JP2005108723A - Organic electroluminescence device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence device capable of suppressing the variation of the emission luminance of a plurality of colors due to deterioration with the passage of time, and its manufacturing method. <P>SOLUTION: When the organic electroluminescent elements 50R, 50G and 50B are deteriorated with the passage of time, a drive voltage Vd impressed between a first electrode and a second electrode rises. When an operation current when the drive voltage Vd has risen to two times of an initial drive voltage Vo due to deterioration with the passage of time is made an operation current at the time of deterioration, the thickness of a hole transparent layer 16 of each organic electroluminescent element 50R, 50G and 50B is set so that the ratio of the operation current at the time of deterioration to the initial operation current is 95% or more. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescence device and a method for manufacturing the same.

  Organic electroluminescence (hereinafter referred to as organic EL) elements are expected as new self-emitting elements. The organic EL element has a laminated structure in which a carrier transport layer (electron transport layer or hole transport layer) and a light emitting layer are formed between a hole injection electrode and an electron injection electrode.

  In this organic EL element, visible light from blue to red can be obtained by selecting an organic material constituting the light emitting layer. Therefore, an organic electroluminescence device capable of full-color display (hereinafter referred to as an organic EL device) can be obtained by using a plurality of organic EL elements that emit red, green, and blue monochromatic lights that are the three primary colors (RGB) of light. ) Can be realized.

  In an active matrix organic EL device, a plurality of TFTs (thin film transistors) are provided corresponding to a plurality of organic EL elements. By turning these TFTs on and off, light emission or non-light emission of each organic EL element can be controlled.

  However, each organic EL element for realizing the three primary colors of light has different driving voltage-operating current characteristics (hereinafter referred to as voltage-current characteristics). Therefore, a complicated drive voltage circuit is required to adjust different voltage-current characteristics of each organic EL element.

  In Patent Document 1, it is possible to drive each organic thin film light emitting element with a constant driving voltage while realizing a desired luminance by changing the structure of each organic thin film light emitting element of the three primary colors of light. An organic thin film light emitting device is described.

By using the organic thin film light emitting element described in Patent Document 1, organic thin film light emitting elements having different voltage-current characteristics can be driven by an easy drive voltage circuit.
JP-A-7-94278

  However, in general, the voltage-current characteristics of an organic EL element change due to deterioration with time, and the current value flowing through the organic EL element decreases. Thereby, the brightness | luminance of an organic EL element falls.

  Since the degree of decrease in the current value depends on the organic material constituting the organic EL element, it differs for each of the red, green and blue organic EL elements. Therefore, since the ratios of the luminance reduction of the organic EL elements of the respective colors are different, the luminance balance of the organic EL elements of the three colors is changed, and color unevenness occurs on the screen during full color display.

  The objective of this invention is providing the organic electroluminescent apparatus which can suppress the dispersion | variation in the light emission luminance of several colors by deterioration with time, and its manufacturing method.

  An organic electroluminescence device according to a first invention includes a plurality of organic electroluminescence elements that emit light of a plurality of colors, and a plurality of transistors provided corresponding to the plurality of organic electroluminescence elements, respectively. Each of the electroluminescent elements includes a first electrode, an organic layer, and a second electrode in order, and each of the plurality of transistors has one electrode, the other electrode, and a control electrode, and each of the organic electroluminescent elements The first electrode is connected to one electrode of the corresponding transistor, and the power supply voltage is applied between the second electrode of each organic electroluminescence element and the other electrode of the corresponding transistor. An organic electroluminescence element and a plurality of transistors are connected, The driving voltage applied between the first electrode and the second electrode of the electroluminescent element is the initial driving voltage, the operating current flowing through each organic electroluminescent element is the initial operating current, and the driving voltage is reduced due to deterioration over time. When the operating current flowing in the organic electroluminescence element when the operating current increases to twice the initial driving voltage is set as the operating current during deterioration, the ratio of the operating current during deterioration to the initial operating current is 95% or more. The thickness of the organic layer of the electroluminescence element is set.

  In the organic electroluminescence device according to the present invention, a power supply voltage is applied between the second electrode of each organic electroluminescence element and the other electrode of the corresponding transistor. When a predetermined voltage is applied to the control electrode of each transistor, the transistor is turned on, a driving voltage is applied between the first electrode and the second electrode of the organic electroluminescence element, and an organic signal is transmitted through the transistor. An operating current flows through the electroluminescence element. Thereby, the organic electroluminescence element emits light.

