIG. 12B shows an equivalent circuit diagram thereof.

  FIG. 2 shows an example of a circuit diagram of an image display portion of a light emitting device formed with such a pixel configuration. One pixel 200 includes TFTs 201, 202, and 203, a light emitting element 205, and a resistor 204. The TFT 201 is an address selection unit that performs an on / off operation based on the signal of the scanning signal line 207, the TFT 203 is a driving unit that controls the light emission of the light emitting element 205, and the TFT 202 is on / off based on the signal of the erase signal line 208. This is a control means that operates and controls the conduction of the TFT 203 to forcibly emit light and not emit light.

  The resistor 204 inserted in series between the TFT 203 and the light emitting element 205 has a function of reducing the influence of the resistance change of the light emitting element 205, particularly during constant voltage driving, and can suppress the change in luminance.

  3 and 4 are diagrams for explaining this effect. FIG. 3 shows a conventional configuration in which a resistor is not provided, and the TFT 203 and the light emitting element 205 are directly connected. The light emitting element 205 is shown in its equivalent circuit, and is represented by a series resistance Rs that is considered to be caused by the electric resistance of the diode D and the thin film forming the light emitting element, a capacitance C, and a parallel resistance Rsh when leakage current flows. ing. Here, Rsh >> Rs is assumed and the influence of the parallel resistance is ignored.

  Here, when the voltage V is applied from the power supply line 209 via the TFT 203, the current I flowing through the light emitting element 205 is represented by V / Rs. Thereafter, when the light emitting element deteriorates and the series resistance increases to Rs + r, the current value I ′ after deterioration becomes V / (Rs + r), and the series resistance change of the light emitting element directly affects. If the increase in resistance value due to deterioration is r = Rs, the current value will eventually be ½.

  On the other hand, when a resistor 204 having a resistance value Re is inserted in series between the TFT 203 and the light emitting element 205 as shown in FIG. 4, in order to obtain the same luminance, it is necessary to increase the voltage applied from the power line 209 as V + V ′. However, the current I is (V + V ′) / (Rs + Re). Thereafter, when the light emitting element deteriorates and the series resistance increases to Rs + r, the current value I ′ after deterioration becomes (V + V ′) / (Rs + r + Re). Assuming that Rs = r = Re, the change in current value is 2/3, and when the apparent variation rate is compared, it becomes smaller when a high resistance element is interposed.

  An example of a specific structure of the pixel 200 shown in FIG. 2 is shown in FIG. FIG. 5 shows main components constituting the circuit, and shows an arrangement relationship between the TFTs 201, 202, and 203, the scanning signal line 207, the erasing signal line 208, and the power supply line 209.

  The pixel structure shown in FIG. 5 is formed on an insulating surface formed on a main surface of glass, quartz, plastic, or a semiconductor or metal material as a substrate. In the manufacturing process, as shown in FIGS. 6A and 6B, after forming semiconductor layers 103 and 104 divided into islands, a scanning signal line 207, an erasing signal line 208, and a gate electrode through a gate insulating film 106 is formed. The scanning signal line 207 and the erasing signal line 208 overlap with the semiconductor layer 103 to form gates in separate TFTs. The semiconductor layer is preferably formed using crystalline silicon, and the source and drain regions, the low concentration drain region, and the like may be formed as appropriate. Further, the stacked form of the semiconductor layer and the wiring for forming the gate may be a bottom gate type (reverse stagger type) TFT in which the wiring is first formed on the insulating surface.

  Thereafter, an interlayer insulating film is formed, and the first electrode 211 of the light emitting element is formed. When this electrode 211 is used as a hole injection electrode, a conductive material having a work function of 4 eV or more, such as an indium tin oxide alloy usually called ITO, ZnO, TiN, or TaN is applied. Alternatively, when the first electrode 211 is an electron injection electrode, the surface thereof is formed of an alloy containing an alkali metal or an alkaline earth metal, or various compounds such as oxide, fluoride, and nitride.

  Thereafter, as shown in FIG. 5, pixels are formed by forming various wirings 206, 209, 210, and 212. In addition, a partition layer 213 that covers the outer periphery of the first electrode 211 of the light emitting element is formed, and a layer containing an organic compound that serves as a light emitter is formed thereon, so that the light emitting element is formed in a self-aligning manner. A resistor is provided between the first electrode 211 of the light emitting element and the TFT 203, and the details thereof are described in a longitudinal sectional view along the line AA ′.

