JP2012018939A - Light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of suppressing brightness variations of a light-emitting element having a resonator structure even if, for example, a film thickness is deviated from a design value and a resonator's optical path length increases or decreases.SOLUTION: A light-emitting element comprises: a first reflection member, a second reflection member; a light-emitting layer disposed between the first reflection member and the second reflection member; and a resonator structure in which part of the light resonated between the first reflection member and the second reflection member is transmitted by the first reflection member and the second reflection member. The maximum wavelength of a resonator output spectrum from the resonator structure is in the range between 90% and 50% of the maximum light emission intensity of an internal emission spectrum of the light-emitting layer, and the maximum wavelength of the internal emission spectrum is in the range from 450 nm to 480 nm.

Description

  The present invention relates to a light emitting element.

  As a light-emitting element that constitutes a display device such as a display device or a lighting device, an EL element using a substance that emits light by an electroluminescence (EL) phenomenon when a voltage is applied is known. The EL element is a thin-film light-emitting element in which a light-emitting layer made of an organic material or an inorganic material is formed between an upper electrode and a lower electrode, and has a structure in which a voltage is applied to the light-emitting layer at the upper and lower electrodes to emit light. .

  In recent years, one of the upper electrode and the lower electrode is a total reflection mirror, and the other is a transflective mirror that transmits a part of the wavelength, thereby resonating the light emitted from the light emitting layer (so-called microscopic structure). A light emitting device having a cavity structure has been developed (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses a light emitting device that reduces the viewing angle dependency of white by shifting the peak wavelength of the internal emission spectrum and the peak wavelength of the multiple interference spectrum by the resonance part from each other. The peak wavelength of the red (R) multiple interference spectrum is shifted to the long wavelength side (+10 nm), the peak wavelength of the green (G) multiple interference spectrum is shifted to the long wavelength side (+4 nm), and the blue (B) multiple interference spectrum By shifting the peak wavelength to the short wavelength side (−10 nm), the white viewing angle dependency is reduced.

  Patent Document 2 also discloses a light-emitting element that reduces the viewing angle dependency by shifting the peak wavelength of the internal emission spectrum and the peak wavelength of the multiple interference spectrum by the resonator. However, unlike Patent Document 1, the peak wavelengths of the red (R) and blue (B) multiple interference spectra are made to coincide with the peak wavelength of the internal emission spectrum.

  The techniques disclosed in Patent Documents 1 and 2 may be effective for a display device that requires a wide viewing angle characteristic such as a large display, but for example, a portable terminal, a personal computer, In the case of a small display used exclusively for personal use, such as a car navigation system, the luminance variation in the front direction may be unacceptable.

  That is, in the case of the resonator structure, the luminance in the front direction increases due to the filter characteristics and the strong directivity of the light emission output. Display devices that are used personally, for example, that do not require a wide viewing angle characteristic, use this directivity, and therefore, the luminance in the front direction varies as compared to televisions that require a wide viewing angle. Less is required. However, a thin film light-emitting device with a resonator structure has a filter characteristic that is sensitive to the distance between the mirrors (resonator optical path length), and when the optical path length varies due to manufacturing errors in the manufacturing process, the color coordinates in the front direction (Color purity) and luminance fluctuation may not be acceptable.

JP 2002-367770 A JP 2007-316611 A

  That is, the above-described problem is given as an example of the problem to be solved by the present invention. Therefore, an object of the present invention is to provide a technique capable of suppressing luminance fluctuations even when the resonator optical path length is increased or decreased, for example, when the film thickness is out of the design value in a light emitting element and display device having a resonator structure. Is given as an example.

  The light emitting device of the present invention has a first reflecting member, a second reflecting member, and a light emitting layer disposed between the first reflecting member and the second reflecting member, as described in claim 1. A resonator structure that transmits a part of light resonated between the first reflecting member and the second reflecting member through the first reflecting member or the second reflecting member; and resonance from the resonator structure. The wavelength that becomes the maximum value of the output spectrum of the light source is located in the range of 90% to 50% of the emission intensity that becomes the maximum value of the internal emission spectrum of the light emitting layer, and the wavelength that becomes the maximum value of the internal emission spectrum is 450 nm. It is in the range of ˜480 nm.