  When the organic electroluminescence element deteriorates with time, the driving voltage applied between the first electrode and the second electrode increases. Here, when the initial operating current is the initial operating current and the operating current when the driving voltage rises to twice the initial driving voltage due to deterioration over time is the operating current during deterioration, the operating current during deterioration with respect to the initial operating current The thickness of the organic layer of each organic electroluminescence element is set so that the ratio of the above becomes 95% or more.

  As a result, even when the drive voltage increases due to deterioration over time, the decrease in operating current is suppressed to within 5%. Therefore, a decrease in the light emission luminance of the plurality of organic electroluminescence elements is suppressed within a certain range, and the balance of the light emission luminance of the plurality of colors can be maintained. As a result, it is possible to suppress variations in light emission luminance of multiple colors due to deterioration over time.

  The organic layer of each organic electroluminescence element includes a plurality of layers, and at least one of the plurality of layers of each organic electroluminescence element is set such that the ratio of the operating current during deterioration to the initial operating current is 95% or more. The thickness may be set.

  In this case, by setting the thickness of at least one of the plurality of layers so that the ratio of the deterioration-time operating current to the initial operating current is 95% or more, the emission luminance of the plurality of organic electroluminescence elements can be reduced. The decrease can be suppressed within a certain range. Therefore, by adjusting the thickness of the layer that does not directly affect the light emission characteristics, it is possible to maintain the balance of the light emission luminance of a plurality of colors, and to suppress the change in color balance due to deterioration over time.

  At least one layer may be a carrier transport layer.

  In this case, by setting the thickness of the carrier transport layer so that the ratio of the operating current at the time of deterioration to the initial operating current is 95% or more, the decrease in the emission luminance of the plurality of organic electroluminescence elements is within a certain range. Can be suppressed. Therefore, it is possible to maintain the balance of light emission luminances of a plurality of colors without directly affecting the light emission characteristics, and to suppress variations in light emission luminance due to deterioration with time.

  The thickness of the organic layer of each organic electroluminescence element may be set so that the ratio of the operating current during deterioration to the initial operating current is 98% or more.

  As a result, even when the drive voltage increases due to deterioration over time, the decrease in operating current is suppressed to within 2%. Therefore, a decrease in the light emission luminance of the plurality of organic electroluminescence elements is suppressed within a certain range, and the balance of the light emission luminance of the plurality of colors can be maintained more stably. As a result, it is possible to suppress variations in light emission luminance of multiple colors due to deterioration over time.

  A method for manufacturing an organic electroluminescence device according to a second aspect of the invention includes an organic including a plurality of organic electroluminescence elements that emit light of a plurality of colors, and a plurality of transistors provided corresponding to the plurality of organic electroluminescence elements, respectively. A method for manufacturing an electroluminescence device, comprising preparing a substrate provided with a plurality of transistors having a step of setting the thickness of an organic layer of a plurality of organic electroluminescence elements and one electrode, the other electrode, and a control electrode And a step of forming a plurality of organic electroluminescent elements having a first electrode, an organic layer, and a second electrode on a substrate, wherein the first electrode of each organic electroluminescent element corresponds to a corresponding transistor. Connected to one electrode and each organic electroluminescent The plurality of organic electroluminescence elements and the plurality of transistors are connected so that a power supply voltage is applied between the second electrode of the transistor element and the other electrode of the corresponding transistor. A driving voltage applied between the first electrode and the second electrode is an initial driving voltage, an operating current flowing through each organic electroluminescence element is an initial operating current, and the driving voltage is 2 of the initial driving voltage due to deterioration over time. When the operating current flowing through the organic electroluminescence element when the operating current is doubled is defined as the operating current during deterioration, the ratio of the operating current during deterioration to the initial operating current is 95% or more. The layer thickness is set.

  According to the manufacturing method of the organic electroluminescent device according to the present invention, the thickness of the organic layer of the plurality of organic electroluminescent elements is set. A substrate provided with a plurality of transistors each having one electrode, the other electrode, and a control electrode is prepared. Furthermore, a plurality of organic electroluminescence elements having a first electrode, an organic layer, and a second electrode are formed on the substrate.