  In one embodiment shown in FIG. 7, a base insulating film 102, a semiconductor layer 106, a gate insulating film 105, a gate electrode 106, a first inorganic interlayer insulating film 107, an organic interlayer insulating film 108, a second inorganic interlayer insulating film are formed on a substrate 101. 109 is formed. In the source and drain regions 110 formed in the semiconductor layer 104, a power supply line 209 and a wiring 212 connected to the light emitting element are formed.

  The first inorganic interlayer insulating film 107 is formed of silicon nitride or silicon oxynitride, and prevents alkali metal or alkaline earth metal that is a constituent material of the light emitting element from diffusing into the semiconductor layer 106. The organic interlayer insulating film 108 is formed of acryl, polyimide, polyimide amide, or the like by a coating method, and the surface thereof is formed flat to improve the coverage of the light emitting element formed in the upper layer. As the second interlayer insulating film 109, silicon nitride, aluminum nitride oxide, or aluminum nitride formed by a high-frequency sputtering method is applied for the purpose of forming a dense film on the organic interlayer insulating film 108. From the viewpoint of dissipating heat generated by the TFT and the light emitting element, it is preferable to apply an insulating material having high thermal conductivity to this portion, and aluminum nitride, aluminum nitride oxide, and the like are suitable in this respect.

  A resistor 215 is interposed between the first electrode 211 and the wiring 212 of the light emitting element. The resistor is an amorphous, microcrystalline, or polycrystalline film selected from C, Si, and Ge, an amorphous, microcrystalline, or polycrystalline film of SiC, SiGe, or an oxide thereof. Nitride and oxynitride are applied. In order to control the resistivity, P, B or the like may be doped as appropriate. Other materials to be applied include amorphous, microcrystalline, or polycrystalline coatings selected from Ti, Mo, Ta, Al, W, In, and Zn or their oxides, nitrides, oxynitrides Applies.

  Of course, the actual resistance value can also be adjusted by the area of the connecting portion and the thickness of the coating, and the standard value of the intervening resistance value is the value of the internal resistance when the maximum rated voltage applied to the light emitting element is applied. It is defined by a resistivity that is in a range of 0.05 to 50 times.

  The advantage of providing a resistor will be described with reference to FIG. FIG. 16 shows the current-voltage characteristics of both terminal portions when a fixed resistor Rd is connected to the light emitting element, as shown in the inset. When Rd = 0, the current-voltage characteristic with a considerably large slope is shown. On the other hand, as Rd is increased, the slope becomes smaller. The light emitting element shows the same tendency as the internal resistance value increases with the deterioration of the brightness. However, the influence (variation rate) given by the change of the internal resistance can be reduced by connecting the fixed resistance in advance. Changes with time can be reduced.

  The resistance value of the light-emitting element varies depending on the configuration and area of a layer containing an organic compound that serves as a light emitter. The light emitting element is a light-transmitting conductive film such as indium tin oxide alloy (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), and is formed on a first electrode 211 having a thickness of 30 to 150 nm. , Preferably a layer 112 including a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light emitting medium formed with a thickness of 50 to 150 nm, and an alkali metal or alkaline earth metal such as CsF, BaF, CaF, MgAg, AlLi The second electrode 113 is formed using a conductive material including

  The partition layer 111 has an opening on the first electrode 211 and is formed so as to surround the side surface. In order to relieve the stress of the layer 112 containing the charge injection / transport medium and the light emitting medium containing the organic compound or inorganic compound formed on the upper layer of these members, the curvature of 0.2 to 3 μm is provided at the edge of the end of the opening. And the inclination angle of the side wall is preferably 35 to 70 degrees.