  As described in claim 6, the display device of the present invention has a first reflecting member, a second reflecting member, and a light emitting layer disposed between the first reflecting member and the second reflecting member, A resonator structure that transmits a part of light resonated between the first reflecting member and the second reflecting member through the first reflecting member or the second reflecting member, and the resonator from the resonator structure; The wavelength that is the maximum value of the output spectrum is located in the range of 95% to 50% of the emission intensity that is the maximum value of the internal emission spectrum of the light emitting layer, and the wavelength that is the maximum value of the internal emission spectrum is 600 nm to It is characterized by being in the range of 640 nm.

1 is a longitudinal sectional view of a light emitting device according to a preferred first embodiment of the present invention. 1 is a plan view of a light emitting device according to a preferred first embodiment of the present invention. It is a figure which shows the optical spectrum when blue (B) is made into object. It is a figure which shows the relationship between luminous intensity change rate _RE and luminance change rate when blue (B) is made into object. It is a figure which shows the relationship between the film thickness change when it makes blue (B) object, and a front luminance value. It is a figure which shows the optical spectrum when blue (B) is made into object. It is a figure which shows the optical spectrum when red (R) is made into object. It is a figure which shows the optical spectrum when red (R) is made into object. It is a figure which shows the relationship between the film thickness change when it makes red (R) object, and front luminance value. FIG. 6 is a longitudinal sectional view of a light emitting device according to a fourth embodiment of the present invention. FIG. 6 is a longitudinal sectional view of a light emitting device according to a preferred fifth embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Organic layer 31 Hole injection layer 32 Hole transport layer 33 Light emitting layer 34 Electron transport layer 4 Cathode 5 Partition

  Hereinafter, a light emitting device and a display device according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a display device including light emitting elements that respectively emit red (R), green (G), and blue (B) will be described as an example. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

(First embodiment)
1 and 2, an RGB unit is formed by arranging three light emitting elements (R, G, B) that emit red (R), green (G), and blue (B) on a common substrate 1. An example is shown. FIG. 1 is a longitudinal sectional view of a light emitting element (R, G, B), and FIG. 2 is a plan view. In an actual display device, a large number of light emitting elements (R, G, B) are arranged on the substrate 1 to form a display area, and passive driving or element-by-element is performed by a driving circuit arranged outside the display area (not shown). Also, the drive circuit is arranged and is actively driven.

  As shown in FIG. 1, the light emitting device (R, G, B) according to the present embodiment has an anode 2 as a first reflecting member, an organic layer 3, and a cathode 4 as a second reflecting member stacked on a substrate. This is a so-called top emission structure in which light emission is extracted from the film formation surface side. These RGB light emitting elements are partitioned by a partition wall 5 called a bank. In some cases, an organic layer or an inorganic layer such as a sealing film is further laminated on the cathode 4. Furthermore, although illustration is omitted, a film or a substrate for preventing external light reflection may be further laminated.

  The anode 2 has a two-layer structure of a reflective electrode 21 and a transparent electrode 22. As a material in contact with the hole injection layer 31 of the anode 2, a material having a high work function is used. Specifically, as the material of the reflective electrode 21, for example, a metal such as Al, Cr, Mo, Ni, Pt, Au, or Ag, an alloy containing them, an intermetallic compound, or the like can be used. The thickness of the reflective electrode 21 is 100 nm, for example. The reflective electrode 21 preferably has a high reflectance with an average reflectance of 80% or more with respect to light having a wavelength of 400 to 700 nm. Further, as the material of the transparent electrode 22, for example, a metal oxide such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) can be used. The thickness of the transparent electrode 22 is, for example, 75 nm. Although not shown in FIGS. 1 and 2, a lead electrode (wiring electrode) is connected to the anode 2. The anode 2 may have a single layer structure of the reflective electrode 21.

