CN104868059A

CN104868059A - Light-emitting element and display apparatus

Info

Publication number: CN104868059A
Application number: CN201510145881.0A
Authority: CN
Inventors: 吉冈俊博; 内田敏治
Original assignee: Pioneer Corp
Current assignee: Pioneer Corp
Priority date: 2009-06-11
Filing date: 2009-06-11
Publication date: 2015-08-26
Anticipated expiration: 2029-06-11
Also published as: CN104868059B; CN104851986B; CN104851985B; CN104851985A; CN104851986A

Abstract

The invention relates to a light-emitting element with a resonator structure and a display apparatus. With the element and the apparatus, even when a design value of a film thickness contrast ratio is deviated, the brightness fluctuation can still be suppressed. The light-emitting element is provided with a resonator structure and a spectral band absorption filter. The resonator structure consists of a first reflection component, a second reflecting component, and a light-emitting layer arranged between the first reflection component and the second reflecting component; and the resonant light between the first reflection component and the second reflecting component passes through the first reflection component or the second reflecting component. The spectral band absorption filter transmits the light transmitted by the first reflection component or the second reflecting component. The spectral band absorption filter is presented with a transmitting curve, wherein the transmittance is reduced at the wavelength direction with the maximum light visual function value and the transmittance is increased after the minimum wavelength is reached and the transmittance is exceeded according to the transmitting curve; and the value of the curve is between the wavelength with the maximum resonator output spectrum of the resonator structure and the wavelength with the maximum light visual coefficient function.

Description

Light-emitting element and display device

The application is a divisional application of an invention patent application of an international application with the date of 2009, 06, 11 (international application number: PCT/JP2009/002646) entering the Chinese national stage (application number: 200980159844.8).

Technical Field

The invention relates to a light emitting element and a display device.

Background

EL elements are known as light-emitting elements in display devices such as display devices and lighting devices, and among them, materials that emit light by Electroluminescence (EL) phenomenon when a voltage is applied are used. The EL element is a thin-film light-emitting element in which a light-emitting layer of an organic material or an inorganic material is formed between an upper electrode and a lower electrode, and a voltage is applied to the light-emitting layer from the upper and lower electrodes to emit light.

In recent years, a light-emitting element having a resonator structure (so-called microcavity structure) has been developed, in which one of an upper electrode and a lower electrode is a total reflection mirror and the other is a semi-transmission mirror that transmits a part of wavelengths, thereby resonating light emitted from a light-emitting layer (see, for example, patent documents 1 and 2).

However, in the thin film light emitting element of the resonator structure, the color filter characteristic is sensitive to the distance between mirrors (resonator optical path length). Therefore, for example, if the optical path length of the resonator varies due to manufacturing errors during the manufacturing process, color coordinates (color purity) and luminance variations in the front direction occur, which cannot be tolerated.

In the resonator structure, a design having a large margin for color purity can be made. On the other hand, the luminance of the blue (B) and red (R) light-emitting elements varies beyond the allowable range due to the shift of the center wavelength. For example, if the film thickness (corresponding to the optical path length) corresponding to the distance between the mirrors changes by about 5nm (about 5% of the entire element film thickness), the center wavelength also changes by about 5 nm. For example, in the case of a blue light-emitting element, when the design value of the center wavelength is 470nm, if the film thickness is increased by 5nm, the luminous efficiency at the shifted center wavelength (e.g., 475nm) changes by 20% or more, resulting in a large luminance change and a reduction in image quality (luminance unevenness).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2002-373776

Patent document 2: japanese patent publication No. 2002-518803

Disclosure of Invention

The above is an example of the problem to be solved by the present invention. An object of the present invention is to provide a light emitting element and a display device having a resonance structure capable of suppressing luminance variation even if the film thickness is deviated from a design value and the optical path length of a resonator is changed.

The light-emitting element of the present invention is characterized by comprising a resonator structure and a spectral band absorption filter, wherein the resonator structure comprises 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 part of light resonating between the first reflecting member and the second reflecting member is transmitted through the first reflecting member or the second reflecting member, the spectral band absorption filter further absorbs a part of light transmitted through the first reflecting member or the second reflecting member, and a wavelength at which a transmission amount of the spectral band absorption filter reaches a minimum value is located between a wavelength at which a resonator output spectrum of the resonator structure reaches a maximum value and a wavelength at which a light visual effect function reaches a maximum value.