  The layer 112 including a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light emitting medium includes one or a plurality of layers selected from a low molecular organic compound, a medium molecular organic compound, and a high molecular organic compound, You may combine with the inorganic compound of electron injection transport property or hole injection transport property. The phosphor can be a phenylanthracene derivative, a tetraaryldiamine derivative, a quinolinol complex derivative, a distyrylbenzene derivative, or the like, and this can be used as a host material even if a coumarin derivative, DCM, quinacridone, rubrene, or the like is added as a dopant. good. High molecular organic compounds include polyparaphenylene vinylene, polyparaphenylene, polythiophene, polyfluorene, and the like. Poly (p-phenylene vinylene): (PPV), poly (2,5-dialkoxy-1,4-phenylene vinylene) (RO-PPV), poly (2- (2′-ethyl-hexoxy) ) -5-methoxy-1,4-phenylene vinylene (poly [2- (2'-ethylhexoxy) -5-methoxy-1,4-phenylene vinylene]): (MEH-PPV), poly (2- (di (Alkoxyphenyl) -1,4-phenylene vinylene) (poly [2- (dialkoxyphenyl) -1,4-phenylene vinylene]): (ROPh-PPV), polyparaphenylene (poly [p-phenylene]): (PPP) , Poly (2,5-dialkoxy-1,4-phenylene) (poly (2,5-dialkoxy-1,4-ph enylene)): (RO-PPP), poly (2,5-dihexoxy-1,4-phenylene) (poly (2,5-dihexoxy-1,4-phenylene)), polythiophene: (PT), Poly (3-alkylthiophene): (PAT), poly (3-hexylthiophene): (PHT), poly (3-cyclohexylthiophene) (poly ( 3-cyclohexylthiophene)): (PCHT), poly (3-cyclohexyl-4-methylthiophene): (PCHMT), poly (3,4-dicyclohexylthiophene) (poly ( 3,4-dicyclohexylthiophene)): (PDCHT), poly [3- (4-octylphenyl) -thiophene]: (POPT), poly [3- (4-octyl) Phenyl) -2,2-bithiophene] (poly [3- (4-octylphenyl) -2,2-bithi ophene]): (PTOPT), polyfluorene: (PF), poly (9,9-dialkylfluorene) (poly (9,9-dialkylfluorene): (PDAF), poly (9,9-dioctylfluorene) (poly (9,9-dioctylfluorene): (PDOF)) and the like. As the inorganic compound material, diamond-like carbon (DLC), Si, Ge, and oxides or nitrides thereof may be appropriately doped with P, B, N, and the like. Alternatively, an oxide, nitride, or fluoride of an alkali metal or an alkaline earth metal, or a compound or alloy of the metal and at least Zn, Sn, V, Ru, Sm, or In may be used.

In a low molecular weight organic compound, a hole injecting and transporting layer formed of copper phthalocyanine (CuPc) and aromatic amine-based material MTDATA and α-NPD, formed of a tris-8-quinolinolato aluminum complex (Alq ₃ ) It can be formed by laminating an electron injection layer and a light emitting layer. Alq ₃ enables light emission (fluorescence) from a singlet excited state. In order to increase luminance, it is preferable to use light emission (phosphorescence) from a triplet excited state. In this case, a hole injecting and transporting layer formed of CuPc, which is a phthalocyanine-based material, and α-NPD, which is an aromatic amine-based material, as the layer 21 including a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium. A structure in which a light emitting layer is formed using carbazole-based CBP + Ir (ppy) ₃ and a hole blocking layer and an electron injecting and transporting layer using Alq ₃ are stacked using bathocuproin (BCP) can also be used. .

The above two structures are examples using a low molecular weight organic compound, but an organic light emitting device combining a high molecular weight organic compound and a low molecular weight organic compound can also be realized. For example, as a layer 21 containing a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light emitting medium, from the anode side, a hole injecting and transporting layer using a polythiophene derivative (PEDOT) of a macromolecular organic compound, and hole injection using α-NPD A transport layer, a light emitting layer made of CBP + Ir (ppy) ₃ , a hole blocking layer made of BCP, and an electron injection transport layer made of Alq ₃ may be laminated. By changing the hole injection layer to PEDOT, the hole injection characteristics can be improved and the light emission efficiency can be improved.

  Moreover, you may use an inorganic compound material for a positive hole injection transport layer and an electron injection transport layer. As the inorganic compound material, diamond-like carbon (DLC), Si, Ge, and oxides or nitrides thereof may be appropriately doped with P, B, N, and the like. Alternatively, an oxide, nitride, or fluoride of an alkali metal or an alkaline earth metal, or a compound or alloy of the metal and at least Zn, Sn, V, Ru, Sm, or In may be used.

Table 1 shows an example of the internal resistance value of the light emitting element obtained when the low molecular organic compound material is used and when the high molecular organic compound material is used. In Table 1, the area of the light emitting element is 0.1 mm ² . The structure of the light-emitting element using the low molecular weight organic compound material is such that CuPc is 20 nm, α-NPD is 60 nm, Alq3: DMQd is 38 nm, Alq3 is 38 nm on the first electrode 223, and CaF is 1 nm. And Al is 200 nm. The structure of the light-emitting element using the high molecular organic compound material is a structure in which PEDOT is formed to 30 nm, PPV is formed to 80 nm, Ca is 20 nm, and Al is stacked to 100 nm as the second electrode.