  The organic layer 3 may be partially composed of an inorganic material. Further, the number of layers can be reduced by dividing the layers into multiple layers or by having a single layer function as a plurality of layers. The organic layer 3 shown in FIG. 1 has a multilayer structure in which a hole injection layer 31, a hole transport layer 32, a light emitting layer 33, and an electron transport layer 34 are stacked in this order from the anode 2 side. The organic layer 3 only needs to have at least the light emitting layer 33. However, in order to efficiently promote the electroluminescence phenomenon, a hole injection layer 31, a hole transport layer 32, an electron transport layer 34, and the like may be disposed. preferable.

  In the case of a resonator structure, each RGB light emitting element has a preferable resonator optical path length. In the case of the structure of FIG. 1, the separation distance between the reflecting surface of the reflecting electrode 21 and the cathode 4 is the resonator optical path length. As an example, the laminated film thickness for obtaining a preferable resonator optical path length of red (R) is 300 nm, the laminated film thickness for obtaining a preferable resonator optical path length of green (G) is 235 nm, and blue (B ) To obtain a preferable resonator optical path length is 200 nm. These resonator optical path lengths are adjusted by the film thickness of the organic layer 3, for example. However, as described above, it is difficult to completely prevent the film thickness from deviating from the design value in the manufacturing process. In particular, it is difficult to control the film thickness when the organic layer 3 is formed by a coating method. For example, when the film is formed by an inkjet method, there may be a variation in film thickness of 5% or more between elements.

  The structure shown in FIG. 1 adjusts the resonator optical path length by changing the thickness of the hole injection layer 31 as an example. Specifically, the thickness (design value) of the red (G) hole injection layer 31 is 125 nm, for example, and the thickness (design value) of the green (G) hole injection layer 31 is 65 nm, for example, blue. The thickness (design value) of the hole injection layer 31 in (B) is, for example, 20 nm. The hole transport layer 32, the light emitting layer 33, and the electron transport layer 34 have the same thickness in the RGB resonator structure. The thickness (design value) of the hole transport layer 32 is, for example, 30 nm, the thickness (design value) of the light emitting layer 33 is, for example, 30 nm, and the thickness (design value) of the electron transport layer 34 is, for example, 40 nm.

The hole injection layer 31 and the hole transport layer 32 may be formed of a material having a high hole transport property. Examples thereof include phthalocyanine compounds such as copper phthalocyanine (CuPc) and starburst amines such as m-MTDATA. Aromatic polymers such as 4,4'-bis [N- (1-naphthyl) -N-phenylamino] -biphenyl (NPB) and N-phenyl-p-phenylenediamine (PPD) Tertiary amine, stilbene compounds such as 4- (di-P-tolylamino) -4 ′-[4- (di-P-tolylamino) styryl] stilbenzene, triazole derivatives, styrylamine compounds, buckyballs, C _{60 and the} like Organic materials such as fullerene are used. Further, a polymer dispersion material in which a low molecular material is dispersed in a polymer material such as polycarbonate may be used. However, it is not limited to these materials.

As the light emitting layer 33, a material that generates an electroluminescence phenomenon of red (R), green (G), and blue (B) can be used. Examples of the material of the light-emitting layer 33 include fluorescent organometallic compounds such as (8-hydroxyquinolinato) aluminum complex (Alq ₃ ), 4,4′-bis (2,2′-diphenylvinyl) -biphenyl ( Aromatic dimethylidin compounds such as DPVBi), styrylbenzene compounds such as 1,4-bis (2-methylstyryl) benzene, 3- (4-biphenyl) -4-phenyl-5-t-butylphenyl-1,2, Fluorescent organic materials such as triazole derivatives such as 4-triazole (TAZ), anthraquinone derivatives and fluorenol derivatives, polymer materials such as polyparafinylene vinylene (PPV), polyfluorene and polyvinylcarbazole (PVK), platinum complexes And phosphorescent organic materials such as iridium complexes can be used. However, it is not limited to these materials. In addition, the organic material may not be used, and an inorganic material that generates an electroluminescence phenomenon may be used.