  In this case, the first electrode of each organic electroluminescence element is connected to one electrode of the corresponding transistor, and the power supply voltage is connected between the second electrode of each organic electroluminescence element and the other electrode of the corresponding transistor. The plurality of organic electroluminescence elements and the plurality of transistors are connected so that is applied.

  In addition, when the initial operating current is the initial operating current, and the operating current when the driving voltage rises to twice the initial driving voltage due to deterioration over time is the operating current during deterioration, the operating current during deterioration relative to the initial operating current is The thickness of the organic layer of each organic electroluminescence element is set so that the ratio is 95% or more.

  As a result, even when the drive voltage increases due to deterioration over time, the decrease in operating current is suppressed to within 5%. Therefore, a decrease in the light emission luminance of the plurality of organic electroluminescence elements is suppressed within a certain range, and the balance of the light emission luminance of the plurality of colors can be maintained. As a result, it is possible to suppress variations in light emission luminance of multiple colors due to deterioration over time.

  The thickness of the organic layer of each organic electroluminescence element may be set so that the ratio of the operating current during deterioration to the initial operating current is 98% or more.

  As a result, even when the drive voltage increases due to deterioration over time, the decrease in operating current is suppressed to within 2%. Therefore, a decrease in the light emission luminance of the plurality of organic electroluminescence elements is suppressed within a certain range, and the balance of the light emission luminance of the plurality of colors can be maintained more stably. As a result, it is possible to suppress variations in light emission luminance of multiple colors due to deterioration over time.

  According to the present invention, by setting the thickness of the organic layer of each organic electroluminescent element so that the ratio of the operating current during deterioration to the initial operating current is 95% or more, the emission luminance of multiple colors due to deterioration over time Can be suppressed.

  Hereinafter, an organic electroluminescence (hereinafter abbreviated as organic EL) device according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic plan view showing an organic EL device according to an embodiment, and FIG. 2 is a cross-sectional view of the organic EL device of FIG.

  In the organic EL device 100 of FIGS. 1 and 2, the organic EL element 50R that emits red light, the organic EL element 50G that emits green light, and the organic EL element 50B that emits blue light are arranged in a matrix.

  In FIG. 1, an organic EL element 50R, an organic EL element 50G, and an organic EL element 50B are provided in order.

  Each organic EL element 50R, 50G, 50B is formed in a region surrounded by two gate signal lines 51 extending in the row direction and two drain signal lines (data lines) 52 extending in the column direction. In each region, an n-channel TFT (thin film transistor) 130 as a switching element is formed near the intersection of the gate signal line 51 and the drain signal line 52, and each organic EL element 50R, 50G, 50B is formed near the center. A p-channel TFT 140 for driving is formed.

  Further, an auxiliary electrode 70 and a hole injection electrode 12 made of ITO are formed in each region. Organic EL elements 50R, 50G, and 50B are formed in an island shape in the region of the hole injection electrode 12 (see FIG. 2).

  The drain of the TFT 130 is connected to the drain signal line 52 through the drain electrode 13d, and the source of the TFT 130 is connected to the electrode 55 through the source electrode 13s. The gate electrode 111 of the TFT 130 extends from the gate signal line 51.

  The auxiliary capacitor 70 includes an SC line 54 that receives the power supply voltage Vsc, and an electrode 55 that is integrated with the active layer 11 (see FIG. 2).

  The drain of the TFT 140 is connected to the hole injection electrode 12 of the organic EL elements 50R, 50G, and 50B through the drain electrode 43d, and the source of the TFT 140 is connected to the power supply line 53 extending in the column direction through the source electrode 43s. . The gate electrode 41 of the TFT 140 is connected to the electrode 55.

  Next, as shown in FIG. 2, an active layer 11 made of polycrystalline silicon or the like is formed on the glass substrate 10, and a part of the active layer 11 drives the organic EL elements 50R, 50G, and 50B. TFT 140 is formed. A gate electrode 41 having a double gate structure is formed on the active layer 11 via a gate oxide film (not shown), and the interlayer insulating film 13 and the first planarization layer are formed on the active layer 11 so as to cover the gate electrode 41. 15 is formed.

  As a material of the first planarization layer 15, for example, an acrylic resin can be used. A transparent hole injection electrode 12 is formed for each pixel on the first planarization layer 15, and an insulating second planarization layer 18 is formed on the first planarization layer 15 so as to cover the hole injection electrode 12. Is formed.