  Further, as an example of a mode in which an inorganic compound material is combined with these organic compound materials, a diamond-like carbon (DLC) of 2 to 3 nm is formed on PEDOT, and a layer including a light emitter is formed thereon. Alternatively, a 2-3 nm DLC is formed on PEDOT to form a hole injection transport layer and a light emitting layer. Or it is set as the structure which laminates | stacks the laminated body of 2-3 nm DLC on PEDOT twice or more. Alternatively, a light emitting layer having the same color or different color and a DLC are stacked, and a plurality of stacked layers are stacked. Since DLC has high thermal conductivity, combining DLC as an inorganic compound material in this manner can provide an effect of suppressing a temperature increase due to heat generation of the light emitting element and reducing luminance deterioration.

The resistance value per pixel differs between a low-molecular element using a low-molecular organic compound material and a high-molecular element using a high-molecular organic compound material, and varies depending on driving conditions. resistance of 8MΩ~34MΩ are obtained when the area is caused to emit light as 4.8 × 10 ^-5 cm ² at a luminance of ^{100cd / m 2 ~200cd / m 2} . In the present invention, the resistance value required by the resistor is ((resistance of the light emitting element formed in one pixel / area of the light emitting element formed in one pixel) × 0.05) Ω or more, ((in one pixel Resistance of light emitting element to be formed / area of light emitting element formed in one pixel) × 50) Ω or less. Alternatively, the current voltage and characteristics of the non-linear light emitting element should be taken into consideration. When the maximum rated voltage, that is, the maximum light emission luminance for practical use is used as a reference, the current vs. voltage characteristics are taken into consideration, and The resistance value is ((electric field applied to one pixel / current density flowing through one pixel) × 0.05) Ω or more and ((electric field applied to one pixel / current density flowing through one pixel) × 50) Ω or less. To be.

  Based on the results in Table 1, it is sufficient to insert a resistance of 0.8 to 340 MΩ in one pixel in accordance with the resistivity of the light emitting element.

  The resistance value suitable for connection to the light emitting element originally varies depending on the driving conditions. The light emission luminance of the light emitting element is proportional to the current density flowing as shown in FIG. 13, but changes exponentially with the applied voltage as shown in FIG. That is, the current-voltage characteristics of the light-emitting element exhibit nonlinearity as shown in FIG. 15, and when the applied voltage changes, the resistance value at that time changes continuously. Accordingly, the resistance value of the resistor inserted in series should be defined with a predetermined range in a range where practical luminance can be obtained.

  If the resistance value of the resistor is sufficiently large in comparison with the resistance value of the light emitting element, it is possible to further stabilize the luminance change with time. However, the applied voltage for causing the light emitting element to emit light increases accordingly, and it is necessary to select an appropriate resistance value in consideration of the driving voltage of the light emitting device.

  By forming the resistor 215 between the TFT and the first electrode of the light emitting element, the resistor 215 can function as a protective resistor that prevents the TFT from being destroyed by static electricity. In other words, the first electrode 211 serves as an antenna when the layer 112 containing the organic compound or inorganic compound and the layer 112 containing the light emitting medium and the cathode 113 are formed by a film forming method involving charged particles such as electron beam evaporation or sputtering. The electrostatic breakdown of the TFT connected to the TFT can be prevented.

By forming the resistor in this way, the number of heat generation points when the light emitting element is driven increases. However, a member having high thermal conductivity is used for the second inorganic interlayer insulating film 109 as shown in FIG. Accordingly, heat is dissipated to the peripheral portion, and an increase in temperature of the light emitting element due to heat generation can be suppressed. In order to obtain such an effect, a film of the same material may be formed on the second electrode 113. As the member having high thermal conductivity, aluminum oxynitride (AlO _x N _1-x : x = 0.01 to 20 atom%), aluminum nitride, silicon nitride, DLC, or the like can be selected.