The electron transport layer 34 only needs to be formed of a material having high electron transport properties. For example, organic materials such as silacyclopentadiene (silole) derivatives such as PyPySPyPy, nitro-substituted fluorenone derivatives, and anthraquinodimethane derivatives , Metal complexes of 8-quinolinol derivatives such as tris (8-hydroxyquinolinate) aluminum (Alq ₃ ), metal phthalocyanine, 3- (4-biphenyl) -5- (4-t-butylphenyl) -4-phenyl Triazole compounds such as -1,2,4-triazole (TAZ), and oxa compounds such as 2- (4-biphenylyl) -5- (4-t-butyl) -1,3,4-oxadiazol (PBD) Use fullerenes such as diazole compounds, buckyballs, C ₆₀ , and carbon nanotubes be able to. However, it is not limited to these materials.

  As the material of the cathode 4, a material having a low work function in a region in contact with the electron transport layer 34 and a small loss of reflection and transmission of the entire cathode can be used. Specifically, as the material of the cathode 4, a metal such as Al, Mg, Ag, Au, Ca, Li or a compound thereof, or an alloy containing them can be used as a single layer or a stacked layer. In addition, thin lithium fluoride or lithium oxide may be formed in a region in contact with the electron transport layer 34 to control the electron injection characteristics. The thickness of the cathode 4 is 10 nm, for example. As described above, the present embodiment has a top emission structure that outputs light from the film formation surface side, that is, the cathode side. Accordingly, the cathode 4 is a semi-transparent electrode having an average transmittance of 20% or more with respect to light having a wavelength of 400 to 700 nm. The transmittance can be adjusted by, for example, the film thickness of the electrode. Although not shown in FIGS. 1 and 2, a lead electrode (wiring electrode) is connected to the cathode 4.

  When a sealing film is further laminated on the cathode 4, it can be formed of a transparent inorganic material having a low water vapor or oxygen transmittance, for example. As an example of the material for the sealing film, silicon nitride (SiNx), silicon nitride oxide (SiOxNy), aluminum oxide (AlOx), aluminum nitride (AlNx), or the like can be used.

  As an example of the material of the partition wall 5 called a bank, a photosensitive resin containing a fluorine component can be used. By containing a fluorine component, liquid repellency can be exhibited with respect to a liquid material, and thus liquid flow (so-called overlap) can be suppressed when a film is formed using a coating method. Furthermore, it is preferable to form the partition part 5 with the material which has light-shielding property.

  Here, the luminance in the front direction of the blue (B) and red (R) light emitting elements is likely to be an unacceptable luminance fluctuation due to the increase or decrease in the visibility due to the shift of the peak wavelength, as compared with the green (G) light emitting elements. . Among these, blue (B) has a larger luminance variation with respect to the variation of the resonator optical path length than red (R). Therefore, in the present embodiment, for the blue (B) light emitting element, even if the film thickness deviates from the design value in the manufacturing process and the resonator optical path length increases or decreases, the luminance in the front direction fluctuates. Suppress. As a structure for this purpose, the internal emission spectrum, the relative visibility spectrum, and the resonator output spectrum satisfy the following conditions. The internal emission spectrum corresponds to the photoluminescence (PL) spectrum of the light emitting material. The resonator output spectrum corresponds to the spectrum of light transmitted from the resonator structure. On the other hand, the wavelength that becomes the maximum value of the specific luminous efficiency spectrum is 555 nm in the photopic standard.

  That is, as shown in FIG. 3, the resonator output spectrum is between the peak wavelength (λS1) of the internal emission spectrum S1 and the peak wavelength (ie, 555 nm) of the relative visibility spectrum which is not shown because it is known. The peak wavelength (λS2) of S2 is positioned. For convenience of explanation, the wavelength at which the emission intensity is maximum may be referred to as a peak wavelength.