The display device of the present invention is characterized by comprising a plurality of resonator structures and a spectral band absorption filter common to the plurality of resonator structures, wherein the resonator structures comprise 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 part of light resonating between the first reflecting member and the second reflecting member is transmitted through the first reflecting member or the second reflecting member, the spectral band absorption filter further absorbs a part of light transmitted through the first reflecting member or the second reflecting member, and a wavelength at which a transmission amount of the spectral band absorption filter reaches a minimum value is located between a wavelength at which a resonator output spectrum of the resonator structure reaches a maximum value and a wavelength at which a light visual effect function reaches a maximum value.

Drawings

Fig. 1 is a longitudinal sectional view of an RGB light-emitting element in a first embodiment of the present invention.

Fig. 2 is a plan view of an RGB light-emitting element in the first embodiment of the present invention.

Fig. 3 is a diagram showing characteristics of the spectral band absorption filter when blue (B) is a target color.

Fig. 4 is a diagram showing characteristics of the spectral band absorption filter when blue (B) is a target color.

Fig. 5 is a graph showing a relationship between a film thickness and an emission spectrum in the light-emitting element.

Fig. 6 is a graph showing the relationship between the film thickness and the luminance in the light-emitting element.

Fig. 7 is a graph showing the relationship between the film thickness and the emission spectrum in the light-emitting element.

Fig. 8 is a graph showing the relationship between the film thickness and the luminance in the light-emitting element.

Fig. 9 is a graph showing a relationship between a film thickness and an emission spectrum in the light-emitting element.

Fig. 10 is a graph showing the relationship between the film thickness and the luminance in the light-emitting element.

Fig. 11 is a graph showing a relationship between an absorption change rate and a luminance change rate of the band absorption filter in the light-emitting element.

Fig. 12 is a diagram showing characteristics of the spectral absorption filter when red (R) is a target color.

Fig. 13 is a diagram showing characteristics of the spectral absorption filter when red (R) is a target color.

Fig. 14 is a longitudinal sectional view of a light-emitting element according to a fourth embodiment of the present invention.

Fig. 15 is a longitudinal sectional view of a light-emitting element according to a fifth embodiment of the present invention.

Description of the 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 wall parts

6 spectral band absorption filter

7 Filter support substrate

Detailed Description

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

(first embodiment)

In the example shown in fig. 1 and 2, 3 light-emitting elements (R, G, B) emitting red (R), green (G), and blue (B) light are disposed on a common substrate 1 to form an RGB cell. Fig. 1 is a longitudinal sectional view of the light emitting element (R, G, B), and fig. 2 is a plan view. In an actual display device, a plurality of light-emitting elements (R, G, B) are arranged on a substrate 1 to form a display region, and the display region is driven passively by a driving circuit (not shown) arranged outside the display region or is driven actively by a driving circuit arranged for each element.

As shown in fig. 1, the light-emitting element (R, G, B) of the present embodiment has a so-called top emission (top emission) structure in which an anode 2 as a first reflecting member, an organic layer 3, and a cathode 4 as a second reflecting member are stacked on a substrate, and light is emitted from the surface side on which a thin film is formed. These RGB light emitting elements are separated by partition walls 5 called banks (banks). An organic layer or an inorganic layer such as a sealing film may be stacked on the cathode 4.

Further, a spectral band absorption filter (BEF)6 is disposed at a position facing the film formation surface for emitting light, and selects a wavelength for light emitted from the resonator structure to transmit a part of the light. The spectral band absorbing filter 6 preferably shares a filter with each of the RGB light-emitting elements as shown in fig. 1. The spectral band absorption filter 6 is supported by a filter support member fixedly arranged on the support member. In the example shown in fig. 1, the filter support member is constituted by, for example, a substrate (filter support substrate) 7, and the substrate 7 is formed of a transparent material. The filter support member is not limited to the substrate, and may be a transparent film. For example, a structure or a material for preventing reflection of external light may be added.