The arrangement of resistors different from FIG. 7 is shown in FIG. 8. After the wiring 212 connecting the power supply line 209 and the light emitting element is formed on the second inorganic interlayer insulating film 109, the resistor 215 is formed on almost the entire surface. It has become the composition. Thereafter, the first electrode 211 of the light emitting element is formed. At this time, the resistance value substantially given by the resistor 215 is defined by the area where the wiring 212, the resistor 215, and the first electrode 213 overlap. Further, the third inorganic insulating film 116 covering the upper surface portion and the side surface portion of the partition wall layer 111 is made of aluminum oxynitride (AlO _x N _1-x : x = 0.01 to 20 atom%), aluminum nitride, silicon nitride, or DLC. By forming, the heat generated in the light-emitting element is dissipated, and alteration of the charge injecting and transporting medium and the light-emitting medium containing the organic compound or inorganic compound due to the temperature rise from the portion can be prevented. Other components such as the TFT 203 are the same as those in FIG.

  Further, in the configuration shown in FIG. 9, after the wiring 212 connecting the power supply line 209 and the light emitting element is formed on the second inorganic interlayer insulating film 109, the resistor 215 is left, and the second organic interlayer insulating film 115 is further formed. The first electrode 211 of the light emitting element is formed to be electrically connected to the wiring 212. In this connection, a resistor 215 is interposed. That is, the substantial resistance value provided by the resistor 215 is defined by the area of the contact portion where the wiring 212, the resistor 215, and the first electrode 211 overlap.

  An example of forming a resistor on the second electrode side is shown in FIG. 10, the first electrode 211 and the partition wall layer 111 of the light-emitting element are formed as in FIG. 7, and then the charge injecting and transporting medium containing an organic compound or an inorganic compound and the layer 112 containing a light-emitting medium are formed. After that, the second electrode 113 is formed in a predetermined pattern, and the layer 112 including the charge injecting and transporting medium containing the organic compound or inorganic compound on the lower layer side and the light emitting medium is removed using this as an etching mask. After that, by forming the resistor 215 and the wiring 115, the resistor can be formed on the electrode side to which the common potential is applied. The substantial resistance value provided by the resistor 215 in this connection is defined by the area where the second electrode 113 and the resistor 215 overlap.

  Various electronic devices can be completed by the light-emitting device of the present invention described above. Examples thereof include portable information terminals (electronic notebooks, mobile computers, mobile phones, etc.), video cameras, digital cameras, personal computers, television receivers, mobile phones, and the like. An example of them is shown in FIG.

  FIG. 17A illustrates an example of completing a television receiver by applying the present invention, which includes a housing 3001, a support base 3002, a display portion 3003, and the like. According to the present invention, a television receiver can be completed.

  FIG. 17B shows an example in which the present invention is applied to complete a video camera, which includes a main body 3011, a display portion 3012, an audio input portion 3013, an operation switch 3014, a battery 3015, an image receiving portion 3016, and the like. . A video camera can be completed by the present invention.

  FIG. 17C illustrates an example in which a laptop personal computer is completed by applying the present invention, which includes a main body 3021, a housing 3022, a display portion 3023, a keyboard 3024, and the like. The personal computer can be completed by the present invention.

  FIG. 17D is an example in which a PDA (Personal Digital Assistant) is completed by applying the present invention, and includes a main body 3031, a stylus 3032, a display portion 3033, operation buttons 3034, an external interface 3035, and the like. A PDA can be completed by the present invention.

  FIG. 17E is an example in which a sound reproducing device is completed by applying the present invention, specifically, an in-vehicle audio device, which includes a main body 3041, a display portion 3042, operation switches 3043, 3044, and the like. Has been. According to the present invention, an audio device can be completed.

  FIG. 17F illustrates an example in which the present invention is applied to complete a digital camera. A main body 3051, a display portion (A) 3052, an eyepiece portion 3053, an operation switch 3054, a display portion (B) 3055, a battery 3056. Etc. According to the present invention, a digital camera can be completed.

  FIG. 17G illustrates an example in which a cellular phone is completed by applying the present invention, which includes a main body 3061, an audio output portion 3062, an audio input portion 3063, a display portion 3064, operation switches 3065, an antenna 3066, and the like. Yes. According to the present invention, a mobile phone can be completed.

  In addition, in addition to navigation systems, sound playback devices (car audio, audio components, etc.), personal computers, game machines, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.), refrigerator devices , Washing machines, rice cookers, landline telephones, vacuum cleaners, thermometers, etc., as well as large-area information displays, such as hanging advertisements in trains, and information on arrivals and departures at train stations and airports. be able to.