  As described above, in the case of the structure shown in FIG. 1, since the laminated film thickness (design value) of the organic layer 3 for making the resonator optical path length preferable for blue (B) is determined, the resonance is performed accordingly. The peak wavelength (target value) of the instrument output spectrum S2 is also determined. For example, the peak wavelength (target value) when the resonator optical path length (design value) is 200 nm is 470 nm. Moreover, the peak wavelength of the specific luminous sensitivity spectrum is 555 nm in the photopic standard. Therefore, in the present embodiment, the light emitting material that exhibits the internal emission spectrum S1 having the spectrum in the above positional relationship is selected from, for example, the above-described light emitting materials, and the light emitting layer 33 is formed using the light emitting material. To do. That is, as an example, a light emitting layer exhibiting a desired spectrum can be used from the light emitting materials described above. Preferably, the light emitting material has a peak wavelength of the internal emission spectrum S1 in the range of 450 nm to 480 nm, and the peak wavelength of the resonator output spectrum S2 is longer than the peak wavelength of the internal emission spectrum S1. To be located. Further, it is preferable that the slope shape on the long wavelength side of the internal emission spectrum S1 is substantially proportional to the inverse of the slope on the short wavelength side of the relative luminous sensitivity spectrum. In particular, in the case of blue (B), it is preferable that the long wavelength side of the internal emission spectrum S1 is steep and the peak wavelength of the resonator output spectrum S2 is located in the steep region.

As a more preferable example, as shown in FIG. 4 and FIG. 5, the rate of change R _E of the emission intensity of the internal emission spectrum S1 at the peak wavelength (λS2) of the resonator output spectrum S2 is −0.03 [1 / nm]. Hereinafter, it is preferably set to −0.05 [1 / nm] or less. Figure 4 shows the results of the peak wavelength λS2 has simulated the relation between 470nm the rate of change R _E of the emission intensity, luminance change rate RL (%) with respect to the film thickness fluctuation of the time (design value). FIG. 5 shows a result of simulating a change in front luminance when, for example, the film thickness of the light emitting layer 33 increases or decreases near the design value. In FIG. 5, as an example, the change rate R _E among the plot points in FIG. 4 is −0.017 [1 / nm], −0.034 [1 / nm], −0.054 [1 / nm]. The simulation result is shown.

The change rate R _E of the emission intensity is obtained by dividing the gradient of the internal emission spectrum S1 at the peak wavelength (λS2) of the resonator output spectrum S2 by the emission intensity of the wavelength (λS2), and R _E [1 / Nm] = [dE (λS2) / dλ] / E (λS2). The luminance change rate RL (%) is a luminance change rate with respect to a film thickness deviation of d0 ± 2 nm, where d0 is an optimum film thickness that satisfies NTSC color purity. More specifically, it is a value calculated by the luminance change rate RL [%] = [difference between maximum and minimum luminance at d0 ± 2 nm] / [luminance at d0] × 100. As can be seen from FIGS. 4 and 5, the change rate R _E of the emission intensity in the light-emitting element of blue (B) is to a -0.03 [1 / nm] or less effect of suppressing the luminance change is starting to occur Is preferable, and it is more preferable to set it to −0.05 [1 / nm] or less, in which luminance fluctuation can be strongly suppressed.

In the present embodiment, it is preferable that the change rate R _E of the emission intensity of the internal light emission spectrum S1 at the peak wavelength λS2 of the resonator output spectrum S2 satisfies the above condition, the rate of change R _E is that the condition is satisfied in addition, or the rate of change R _E is in place that satisfies the above condition may be set so as to satisfy the conditions shown in FIG. That is, at the skirt on the long wavelength side of the internal emission spectrum S1, between wavelengths (λ90 to λ50) corresponding to the range of 90% to 50% of the maximum value of the emission intensity of the internal emission spectrum S1 (the range of the solid line in FIG. 6). The peak wavelength λS2 of the resonator output spectrum S2 is set.

  In order to satisfy the various conditions described above, the control is not limited to the selection of the light emitting material. For example, the peak wavelength (target value) of the resonator output spectrum S2 is adjusted within a range where the color purity is allowed. You may make it become a relationship. The peak wavelength (target value) of the resonator output spectrum S2 can be adjusted by adjusting the film thickness (design value) of the organic layer 3. Furthermore, you may make it satisfy | fill the said conditions by both selection of a luminescent material, and adjustment of the film thickness (design value) of the organic layer 3. FIG.