  The TFT 140 is formed under the second planarization layer 18. Here, the second planarization layer 18 is not formed on the entire surface of the hole injection electrode 12, but covers the region in which the TFT 140 is formed and has the shape of the second planarization layer 18. Or it forms locally so that each below-mentioned organic material layer may not be disconnected.

  A hole transport layer 16 is formed so as to cover the hole injection electrode 12 and the second planarization layer 18.

  A red light emitting layer 22, a green light emitting layer 24, and a blue light emitting layer 26 are formed on the hole transport layer 16 of the organic EL element 50R, the organic EL element 50G, and the organic EL element 50B, respectively.

  A boundary between the red light emitting layer 22, the green light emitting layer 24 and the blue light emitting layer 26 is provided in a region parallel to the glass substrate 10 on the surface of the second planarizing layer 18.

  On the organic EL element 50R, the organic EL element 50G, and the organic EL element 50B, the electron transport layer 28 is formed on the red light emitting layer 22, the green light emitting layer 24, and the blue light emitting layer 26, respectively.

  Further, an electron injection layer 30 is formed on each electron transport layer 28, and a common electron injection electrode 32 is formed on the electron injection layer 30. A protective layer 34 made of resin or the like is formed on the electron injection electrode 32, and a filter F is provided on the protective layer 34.

  The hole transport layer 16, the light emitting layer 22, the electron transport layer 28, and the electron injection layer 30 of the organic EL element 50R constitute an organic layer, and the hole transport layer 16, the light emitting layer 24, the electron transport layer 28, and the electrons of the organic EL element 50G. The injection layer 30 constitutes an organic layer, and the hole transport layer 16, the light emitting layer 26, the electron transport layer 28, and the electron injection layer 30 of the organic EL element 50B constitute an organic layer.

  FIG. 3 is a circuit diagram showing the connection between the organic EL element 50G and the TFT 140. As shown in FIG.

  As shown in FIG. 3, the gate of the TFT 140 is connected to the positive electrode of the DC power supply 60 via the gate signal line 51, the drain is connected to the hole injection electrode 12 of the organic EL element 50G via the drain signal line 52, and the source Is connected to the positive electrode of a DC power supply 61 through a power line 53. The electron injection electrode 32 of the organic EL element 50G is connected to the negative electrodes of the DC electrodes 60 and 61. The power supply voltage of the DC power supply 61 is Vt (V).

  Vf represents a driving voltage applied to the organic EL element 50G, Vds represents a voltage applied between the drain and source of the TFT 140 (drain-source voltage), and Vgs represents a gate voltage of the TFT 140. Here, the power supply voltage Vt is the sum of the drive voltage Vf and the drain-source voltage Vds. I represents an operating current flowing through the organic EL element 50G.

  The connection between the organic EL element 50R and the TFT 140 and the connection between the organic EL element 50B and the TFT 140 are the same as the connection between the organic EL element 50G and the TFT 140.

  FIG. 4 is a diagram showing the driving voltage-operating current characteristics of the organic EL elements 50R, 50G, 50B and the drain-source voltage-drain-source current characteristics of the TFT 140. The vertical axis in FIG. 4 indicates the current value, and the horizontal axis indicates the voltage value.

  Hereinafter, the drive voltage-operating current characteristics of the organic EL elements 50R, 50G, 50B are referred to as Vf-I characteristics, and the drain-source voltage-drain-source current characteristics of the TFT 140 are referred to as Vds-I characteristics.

  Here, the curve CR indicates the Vf-I characteristic of the organic EL element 50R, the curve CG indicates the Vf-I characteristic of the organic EL element 50G, and the curve CB indicates the Vf-I characteristic of the organic EL element 50B. Curves DS1, DS2, DS3, DS4, and DS5 indicate Vds-I characteristics of the TFT 140 when the gate voltage Vgs is changed.

  For example, in this embodiment, it is assumed that the gate voltage Vgs is set so that the Vds-I characteristic of the TFT 140 is indicated by a curve DS3.

  In this case, the voltage at the intersection of the curve DS3 and each of the curves CR, CG, CB becomes the drive voltage Vf of the organic EL elements 50R, 50G, 50B, and the current at the intersection of the curve DS3 and each of the curves CR, CG, CB is organic. This is the operating current I of the EL elements 50R, 50G, 50B.