The anode 2 has a two-layer structure including a reflective electrode 21 and a transparent electrode 22. A material having a high work function is used as the material of the anode 2 in contact with the hole injection layer 31. Specifically, as a material of the reflective electrode 21, for example, a metal such as Al, Cr, Mo, Ni, Pt, Au, Ag, or an alloy or intermetallic compound containing these metals can be used. The thickness of the reflective electrode 21 is, for example, 100 nm. The average value of the reflectance of the reflective electrode 21 with respect to light having a wavelength of 400 to 700nm is 80% or more, and a high reflectance is preferable. 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 fig. 1 and 2, an extraction electrode (wiring electrode) is connected to the anode 2. The anode 2 may have a single-layer structure having the reflective electrode 21.

In the organic layer 3, a part of the layers may be made of an inorganic material. The number of layers may be further divided to have more layers, or a single layer may function as a plurality of layers to reduce the number 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 may have at least the light-emitting layer 33, but in order to effectively promote the generation of the electroluminescence phenomenon, it is preferable to dispose the hole injection layer 31, the hole transport layer 32, the electron transport layer 34, and the like.

When the resonator structure is formed, the respective light emitting elements of RGB have the optimum resonator optical path length. In the configuration of fig. 1, the distance between the reflective electrode 21 and the reflective surface of the cathode 4 is the resonator optical path length. For red (R), the laminated film thickness was set to 300nm to obtain an optimum resonator optical path length, as an example; for green (G), the laminated film thickness was set to 235nm to obtain the optimum resonator optical path length; for blue (B), the laminated film thickness was set to 200nm in order to obtain an optimum resonator optical path length. The optical path length of the resonator is adjusted by adjusting 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 during the manufacturing process. Particularly, when the organic layer 3 is formed by a coating method, it is difficult to control the film thickness. When the film is formed by, for example, an ink jet method, the variation in film thickness among the elements becomes 5% or more.

In the structure shown in fig. 1, the optical path length of the resonator is adjusted by changing the thickness of the hole injection layer 31, for example. Specifically, the thickness (design value) of the hole injection layer 31 for red (R) was 125 nm; the thickness (design value) of the hole injection layer 31 for green (G) was 65 nm; the thickness (design value) of the hole injection layer 31 for blue (B) was 20 nm. In the resonator structure of RGB, the thicknesses of the transport layer 32, the light-emitting layer 33, and the electron transport layer 34 are the same. For example, the thickness (design value) of the hole transport layer 32 is 30 nm; the thickness (design value) of the light-emitting layer 33 was 30 nm; the thickness (design value) of the electron transport layer 34 was 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, and examples thereof include phthalocyanine compounds such as copper phthalocyanine (CuPc), star (starburst) amines such as m-MTDATA, polymers of benzidine amines, and 4,4' -bis [ N- (1-naphthyl) -N-anilino group]-biphenyl (4, 4' -bis [ N- (1-naphthyl) -N-phenylaminono)]-biphenyl: NPB), N-phenyl-p-phenylenediamine (N-phenyl-p-phenylenediamine: PPD), 4- (di-p-tolylamino) -4' - [4- (di-p-tolylamino) styryl]Stilbene (4- (di-P-tolylimine) -4' - [4- (di-P-tolylimine) styryl]stilbene (stilbene) compounds such as styrylbenzene), triazole derivatives, styrylamine compounds, buckyballs, and C₆₀And organic materials such as fullerene. A polymer dispersion material in which a low molecular material is dispersed in a polymer material such as polycarbonate can also be used. But is not limited to the above materials.

The light-emitting layer 33 may be formed of a material that causes red (R), green (G), and blue (B) electroluminescence. As the material of the light-emitting layer 33, for example, (8-hydroxyquinoline) aluminum complex (Alq) can be used₃)((8-hydroxyquinolinate)aluminum)complex(Alq₃) Fluorescent organic metal compounds such as); aromatic dimethylene compounds such as 4,4' -bis (2, 2-distyryl) -biphenyl (4, 4' -bis (2,2 ' -diphenylvinyl) -biphenol: DPVBi); styryl benzene compounds such as (1,4-bis (2-methylstyrene) benzene, 3- (4-biphenyl) -4-phenyl-5-tert-butylphenyl-1, 2,4-triazole (3- (4-biphenyl) -4-phenyl-5-t-butylphenyl-1,2, 4-triazole: TAZ), a triazole (triazole) derivative such as anthraquinone (anthraquinone) derivative and fluorene (fluorone) derivative, a fluorescent organic material such as polyethylene terephthalate (polyparaphenylene vinylene: PPV), polyfluorene (polyfluorene), polyvinylcarbazole (polyvinylcarbazole: PVK) based polymer materials; the organic material is not limited to the above-mentioned materials, and an inorganic material which can cause an electroluminescence phenomenon may be used instead of the organic material.