  The resonator structure can be designed with a relatively large color purity. On the other hand, the luminance of the blue (B) or red (R) light emitting element may result in unacceptable luminance fluctuation due to the shift of the peak wavelength of the resonator output spectrum S2. For example, when the film thickness (corresponding to the optical path length) corresponding to the distance between the mirrors changes by about 5 nm (about 5% of the total device film thickness), the peak wavelength may change by about 5 nm. For example, in the case of a blue light-emitting element, when the design value of the peak wavelength is set to 470 nm and the film thickness increases by 5 nm, the visibility at the shifted peak wavelength (for example, 475 nm) changes by 20% or more, resulting in a large luminance change and thus a decrease in image quality. (Brightness unevenness).

  That is, the cause of the deterioration in image quality (luminance unevenness) in the front direction is the relationship between the shift of the peak wavelength of the resonator output spectrum S2 and the relative visibility spectrum. In this embodiment, the peak of the internal emission spectrum S1 is used. The peak wavelength of the resonator output spectrum S2 is positioned between the wavelength and the peak wavelength of the relative luminous sensitivity spectrum (that is, the photopic standard of 555 nm). In this way, when the peak wavelength (λS2) of the resonator output spectrum S2 shifts to the high visibility side due to manufacturing errors, the light emission output decreases, and conversely, the peak wavelength (λS2) falls to the low visibility side. In the case of shifting, the light emission output is increased, whereby the luminance fluctuation in the front direction can be suppressed. When actually simulating, in the case of blue (B), the luminance fluctuation in the front direction when the peak wavelength (λS2) of the resonator output spectrum S2 is shifted within the range of ± 2 nm is approximately within ± 5%. Have confirmed.

  In the light-emitting element shown in FIG. 1, the first and second reflecting members are constituted by the reflecting electrode and the semi-transmissive electrode, but the present invention is not limited to this, and a reflecting film different from the electrode is used. You may make it form. In this case, the anode and the cathode on the element side of the reflective film different from the electrode are preferably transparent electrodes.

(Second Embodiment)
The present embodiment is a modification of the first embodiment, and is an embodiment in which a red (R) light emitting element is used instead of a blue (B) light emitting element.

  That is, in the case of a red (R) light emitting element, as shown in FIG. 7, a resonator is provided between the peak wavelength (λS1) of the internal emission spectrum S1 and the peak wavelength (ie, 555 nm) of the relative luminous sensitivity spectrum. The peak wavelength (λS2) of the output spectrum S2 is positioned.

  As described above, in the case of the structure shown in FIG. 1, the layer thickness (design value) of the organic layer 3 for determining the resonator optical path length preferable for red (R) is determined. The peak wavelength (target value) of the instrument output spectrum S2 is also determined. For example, the peak wavelength (target value) when the resonator optical path length (design value) is 300 nm is 620 nm. Moreover, the peak wavelength of the specific luminous sensitivity spectrum is 555 nm in the photopic standard. Therefore, in the present embodiment, the light emitting material that exhibits the internal emission spectrum S1 having the spectrum in the above positional relationship is selected from, for example, the above-described light emitting materials, and the light emitting layer 33 is formed using the light emitting material. To do. Preferably, the light emitting material has a peak wavelength of the internal emission spectrum S1 in the range of 600 nm to 640 nm, and the peak wavelength of the resonator output spectrum S2 is shorter than the peak wavelength of the internal emission spectrum S1. To be located. Furthermore, it is preferable that the slope shape on the short wavelength side of the internal emission spectrum S1 is substantially proportional to the inverse of the slope on the long wavelength side of the relative luminous sensitivity spectrum. In particular, in the case of red (R), the peak wavelength of the resonator output spectrum S2 is preferably located in a region where the emission intensity at the rising edge on the short wavelength side of the internal emission spectrum S1 changes sharply.

More preferred examples are 4 and by 5 simulation results similar reasons, the resonator change rate R _E of the emission intensity of the internal light emission spectrum S1 at the peak wavelength (λS2) of the output spectrum S2 is +0.03 [1 / Nm] or more, preferably +0.05 [1 / nm] or more.