  For example, the drive voltage Vf of the organic EL element 50G is VG, and the operating current I is IG.

  Here, the Vf-I characteristics of the organic EL elements 50R, 50G, and 50B shift to the right, that is, the direction in which the drive voltage Vf increases due to deterioration with time. Thereby, the operating current I decreases. Hereinafter, a change in the Vf-I characteristic due to deterioration with time of the organic EL element 50G will be described in detail.

  FIG. 5 is a diagram showing a change in the Vf-I characteristic when the organic EL element 50G deteriorates with time. The vertical axis in FIG. 5 indicates the current value, and the horizontal axis indicates the voltage value.

  Here, it is defined that the organic EL element 50G has deteriorated when the drive voltage Vf of the organic EL element 50G increases to twice the initial drive voltage. That is, when the initial driving voltage Vf of the organic EL element 50G is Vf0, 2Vf0 is defined as the deterioration driving voltage.

  In the organic EL element 50G, the Vf-I characteristic varies depending on the thickness of the organic layer.

  For example, the curve G1 shows the Vf-I characteristic when the thickness of the organic layer is t1. At this time, the initial drive voltage Vf0 is VG1, and the initial operating current I is IG1. When the organic EL element 50G deteriorates with time, the Vf-I characteristic shifts to the curve G1a. At this time, the deterioration driving voltage 2Vf0 is VG1a. The operating current at the time of deterioration is IG1a.

  From the above, the organic EL element 50G having the organic layer thickness t1 has the operating current reduced from IG1 to IG1a due to deterioration over time. In the example of FIG. 5, the ratio of the deterioration-time operating current IG1a to the initial operating current IG1 is about 80%. Thereby, the luminance is reduced by about 20%.

  On the other hand, the Vf-I characteristic when the thickness of the organic layer is t2 is indicated by a curve G2. At this time, the initial drive voltage Vf0 is VG2, and the initial operating current is IG2. When the organic EL element 50G deteriorates with time, the Vf-I characteristic shifts to the curve G2a. At this time, the deterioration driving voltage 2Vf0 is VG2a. The operating current at the time of deterioration is IG2a. In the example of FIG. 5, the ratio of the degradation operating current IG2a to the initial operating current IG2 is about 100%. Thereby, the luminance does not decrease.

  From the above, when the film thickness t2 of the organic layer of the organic EL element 50G is set, the operating current hardly decreases due to deterioration over time, so that the emission luminance of the organic EL element 50G can be prevented from decreasing.

  Therefore, in this embodiment, when the initial operating current is I0 and the degradation operating current is I1, the thickness of the organic layer is such that the ratio of the degradation operating current I1 to the initial operating current I0 is 95% or more. Set. That is, the film thickness of the organic layer is set so that the deterioration driving voltage is located in the saturation region of the Vds-I characteristic. Or you may set the thickness of an organic layer so that the ratio of the brightness | luminance at the time of deterioration with respect to the initial stage brightness | luminance of the organic EL element 50G may be 90% or more.

  Similarly, in the organic EL element 50R and the organic EL element 50B, similarly to the organic EL element 50G, the thickness of the organic layer is set so that the ratio of the operating current I1 during deterioration to the initial operating current I0 is 95% or more. To do. Alternatively, in the organic EL element 50R and the organic EL element 50B, the thickness of the organic layer may be set so that the ratio of the luminance at the time of deterioration to the initial luminance is 90% or more.

  Furthermore, it is preferable to set the thickness of the organic layer so that the ratio of the degradation operating current I1 to the initial operating current I0 is 98% or more.

  When setting the thickness of the organic layers of the organic EL elements 50R, 50G, and 50B, the thickness of the hole transport layer 16 may be adjusted, and the thickness of the light emitting layers 22, 24, and 26 may be adjusted. The thickness of the electron transport layer 28 may be adjusted, and the thickness of the electron injection layer 30 may be adjusted.

  As described above, the thickness of the organic layer is set so that the ratio of the deterioration-time operating current I1 to the initial operating current I0 is 95% or more even when the driving voltage is increased due to deterioration with time of the organic EL elements 50R, 50G, 50B. By setting, the decrease in the operating current of each organic EL element 50R, 50G, 50B can be suppressed within 5%. Therefore, a decrease in the light emission luminance of the plurality of organic EL elements 50R, 50G, 50B is suppressed within 10%, and the balance of the light emission luminance of the plurality of colors can be maintained. As a result, it is possible to suppress variations in light emission luminance of multiple colors due to deterioration over time.