The electron transport layer 34 may be formed of a material having high electron transport properties, for exampleOrganic materials such as silacyclopentadiene (silole) derivatives such as pyyspypypy, nitrofluorenone (nitro-substituted fluoronone) derivatives, anthraquinone dimethane (anthraquinone) derivatives, and the like; tris (8-hydroxyquinolinato) aluminum (tris (8-hydroxyquinolinato) aluminum: Alq₃) Metal complexes of 8-hydroxyquinoline (8-quinolinole) derivatives, etc.; metal phthalocyanine (metal phthalocyanine), triazole derivatives such as 3- (4-biphenyl) -5- (4-t-butylphenyl) -4-phenyl-1,2,4-triazole (3- (4-biphenyl) -5- (4-t-butylphenyl) -4-phenyl-1,2, 4-triazole: TAZ), oxadiazole derivatives such as 2- (4-biphenyl) -5- (4-t-butyl) -1,3,4-oxadiazole (2- (4-biphenyl) -5- (4-t-butyl) -1,3, 4-oxadiazole: PBD), buckyball, Cb, C, and B₆₀And fullerenes such as carbon nanotubes (cnts). But is not limited to the above 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 having a small overall reflection and transmission loss of the cathode can be used. Specifically, the cathode 4 may be formed as a single layer or stacked layers using a metal such as Al, Mg, Ag, Au, Ca, or Li, a compound thereof, or an alloy containing the above metal. In addition, thin lithium fluoride, lithium oxide, or the like can be formed in a region in contact with the electron transport layer 34 to control the electron injection property. The thickness of the cathode 4 is, for example, 10 nm. As described above, in this embodiment, a top emission structure is used in which light is emitted on one side of the deposition surface, i.e., on the cathode side. Therefore, the cathode 4 is a semi-permeable electrode, and has an average transmittance of, for example, 20% or more with respect to light having a wavelength of 400 to 700 nm. The transmittance can be adjusted by, for example, the thickness of the electrode. Although not shown in fig. 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 may be formed of, for example, a transparent inorganic material having a small permeability to water vapor and oxygen. As a material of the sealing film, for example, silicon nitride (SiN) can be used_x) Silicon oxynitride (SiO)_xN_y) Aluminum oxide (AlO)_x) Aluminum nitride (AlN)_x) And the like.

As a material of the bank partition wall 5, for example, a photosensitive resin containing a fluorine component can be used. Since the fluorine-containing polymer can act as a liquid repellent to a liquid material, a liquid flow (so-called overlap) can be suppressed when a film is formed by a coating method. The partition wall 5 is preferably formed of a material having light-shielding properties.

The spectral band absorption filter (BEF)6 may use, for example, a single spectral band absorption filter having an absorption characteristic of an approximate gaussian shape. The shape and material of the spectral band absorption filter 6 are not limited as long as the filter has absorption characteristics described below. For example, the spectral band absorption filter 6 may be a film or plate filter attached to the display surface, or may be a filter formed by applying or attaching a pigment having absorption characteristics described later to the display surface. However, since the filter is a single-band absorption filter, the absorption characteristics of the filter differ depending on which of blue (B), red (R), and green (G) is the target color. In the following description, a preferred example of the case where blue (B) is used as the target color will be described. In the description, for convenience of description, the wavelength at which the emission intensity is maximum is referred to as the center wavelength.

As shown in fig. 3, when blue (B) is the target color, the center wavelength (λ B) of the output spectrum of the resonator structure (hereinafter referred to as "resonator output spectrum") S1 is 470nm ± 10 nm. It has a width of ± 10nm because the central wavelength (λ B) required for NTSC color purity depends on the width and PL shape of the resonator output spectrum S1. In addition, the offset width of the center wavelength (λ B) due to film thickness unevenness is also considered. On the other hand, the center wavelength of the spectrum of the luminous efficacy function is 555nm under the photopic standard. In this case, in the preferred example of the present embodiment, the spectral band absorption filter 6 having the transmission spectrum S2 is used, and the absorption center wavelength (λ a) of the spectrum S2 is 495nm, for example. More preferably, the peak absorption is 60% or more when the bottom absorption is 0%. Fig. 3 shows a spectrum (hereinafter referred to as emission output spectrum) S3 of light output through the spectral band absorption filter 6 when the film thickness is formed to match the design value.