  Although the structure in which the resistor is provided in the pixel portion including the light emitting element and the active element has been described with reference to FIGS. 7 to 10, the present invention is not limited to this embodiment and can be implemented by freely combining them. can do. The preferred embodiment of the present invention has been described above. However, it will be understood by those skilled in the art that various changes can be made in the form and details without departing from the spirit and scope of the present invention. If so, it will be easily understood.

It is the perspective view and longitudinal cross-sectional view explaining the structure of the light-emitting device of this invention. It is an equivalent circuit schematic of the image display part of the light-emitting device of this invention. It is a figure explaining the variation | change_quantity of the brightness | luminance by the conventional pixel structure and a time-dependent change. It is a figure explaining the variation | change_quantity of the brightness | luminance by a pixel structure of this invention and a time-dependent change. It is a top view which shows the structure of the pixel of the pixel of this invention. It is a top view illustrating a manufacturing process of a pixel of the pixel of the present invention. It is a top view which shows the structure of the pixel of the pixel of this invention, and is a longitudinal cross-sectional view which shows the example of 1 arrangement | positioning of a resistor. It is a top view which shows the structure of the pixel of the pixel of this invention, and is a longitudinal cross-sectional view which shows the example of 1 arrangement | positioning of a resistor. It is a top view which shows the structure of the pixel of the pixel of this invention, and is a longitudinal cross-sectional view which shows the example of 1 arrangement | positioning of a resistor. It is a top view which shows the structure of the pixel of the pixel of this invention, and is a longitudinal cross-sectional view which shows the example of 1 arrangement | positioning of a resistor. It is a structure of the pixel which concerns on this invention, and is a figure explaining the connection of a light emitting element, an active element, and a resistor. It is a structure of the pixel which concerns on this invention, and is a figure explaining the connection of a light emitting element, an active element, and a resistor. It is a graph which shows the electric current vs. light-emitting luminance characteristic of a light emitting element. It is a graph which shows the voltage vs. light emission luminance characteristic of a light emitting element. It is a graph which shows the voltage vs. current characteristic of a light emitting element. It is a graph which shows a voltage versus current characteristic when resistance is connected in series with a light emitting element. It is a figure which shows the specific application example of a light-emitting device.

Claims (17)

A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a thin film transistor;
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a source or drain of a thin film transistor;
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a thin film transistor;
The second electrode is connected to a common electrode for applying a constant potential;
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a source or drain of a thin film transistor;
The second electrode is connected to a common electrode for applying a constant potential;
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to the thin film transistor through a resistor,
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to the source or drain of the thin film transistor through a resistor,
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a thin film transistor;
The second electrode is connected to a common electrode that applies a constant potential via a resistor,
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape. A light-emitting element in which a charge injecting and transporting medium containing an organic compound or an inorganic compound and a light-emitting medium are formed between a first electrode and a second electrode;
The first electrode is connected to a source or drain of a thin film transistor;
The second electrode is connected to a common electrode that applies a constant potential via a resistor,
On the first electrode, a partition layer having an opening and covering the outer periphery of the first electrode is provided,
The light emitting device according to claim 1, wherein a corner of the opening has a rounded shape.   10. The light-emitting device according to claim 2, wherein light emission is controlled by applying a voltage to the light-emitting element using the thin film transistor. 11.   11. The light emitting device according to claim 6, wherein the resistor includes one or more selected from C, Si, and Ge.   11. The resistor according to claim 6, wherein the resistor includes one or more selected from oxides or nitrides of Ti, Mo, Ta, Al, W, In, and Zn. Light-emitting device.   The resistance value of the resistor according to any one of claims 6 to 10 is in a range of 0.05 to 50 times the value of the internal resistance when a maximum rated voltage applied to the light emitting element is applied. A light emitting device characterized by the above.   11. The resistance value of the resistor according to claim 6, wherein the resistance value of the resistor is ((resistance of light emitting element formed in one pixel / area of light emitting element formed in one pixel) × 0.05) Ω. As described above, the light-emitting device is ((resistance of light-emitting element formed in one pixel / area of light-emitting element formed in one pixel) × 50) Ω or less.   11. The resistance value of the resistor according to claim 6, wherein the resistance value of the resistor is ((electric field applied to one pixel / current density flowing through one pixel) × 0.05) Ω or more ((applied to one pixel). Electric field / current density flowing through one pixel) × 50) Ω or less.   16. The light emitting device according to claim 1, wherein the light emitting element emits light by applying a constant voltage based on a digital video signal. A television, a camera, a personal computer, a portable information terminal, or an audio device comprising the light-emitting device according to claim 1.

Images