  In the present embodiment, the organic electroluminescence elements 50R, 50G, and 50B correspond to a plurality of organic electroluminescence elements, the TFTs 130 and 140 correspond to a plurality of transistors, and the hole injection electrode 12 corresponds to a first electrode. The hole transport layer 16, the light emitting layers 22, 24, 26, the electron transport layer 28, and the electron injection layer 30 correspond to an organic layer, the electron injection electrode 32 corresponds to a second electrode, and the source electrode and the drain electrode are one of them. The gate electrode corresponds to the control electrode, and the hole transport layer 16 corresponds to the carrier transport layer.

  Hereinafter, the organic EL element of Examples 1-4 was produced about the said one embodiment, and it investigated about the drive voltage increase rate and luminance fall of the organic EL element.

[Example 1]
FIG. 6 is a schematic cross-sectional view showing organic EL elements 50R, 50G, and 50B produced in Examples 1 to 4.

  Note that the substrate including the glass substrate 10, the active layer 11, the interlayer insulating film 13, the first planarization layer 15, the TFT 130, and the TFT 140 described in the above embodiment is referred to as a substrate 1. In Examples 1 to 4, the electron injection layer 30 in FIG. 2 is not provided.

  As shown in FIG. 6, the organic EL elements 50R, 50G, 50B in Example 1 are the substrate 1, the hole injection electrode 12, the hole transport layer 16, the light emitting layers 22, 24, 26, the electron transport layer 28, and the electron injection electrode. 32 were laminated in order.

  In the organic EL element 50R, ITO is used as the hole injection electrode 12, and N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine represented by the following formula (1) is used as the hole transport layer 16. (N, N′-Di (naphthalene-1-yl) -N, N′-diphenyl-benzidine: hereinafter abbreviated as NPB) was used. Tris (8-hydroxyquinolinato) aluminum (hereinafter abbreviated as Alq) represented by the following formula (2) is used as a host material for the red light emitting layer 22 and the following formula (3) is used. 1.4% of (2- (1,1-dimethylethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-lII, 5II- Benzo [ij] quinolizin-9-yl) ethenyl) -4H-pyran-4-ylidene) propanedinitrile (2- (1,1-Dimethylethyl) -6- (2- (2,3,6,7-tetrahydro) -1,1,7,7-tetramethyl-lII, 5II-benzo [ij] quinolizin-9-yl) ethenyl) -4H-pyran-4-ylidene) propanedinitrile: hereinafter abbreviated as DCJTB. ) As a red dopant, Alq was used as the electron transport layer 28, and Al was used as the electron injection electrode 32.

  Further, in the organic EL element 50G, ITO was used as the hole injection electrode 12, and NPB was used as the hole transport layer 16. Alq is used as a host material for the green light emitting layer 24, and 1.0% of 10- (2-benzothiazolyl) -2,3,6,7-tetrahydro-1,1,7,7 shown in the following formula (4). -tetramethyl-1H, 5H, 11H- [1] Benzopyrano [6,7,8-ij] quinolizin-11-one (hereinafter abbreviated as C545T) was used as a green light-emitting dopant. Alq was used as the electron transport layer 28 and Al was used as the electron injection electrode 32.

  Furthermore, in the organic EL element 50B, ITO was used as the hole injection electrode 12, and NPB was used as the hole transport layer 16. As a host material for the blue light-emitting layer 26, tert-butyl-substituted dinaphthylanthracene represented by the following formula (5) was used, and 1.0% berylene was used as a blue light-emitting dopant. Alq was used as the electron transport layer 28 and Al was used as the electron injection electrode 32.

  Here, in Example 1, the thickness of the hole transport layer 16 made of NPB of the organic EL element 50R, the organic EL element 50G, and the organic EL element 50B was 1900 mm.

[Example 2]
The cross-sectional structure of the organic EL device in Example 2 is the same as the cross-sectional structure of the organic EL device shown in FIG.

  The organic EL device in Example 2 is the same as Example 1 except that the thickness of the hole transport layer 16 is 1500 mm.