The absorption spectrum S2 of the spectral band absorption filter 6 is close to the resonator output spectrum S1, and the absorptance monotonically increases toward the long wavelength side from the center wavelength (λ B) of the resonator output spectrum S1. Further, as an important factor, it is preferable that the change in transmittance in the vicinity of the center wavelength of the resonator output spectrum S1 is sufficiently suppressed to the extent that the luminance variation can be sufficiently suppressed. Specifically, as shown in fig. 4, when the transmittance at the center wavelength (λ B) is T (0) and the transmittance at a wavelength of +10nm from the center wavelength is T (10), the ratio Δ T [ ═ T (10)/T (0) ] of the transmittances is preferably 0.9 or less, more preferably 0.7 or less, and still more preferably 0.6 or less.

As described above, the present embodiment further absorbs a part of the light output from the resonator structure by using the spectral band absorption filter 6 satisfying the above absorption conditions. That is, the shape in the vicinity of the center wavelength (λ B) is controlled by the spectral band absorption filter 6 so that the light emission output decreases when the center wavelength (λ B) of the resonator output spectrum S1 shifts to the high luminous efficiency side (480 nm), and increases when the center wavelength (λ B) shifts to the low luminous efficiency side (460 nm). With the above configuration, even when the film thickness varies within a range of ± 10nm of the design value, for example, and the optical path length of the resonator varies, the luminance variation can be suppressed. In this case, the deviation Δ u 'v' from the chromaticity coordinates to the color purity of NTSC is within 0.05, or the chromaticity coordinates to expand the color reproduction range of NTSC satisfy the condition of good color purity for color display.

The effect of suppressing the luminance variation will be described below with reference to a specific calculation result. The following calculation results are merely examples, and do not limit the present embodiment.

For example, assuming that the design value of the center wavelength (λ B) of the resonator output spectrum S1 is 472nm, fig. 5(a) shows the calculation result when the film thickness deviates from the design value of-1 nm. FIG. 5(b) shows the calculation results when the film thickness satisfies the design value. FIG. 5(c) shows the calculation results when the film thickness deviates from the design value of +1 nm. The spectral band absorption filter 6 used has an absorption characteristic of an approximately gaussian shape having an absorption center wavelength (λ a) of 500nm and an absorption coefficient σ of 10 nm. The ratio Δ T [ ═ T (10)/T (0) ] of the transmittance was about 0.9.

In each spectrum shown in fig. 5, spectrum S10 is the transmission spectrum of the spectral band absorption filter 6, and spectrum S11 is the emission output spectrum output by the spectral band absorption filter 6. Spectrum S12 is the emission output spectrum when the spectral band absorption filter 6 is not provided for comparison. Spectrum S13 is an internal light emission spectrum when light is emitted without using a resonator structure, i.e., a photoluminescence spectrum.

Further, fig. 6 shows the results of calculating the front luminance change when the film thickness changes around the design value.

As shown in the calculation results of fig. 5, by using the spectral band absorption filter 6 satisfying the above conditions, the light emission output can be reduced when the center wavelength (λ B) of the resonator output spectrum S1 is shifted to the high luminous efficiency side, and the light emission output can be increased when the center wavelength (λ B) is shifted to the low luminous efficiency side. Although the light emission intensity varies due to the change in film thickness by the adjustment operation as described above, the variation in luminance due to the change in film thickness is suppressed as shown by the calculation result in fig. 6. That is, while the variation of the film thickness of ± 1nm around the design value causes the variation of the luminance of ± 5% when the spectral band absorption filter 6 is not used, the variation of the luminance is suppressed to about ± 3% when the film thickness is varied by ± 1nm, although the luminance of the design value is reduced by about 10% when the spectral band absorption filter 6 is used. Note that the design value is a value optimized in luminance and chromaticity for light emission after passing through the filter.