Further, in the present embodiment, it is preferable that the rate of change R _E of the emission intensity of the internal emission spectrum S1 at the peak wavelength λS2 of the resonator output spectrum S2 satisfies the above condition, but the rate of change R _E satisfies the above condition. in particular, in addition, or the rate of change R _E is in place that satisfies the above condition may be set so as to satisfy the conditions shown in FIG. That is, at the skirt on the short wavelength side of the internal emission spectrum S1, between wavelengths (λ95 to λ50) corresponding to the range of 95% to 50% of the maximum value of the emission intensity of the internal emission spectrum S1 (the range of the solid line in FIG. 8). The peak wavelength λS2 of the resonator output spectrum S2 is set.

  Further, as in the case of blue (B), in order to satisfy the above conditions, the selection is not limited to the selection of the light emitting material. For example, the peak wavelength (target) of the resonator output spectrum S2 within the allowable range of color purity. (Value) may be adjusted so as to satisfy the above relationship. The peak wavelength (target value) of the resonator output spectrum S2 can be adjusted by adjusting the film thickness (design value) of the organic layer 3. Furthermore, you may make it satisfy | fill the said conditions by both selection of a luminescent material, and adjustment of the film thickness (design value) of the organic layer 3. FIG.

  Thus, even when the target is a red (R) light emitting element, it is between the peak wavelength of the internal emission spectrum S1 and the peak wavelength of the relative luminous efficiency spectrum (that is, the photopic standard 555 nm). In addition, by setting the peak wavelength of the resonator output spectrum S2 to be located, when the peak wavelength (λS2) of the resonator output spectrum S2 shifts to the high visibility side due to a manufacturing error, the light emission output decreases, on the contrary In addition, when the peak wavelength (λS2) shifts to the low visibility side, the light emission output increases, thereby suppressing the luminance fluctuation in the front direction. When actually simulating, as shown in FIG. 9, in the case of red (R), the luminance fluctuation in the front direction when the peak wavelength of the resonator output spectrum S2 is shifted within the range of ± 2 nm is within ± 5%. It is confirmed that.

(Third embodiment)
The first embodiment targets a blue (B) light emitting element, and the second embodiment targets a red (R) light emitting element. However, a display device in which a display region is formed by a large number of RGB light emitting elements can include both the blue (B) and red (R) light emitting elements described in the first and second embodiments. Both (B) and red (R) luminance fluctuations can be suppressed.

(Fourth embodiment)
In the first to third embodiments, an example in which the thickness of the hole injection layer 31 is changed to adjust the RGB resonator optical path lengths has been described. However, the present invention is not limited to this, and as shown in FIG. 10, the RGB resonator optical path lengths may be adjusted by changing the thickness of the light emitting layer 33.

(Fifth embodiment)
Furthermore, in the first to fourth embodiments, the top emission structure light emitting element has been described as an example. However, the structure is not limited to this, and a bottom emission structure may be used as shown in FIG. FIG. 11 shows an example of a bottom emission structure in which the reflective electrode 21 of FIG. 1 is a transflective electrode and the cathode 4 is a reflective electrode. However, it is not limited to the structure of FIG.

(Sixth embodiment)
Then, an example is demonstrated about the procedure which manufactures the RGB light emitting element shown in FIG.
First, the reflective electrode 21 and the transparent electrode 22 are sequentially formed using, for example, vapor deposition or sputtering. The patterning of these electrodes 21 and 22 can be performed by, for example, a photolithography method. Next, for example, a photosensitive resin containing a fluorine component is applied onto the substrate 1 and dried to form a film, and then the partition wall portion 5 having a pattern as shown in FIG. 1 is formed by, for example, photolithography. For example, in the case of a passive type, the partition walls 5 are formed after the electrodes 21 and 22 are formed in a stripe shape. On the other hand, in the case of the active type, for example, the partition walls 5 are formed after the electrodes 21 and 22 are formed in an island shape connected to each drive circuit.

  Next, the liquid material of the hole injection layer 32 is applied to the region partitioned by the partition wall 5 using, for example, an inkjet nozzle, and dried to form a film. Similarly, the hole transport layer 32 and the light emitting layer 33 are formed by coating each element by a coating method. The film thickness can be adjusted by, for example, the amount of liquid material applied. Next, the electron transport layer 34 and the cathode 4 are formed in order using a vapor deposition method. Patterning of the cathode 4 can be performed using a mask such as a metal mask or using the bank shape of the partition wall 5. For example, in the case of a passive type, the cathode 4 can be patterned in a stripe shape. On the other hand, for example, in the case of an active type, a so-called solid electrode can be formed without patterning. Through such a procedure, the RGB light emitting device shown in FIGS. 1 and 2 can be manufactured.