[Example 3]
The cross-sectional structure of the organic EL device in Example 3 is the same as the cross-sectional structure of the organic EL device shown in FIG.

  The organic EL device in Example 3 is the same as Example 1 except that the thickness of the hole transport layer 16 is 1200 mm.

[Example 4]
The cross-sectional structure of the organic EL device in Example 4 is the same as the cross-sectional structure of the organic EL device shown in FIG.

  The organic EL device in Example 4 is the same as Example 1 except that the thickness of the hole transport layer 16 is 500 mm.

[Evaluation]
Table 1 shows the results of examining the luminance ratio and the operating current ratio by leaving the organic EL elements produced in Examples 1 to 4 in an atmosphere of 85 ° C. for 146 hours. The initial current density at the hole injection electrode 12 and the electron injection electrode 32 is 20 mA / cm ² . Further, the ratio of the driving voltage when the organic EL element is deteriorated to the initial driving voltage is about twice.

  Here, the luminance ratio is the ratio of the luminance at the time of deterioration to the initial luminance of the organic EL element. The operating current ratio is the ratio of the operating current at the time of deterioration to the initial operating current of the organic EL element.

  In the organic EL elements 50B of Examples 1 to 4, when the film thickness of the hole transport layer 16 was 500 mm and 1200 mm, the luminance ratio was 90% or more, that is, the luminance reduction rate was within 10%. Further, the operating current ratio was 95% or more, that is, the operating current reduction rate was within 5%. When the thickness of the hole transport layer 16 was 500 mm, the operating current ratio was 98% or more, that is, the operating current reduction rate was within 2%.

  On the other hand, when the film thickness of the hole transport layer 16 was 1500 mm and 1900 mm, the luminance ratio was lower than 90%, that is, the luminance reduction rate was higher than 10%. Further, the operating current ratio was lower than 95%, that is, the operating current reduction rate was higher than 5%.

  Therefore, it was found that in the organic EL element 50B, the thickness of the hole transport layer 16 is preferably set to 500 to 1200 mm, and the thickness of the hole transport layer 16 is further preferably set to 500 mm.

  Next, in the organic EL elements 50R of Examples 1 to 4, when the film thickness of the hole transport layer 16 was 500 mm and 1200 mm, the luminance ratio was 90% or more, that is, the luminance reduction rate was within 10%. Further, the operating current ratio was 95% or more, that is, the operating current reduction rate was within 5%. When the thickness of the hole transport layer 16 was 500 mm, the operating current ratio was 98% or more, that is, the operating current reduction rate was within 2%.

  On the other hand, when the film thickness of the hole transport layer 16 was 1500 mm and 1900 mm, the luminance ratio was lower than 90%, that is, the luminance reduction rate was higher than 10%. Further, the operating current ratio was lower than 95%, that is, the operating current reduction rate was higher than 5%.

  Therefore, it was found that in the organic EL element 50R, the thickness of the hole transport layer 16 is preferably set to 500 mm to 1200 mm, and the film thickness of the hole transport layer 16 is more preferably set to 500 mm.

  Subsequently, in the organic EL elements 50G of Examples 1 to 4, when the film thickness of the hole transport layer 16 is 500 mm, 1200 mm, and 1500 mm, the luminance ratio is 90% or more, that is, the luminance reduction rate is within 10%. It was. Further, the operating current ratio was 95% or more, that is, the operating current reduction rate was within 5%. Further, when the thickness of the hole transport layer 16 was 500 mm and 1200 mm, the operating current ratio was 98% or more, that is, the operating current reduction rate was within 2%.

  On the other hand, when the film thickness of the hole transport layer 16 was 1900 mm, the luminance ratio was lower than 90%, that is, the luminance reduction rate was higher than 10%. Further, the operating current ratio was lower than 95%, that is, the operating current reduction rate was higher than 5%.

  Therefore, it was found that in the organic EL element 50R, the thickness of the hole transport layer 16 is preferably set to 500 mm to 1500 mm, and the thickness of the hole transport layer 16 is further preferably set to 500 mm to 1200 mm.

  From the above, the film thickness of the hole transport layer 16 of the organic EL element 50G of the organic EL device is 1500 mm, the film thickness of the hole transport layer 16 of the organic EL element 50B is 1200 mm, and the film of the hole transport layer 16 of the organic EL element 50R. By setting the thickness to 1200 mm, it is possible to suppress a decrease in operating current and a decrease in luminance due to deterioration of the organic EL elements 50R, 50G, and 50B.