Another example is shown in fig. 7. Fig. 7 shows the calculation results when the spectral band absorption filter 6 has an absorption characteristic of an approximate gaussian shape having an absorption center wavelength of 495nm and an absorption coefficient σ of 10 nm. The ratio Δ T [ ═ T (10)/T (0) ] of the transmittance was about 0.7. At this time, the spectral shape shows the same tendency as that of fig. 5, but since the value of the transmittance ratio Δ T becomes small, the fluctuation width of the light emission output due to the change in film thickness becomes large by that amount. As shown in the calculation results of fig. 8, although the luminance at the design value was reduced by 20%, when the film thickness was changed to ± 1nm, the luminance fluctuation due to the film thickness change was suppressed to about ± 1%. That is, by using the spectral band absorption filter 6 having a large transmittance change near the center wavelength of the resonator output spectrum S1, the luminance variation can be suppressed more favorably.

Another example is shown in fig. 9. Fig. 9 shows the calculation results when the spectral band absorption filter 6 has an absorption characteristic of an approximate gaussian shape having an absorption center wavelength of 495nm and an absorption coefficient σ of 15 nm. The ratio Δ T [ ═ T (10)/T (0) ] of the transmittance was about 0.6. At this time, the spectral shape tends to be similar to that of fig. 5 and 7, but since the value of the transmittance ratio Δ T becomes small, the range of variation in light emission output due to a change in film thickness becomes large. As shown in the calculation results of fig. 10, although the luminance at the design value was reduced by 35%, it was possible to maintain sufficient color purity and make the luminance variation by the film thickness variation almost zero. That is, by using the spectral band absorption filter 6 having a transmittance that changes more greatly in the vicinity of the center wavelength of the resonator output spectrum S1, it is possible to more reliably suppress the luminance variation.

FIG. 11 shows a calculation of the rate of change R of absorption of the spectral band absorption filter 6 at the center wavelength (λ B) of the resonator output spectrum S1_AThe result of the relationship with the rate of change in luminance RL (%) due to film thickness variation. Rate of change of absorption R_AIs obtained by dividing the slope of the absorption spectrum at the center wavelength (λ B) by the absorbance at the wavelength λ B, and calculating the formula R_A[1/nm]＝[dA(λB)/dλ]The value of/A (. lamda.B). The luminance change rate RL (%) is a change rate of luminance due to a film thickness deviation of d0 ± 2nm when the optimum film thickness satisfying NTSC color purity is d 0. Specifically, according to the luminance change rate RL [% ]](difference between maximum and minimum luminance values at d0 + -2 nm)]Luminance at/[ d0]X 100. As shown in the results of fig. 11, the absorption change rate R of the light-emitting element of blue (B) color_A[1/nm]Preferably-0.01 or less, more preferably-0.02 or less.

In the light-emitting element shown in fig. 1, the first and second reflecting members are constituted by the reflective electrode and the semi-transmissive electrode, but the present invention is not limited thereto, and a reflective film separate from the electrodes may be formed. At this time, the anode and the cathode on the element side of the reflective film may be transparent electrodes.

(second embodiment)

This embodiment is a modification of the first embodiment, and is an embodiment in which the color adjusted by the spectral band absorption filter 6 is red (R).

As shown in fig. 12, when red (R) is the target color, the center wavelength (λ B) of resonator output spectrum S1 is 620 ± 20 nm. It has a width of ± 20nm because the central wavelength (λ R) required for NTSC color purity depends on the width and PL shape of the resonator output spectrum S1. In addition, the offset width of the center wavelength (λ R) due to the film thickness unevenness is also considered. On the other hand, the center wavelength of the spectrum of the luminous efficacy function is 555nm under the photopic standard. In this case, in the preferred example of the present embodiment, the spectral band absorption filter 6 having the transmission spectrum S2 is used, and the absorption center wavelength (λ a) of the transmission spectrum S2 is, for example, 590 nm. More preferably, the peak absorption is 60% or more when the bottom absorption is 0%. Fig. 12 shows a light emission output spectrum S3 output by the transmission-band absorption filter 6 when the film thickness is set to the design value.

The absorption spectrum S2 of the spectral band absorption filter 6 is close to the resonator output spectrum S1, and the absorptance monotonically decreases toward the long wavelength side from the center wavelength (λ R) of the resonator output spectrum S1. Further, as an important factor, it is preferable that the change in transmittance in the vicinity of the center wavelength of the resonator output spectrum S1 is sufficiently suppressed to the extent that the luminance variation can be sufficiently suppressed. Specifically, as shown in fig. 13, when the transmittance at the center wavelength (λ R) is T (0) and the transmittance at a wavelength of-10 nm from the center wavelength is T (-10), the ratio Δ T [ ═ T (-10)/T (0) ] of the transmittances is preferably 0.9 or less, more preferably 0.7 or less, and still more preferably 0.6 or less.