  As described above, according to the first to sixth embodiments, in the light emitting element having the resonator structure, the resonator output spectrum is between the peak wavelength of the internal emission spectrum and the peak wavelength of the relative luminous sensitivity spectrum. By setting the peak wavelength of the light source to be located, it is possible to suppress the luminance fluctuation caused by the variation in the resonator optical path length. In other words, even if the film thickness deviates from the design value, the luminance fluctuation is small, so that the film thickness variation can be allowed to some extent, and the yield can be improved and the cost can be reduced.

  The technology according to the above embodiment can be applied to an inorganic thin film light emitting element (electroluminescence, light emitting diode) having a laminated element structure in addition to an organic thin film light emitting element. Further, the present invention can be applied to a light-emitting display device in which light-emitting elements are arrayed on a surface. Moreover, the structure which takes out light emission from both the 1st and 2nd reflective member may be sufficient. Furthermore, it is not limited to three colors of RGB, and may include one color, two colors, or other colors.

  Although the present invention has been described in detail with reference to specific embodiments, various substitutions, modifications, changes, etc. in form and detail are defined in the claims. It will be apparent to those skilled in the art that this can be done without departing from the spirit and scope. Therefore, the scope of the present invention should not be limited to the above-described embodiments and the accompanying drawings, but should be determined based on the description of the claims and equivalents thereof.

Claims (10)

A first reflective member; a second reflective member; and a light emitting layer disposed between the first reflective member and the second reflective member, wherein the first reflective member and the second reflective member resonate. A resonator structure that transmits a part of the light to be transmitted through the first reflecting member or the second reflecting member;
The wavelength that becomes the maximum value of the resonator output spectrum from the resonator structure is located in the range of 90% to 50% of the emission intensity that becomes the maximum value of the internal emission spectrum of the light emitting layer,
The light emitting element characterized in that the wavelength which becomes the maximum value of the internal emission spectrum is in the range of 450 nm to 480 nm. The wavelength that is the maximum value of the resonator output spectrum is
The light-emitting element according to claim 1, wherein the light-emitting element is positioned on a long wavelength side with respect to a wavelength that is a maximum value of the internal emission spectrum. The light emitting device according to claim 2, the change rate R _E of the emission intensity of the internal light emission spectrum at the wavelength of maximum value of the resonator output spectrum is equal to or is -0.03 or less. The light emitting device according to claim 3, the change rate R _E of the luminous intensity is equal to or is -0.05 or less.   5. The luminance variation in the front direction when the wavelength that is the maximum value of the resonator output spectrum is shifted within a range of ± 10 nm is within ± 5%. 6. The light emitting element of description. A first reflective member; a second reflective member; and a light emitting layer disposed between the first reflective member and the second reflective member, wherein the first reflective member and the second reflective member resonate. A resonator structure that transmits a part of the light to be transmitted through the first reflecting member or the second reflecting member;
The wavelength that becomes the maximum value of the resonator output spectrum from the resonator structure is located in the range of 95% to 50% of the emission intensity that becomes the maximum value of the internal emission spectrum of the light emitting layer,
The light emitting element characterized in that the wavelength which becomes the maximum value of the internal emission spectrum is in the range of 600 nm to 640 nm. The wavelength that is the maximum value of the resonator output spectrum is
The light-emitting element according to claim 6, wherein the light-emitting element is located on a short wavelength side with respect to a wavelength that is a maximum value of the internal emission spectrum. The light emitting device of claim 7, the change rate R _E of the emission intensity of the internal light emission spectrum at the wavelength of maximum value of the resonator output spectrum is characterized in that at +0.03 or more. The light emitting device of claim 8, the change rate R _E of the luminous intensity is equal to or is +0.05 or more.   The luminance variation in the front direction when the wavelength that is the maximum value of the resonator output spectrum is shifted within a range of ± 5 nm is within ± 10%. The light emitting element of description.