  INDUSTRIAL APPLICABILITY The present invention can be used for an organic electroluminescence device capable of suppressing variations in light emission luminance of multiple colors due to deterioration with time and a method for manufacturing the same.

1 is a schematic plan view showing an organic EL device according to an embodiment. FIG. 2 is a cross-sectional view of the organic EL device of FIG. 1 taken along line AA. It is a circuit diagram which shows the connection of an organic EL element and TFT. It is a figure which shows the drive voltage-operating current characteristic of an organic EL element, and the drain-source voltage-drain-source current characteristic of TFT. It is a figure which shows the change of the Vf-I characteristic at the time of time-dependent deterioration of an organic EL element. It is typical structure sectional drawing which shows the organic EL element produced in Examples 1-4.

Explanation of symbols

12 hole injection electrode 16 hole transport layer 22, 24, 26 light emitting layer 28 electron transport layer 30 electron injection layer 32 electron injection electrode 50R, 50G, 50B organic electroluminescence device 130, 140 TFT

Claims (6)

A plurality of organic electroluminescent elements that emit light of a plurality of colors;
A plurality of transistors provided corresponding to each of the plurality of organic electroluminescence elements,
Each of the plurality of organic electroluminescence elements includes a first electrode, an organic layer, and a second electrode in order,
Each of the plurality of transistors has one electrode, the other electrode, and a control electrode,
The first electrode of each organic electroluminescence element is connected to the one electrode of the corresponding transistor, and a power source is connected between the second electrode of each organic electroluminescence element and the other electrode of the corresponding transistor. The plurality of organic electroluminescence elements and the plurality of transistors are connected so that a voltage is applied,
Initially, a driving voltage applied between the first electrode and the second electrode of each organic electroluminescence element is an initial driving voltage, an operating current flowing through each organic electroluminescence element is an initial operating current, When the operating current flowing through the organic electroluminescence element when the driving voltage has increased to twice the initial driving voltage due to deterioration is set as the operating current during deterioration,
An organic electroluminescent device, wherein the thickness of the organic layer of each organic electroluminescent element is set so that the ratio of the operating current during deterioration to the initial operating current is 95% or more. The organic layer of each organic electroluminescence element includes a plurality of layers,
The thickness of at least one of the plurality of layers of each organic electroluminescence element is set so that a ratio of the operating current during deterioration to the initial operating current is 95% or more. Item 2. The organic electroluminescence device according to Item 1. The organic electroluminescence device according to claim 2, wherein the at least one layer is a carrier transport layer. The thickness of the said organic layer of each organic electroluminescent element was set so that the ratio of the said operating current at the time of deterioration with respect to the said initial stage operating current might be 98% or more. The organic electroluminescent device according to 1. A method of manufacturing an organic electroluminescence device comprising a plurality of organic electroluminescence elements that emit light of a plurality of colors and a plurality of transistors provided corresponding to the plurality of organic electroluminescence elements, respectively.
Setting the thickness of the organic layer of the plurality of organic electroluminescence elements;
Preparing a substrate provided with the plurality of transistors having one electrode, the other electrode and a control electrode;
Forming the plurality of organic electroluminescent elements having a first electrode, an organic layer, and a second electrode on the substrate,
The first electrode of each organic electroluminescence element is connected to the one electrode of the corresponding transistor, and a power source is connected between the second electrode of each organic electroluminescence element and the other electrode of the corresponding transistor. Connecting the plurality of organic electroluminescence elements and the plurality of transistors such that a voltage is applied;
Initially, a driving voltage applied between the first electrode and the second electrode of each organic electroluminescence element is an initial driving voltage, an operating current flowing through each organic electroluminescence element is an initial operating current, When the operating current flowing through the organic electroluminescence element when the driving voltage is increased to twice the initial driving voltage due to deterioration is set as the operating current during deterioration,
A method of manufacturing an organic electroluminescent device, wherein the thickness of the organic layer of each organic electroluminescent element is set so that the ratio of the operating current during deterioration to the initial operating current is 95% or more. 6. The organic electroluminescence device according to claim 5, wherein the thickness of the organic layer of each organic electroluminescence element is set so that a ratio of the deterioration-time operating current to the initial operating current is 98% or more. Manufacturing method.

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