Further, as in fig. 11, the absorption change rate R of the spectral band absorption filter 6 at the center wavelength (λ R) of the resonator output spectrum S1 was calculated_AThe result of the relationship with the rate of change in luminance RL (%) due to the change in film thickness wasAbsorption change rate R of red (R) light-emitting element_A[1/nm]Preferably +0.01 or more, more preferably +0.02 or more.

As described above, when the color of red (R) is the target color, the shape in the vicinity of the center wavelength (λ R) is controlled by the spectral band absorption filter 6 so that the light emission output decreases when the center wavelength (λ R) of the resonator output spectrum S1 shifts to the high luminous efficiency side and increases when the center wavelength (λ R) shifts to the low luminous efficiency side. Therefore, similarly to the case of blue (B), even when the film thickness varies within a range of ± 10nm of the design value, for example, and the optical path length of the resonator varies, the luminance variation can be suppressed.

(third embodiment)

The present embodiment is a modification of the first and second embodiments, and in the present embodiment, the target colors controlled by the spectral band absorption filter 6 are both blue (B) and red (R).

That is, the spectral band absorption filter having the absorption characteristics of the first embodiment and the spectral band absorption filter having the absorption characteristics of the second embodiment are prepared and stacked. Thus, the use of the filter not coated with the blue (B) and red (R) colors can provide an effect of suppressing the luminance variation. However, the present invention is not limited to the structure in which two layers are stacked, and filters may be disposed for the blue (B) and red (R) light emitting elements, respectively. With the above configuration, the luminance fluctuation of both blue (B) and red (R) can be suppressed.

The present embodiment is not limited to having two filters, and a single filter that absorbs two spectral bands may be used, for example, that satisfies both the absorption characteristic conditions of the first embodiment and the absorption characteristic conditions of the second embodiment.

(fourth embodiment)

In the first to third embodiments, examples of adjusting the optical path length of the RGB resonator by changing the thickness of the hole injection layer 31 are described. However, the optical path length of the RGB resonator may be adjusted by changing the thickness of the light-emitting layer 33 as shown in fig. 14.

(fifth embodiment)

In the first to fourth embodiments, the light-emitting element having the top emission structure is described as an example. However, the structure is not limited to this, and a bottom emission structure as shown in fig. 15 may be used. In the example shown in fig. 15, the reflective electrode 21 in fig. 1 is a semi-transmissive electrode, and the cathode 4 is a reflective electrode, thereby forming a bottom emission structure. In this case, as shown in fig. 15, the spectral band absorbing filter 6 may be disposed on the substrate 1, or the filter may be disposed so as to face the substrate 1 using the filter support substrate 7 shown in fig. 1. However, the structure is not limited thereto.

(sixth embodiment)

Next, an example of a process for manufacturing the RGB light-emitting element shown in fig. 1 will be described.

First, thin films of the reflective electrode 21 and the transparent electrode 22 are formed in this order by vapor deposition, sputtering, or the like. The electrodes 21, 22 may be patterned by photolithography. Then, a photosensitive resin containing fluorine is applied on the substrate 1, dried, and formed into a film, and then, for example, by photolithography, the partition wall portion 5 having a pattern as shown in fig. 1 is formed. In the case of the passive type, the electrodes 21 and 22 are formed in a stripe shape, and then the partition wall portion 5 is formed. On the other hand, in the case of the active type, the electrodes 21, 22 are formed in an island shape connected to each driving circuit, and then the partition wall portion 5 is formed.

Next, the liquid material of the hole injection layer 32 is applied to the regions partitioned by the partition wall portions 5 by, for example, an inkjet nozzle, and dried to form a film. The hole injection layer 32 and the light-emitting layer 33 are also formed by applying the respective elements by the same application method. The film thickness can be adjusted by adjusting, for example, the amount of liquid material applied. Next, the electron transport layer 34 and the cathode 4 are sequentially formed by a vapor deposition method. The cathode 4 may be patterned using a mask such as a metal mask or using the bank shape of the partition wall 5. For example, in the case of the passive type, the pattern of the cathode 4 may be formed in a stripe shape. On the other hand, in the case of the active type, it is possible to make it a plate electrode without forming a pattern.

Finally, the RGB light-emitting device shown in fig. 1 and 2 can be manufactured by attaching the spectral band absorbing filter 6 in the form of a thin film to the filter support substrate 7 and disposing the thin film support substrate 7 at a position facing the film formation surface from which light is emitted.

As described above, according to the first to sixth embodiments, in the light emitting element having the resonator structure, the wavelength corresponding to the minimum value of the transmission amount of the spectral band absorption filter is between the wavelength corresponding to the resonator structure resonator output spectrum having the maximum value and the wavelength corresponding to the light visual effect function having the maximum value, and part of the light emitted from the resonator structure is further absorbed by the spectral band absorption filter, whereby the luminance variation due to the variation in the optical path length of the resonator can be suppressed. In other words, even if the film thickness deviates from the design value, the allowable range of the film thickness unevenness becomes large because the luminance fluctuation is small, and the productivity can be improved and the cost can be reduced.

The technique described in the above embodiment mode can be applied to an inorganic thin-film light-emitting element (electroluminescence, light-emitting diode) having a layered 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 arranged in a matrix on the surface. The structure may be one in which light is transmitted from both the first and second reflecting members. Further, the present invention is not limited to RGB three colors, and may include one color, two colors, or other colors.

While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various substitutions, modifications and changes in form and details may be made therein without departing from the spirit of the invention and the scope of the appended claims. Therefore, the scope of the present invention is not limited to the above embodiments and drawings, but should be determined by the description of the claims and the equivalent embodiments.

Claims

1. A light-emitting element characterized in that:

having a resonator structure, an

A spectral band-absorbing filter for absorbing light in a spectral band,

wherein,

the resonator structure includes a first reflective member, a second reflective member, and a light-emitting layer disposed between the first reflective member and the second reflective member; light resonating between the first reflecting member and the second reflecting member is transmitted through the first reflecting member or the second reflecting member,

the spectral band absorbing filter transmits light transmitted through the first reflecting member or the second reflecting member,

the spectral band absorption filter has a transmission curve in which the transmittance decreases in the wavelength direction in which the optical visual effect function reaches a maximum value and increases after exceeding a wavelength at which the transmittance reaches a minimum value, and is located between a wavelength at which the resonator output spectrum of the resonator structure reaches a maximum value and a wavelength at which the optical visual effect function reaches a maximum value.

2. The light-emitting element according to claim 1, wherein:

the spectral band absorption filter exhibits a transmission curve in which the transmittance decreases with increasing wavelength and increases with increasing wavelength after exceeding a wavelength at which the transmittance reaches a minimum value.

3. The light-emitting element according to claim 1, wherein:

the spectral band absorption filter exhibits a transmission curve in which the transmittance decreases with decreasing wavelength and increases with decreasing wavelength after exceeding a wavelength at which the transmittance reaches a minimum value.

4. A display device having light emitting elements emitting red, green, and blue light, characterized in that:

at least the red and blue light-emitting elements have a resonator structure and a first spectral band absorbing filter,

wherein,

the resonator structures have a first reflective member, a second reflective member, and an organic layer, respectively; light resonating between the first reflecting member and the second reflecting member is transmitted through the first reflecting member or the second reflecting member,

the first spectral band absorbing filter absorbs light from the blue light-emitting element,

the first spectral band absorption filter exhibits a transmission curve in which the transmittance decreases with increasing wavelength and increases with increasing wavelength after exceeding a wavelength at which the transmittance reaches a minimum value, and is located between a wavelength at which the resonator output spectrum of the resonator structure reaches a maximum value and a wavelength at which the optical visual effect function reaches a maximum value.

5. A display device having light emitting elements emitting red, green, and blue light, characterized in that:

at least the red and blue light-emitting elements have a resonator structure and a second spectral band absorption filter,

wherein,

the second spectral band absorbing filter absorbs light from the red light-emitting element,

the second spectral band absorption filter is a transmission curve in which the transmittance decreases with decreasing wavelength and increases with decreasing wavelength after exceeding a wavelength at which the transmittance reaches a minimum value, and is located between a wavelength at which the resonator output spectrum of the resonator structure reaches a maximum value and a wavelength at which the optical visual effect function reaches a maximum value.