Organic electroluminescent color display having color transmitting layers and fluorescence converting layer with improved structure for color conversion efficiency on a color transmitting layer

An organic EL color display which can give off color light without recourse to a plurality of light emitting layers and be fabricated at low cost is built up of an organic EL color display comprising an organic EL light emitting device for emitting bluish green light, a blue transmitting layer, a green transmitting layer, a fluorescence converting layer that absorbs bluish green light and giving off light including red light, and a red transmitting layer.

BACKGROUND OF THE INVENTION 
The present invention relates to a display, and especially a color display, 
which comprises an organic electroluminescent light emitting device (which 
will hereinafter be often called an organic EL device for short) using an 
organic compound. 
In recent years, organic EL light emitting devices have been under 
intensive investigation. One typical light emitting device includes a 
glass substrate and a transparent electrode or anode of tin-doped indium 
oxide (ITO) or the like formed on the substrate. A thin film serving as a 
hole transporting layer is formed on the anode by evaporating a hole 
transporting material such as tetraphenyldiamine (TPD). A light emitting 
layer of a fluorescent material such as an aluminum quinolinol complex 
(Alq.sup.3) is deposited on the hole transporting layer. An electrode or 
cathode is formed thereon from a metal having a low work function such as 
magnesium. Such organic EL devices attract attentions because they can 
achieve a very high luminance ranging from 100 to 1,000 cd/m.sup.2 with a 
drive voltage of approximately 10 volts. 
Displays constructed using such an organic EL device may potentially have 
various applications, and its application to color displays in particular 
is an important subject. When a light emitting device is applied as a 
color display, for instance, it is a common procedure to vary the color of 
light emitted from the light emitting device or use color filters to 
obtain the three primary colors, blue, green and red. One known approach 
to varying the color of light emitted from a light emitting device itself 
is embodied by a color light emitting device comprising a cathode formed 
of an Ag.Mg thin film and an anode formed of ITO as typically set forth in 
SID 96 DIGEST.185 14.2: Novel Transparent Organic Electro-luminescent 
Devices G. Gu, V. BBulovic, P. E. Burrows, S. RForrest, M. E. Tompson. 
However, this color light emitting device (heterostructure organic light 
emitting device) has a multilayer structure comprising light emitting 
layers (Red ETL, Green ETL and Blue ETL) corresponding to the three 
primary colors, R, G and B, respectively. One problem with this device is 
that its structure becomes complicated with a production cost increase 
because a cathode and an anode must be provided for each light emitting 
layer. Another problem is that the color balance is disturbed with time 
due to a service life difference between the three primary colors. 
Even with a color display constructed using a single light emitting device 
in combination with color filters, on the other hand, it is difficult to 
achieve the emission of white light because an organic EL device has a 
limited light emission wavelength range with the uneven distribution of 
its center wavelength. The sole use of color filters leads to a deficiency 
of light sources for some wavelengths. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an inexpensive organic EL 
color display which can give off colors without recourse to a plurality of 
light emitting layers. 
Such an object is accomplished by the inventions defined below as (1) to 
(4). 
(1) An organic EL color display comprising an organic EL light emitting 
device for emitting bluish green light, a blue transmitting layer, a green 
transmitting layer, a fluorescence converting layer that absorbs bluish 
green light and emits light including red light, and a red transmitting 
layer. 
(2) The organic EL color display of (1), wherein said organic EL light 
emitting device is formed at least in such a way as to enclose said 
fluorescence converting layer, and a cathode of said EL light emitting 
device is extended down along sides of said fluorescence converting layer. 
(3) The organic EL color display of (2), wherein at least said fluorescence 
converting layer is tapered on sides thereof in such a way that an area of 
said fluorescence converting layer diminishes toward said organic EL light 
emitting device. 
(4) The organic EL color display of (1), wherein said organic EL light 
emitting device is formed at least in such a way as to enclose said 
fluorescence converting layer, and a surface of said fluorescence 
converting layer opposite to said organic EL light emitting device is 
convex toward said organic EL light emitting device.

DETAILED EXPLANATION OF THE INVENTION 
Some preferred embodiments of the present invention will now be explained 
more specifically. 
The organic EL color display of the invention comprises an organic EL light 
emitting device for emitting bluish green light, a blue transmitting 
layer, a green transmitting layer, a fluorescence converting layer for 
absorbing bluish green light and emitting orange light, and a red 
transmitting layer. 
For the organic EL light emitting device for emitting bluish green light, 
it is preferable to use a device having a light emission maximum 
wavelength .lambda.max of 400 to 550 nm, especially about 460 to 500 nm. 
The half-width of a light emission peak is in the range of 50 to 150 nm, 
preferably 80 to 150 nm. In the practice of the invention, there may be 
two or more light emission peaks. 
For the blue, green, and red transmitting layers of the invention, it is 
preferable to use color filters. For the color filters, use may be made of 
those used on liquid crystal displays, etc. However, it is preferable to 
control the characteristics of color filters in conformity to light 
emitted by the organic EL device, so that the efficiency of color 
selection, and color purity can be optimized. It is also preferable to use 
color filters capable of cutting off light of short wavelengths absorbed 
by an EL device material or the fluorescence converting layer, thereby 
improving the light resistance of the device and the contrast of displays 
presented. The light cut off in this case is light having wavelength of at 
least 560 nm and light having wavelength of up to 480 nm for green, light 
having wavelength of at least 490 nm for blue, and light having wavelength 
of up to 580 nm for red. By use of such color filters, it is preferable to 
regulate the respective layers in conformity to chromaticity coordinates 
according to the NTSC standard or the current CRT standard. Such 
chromaticity coordinates may be determined by use of general chromaticity 
coordinates measuring equipment, for instance, BM-7 or SR-1 made by Topcon 
Co., Ltd. Each color filter may have a thickness of about 0.5 to 20 .mu.m. 
Alternatively, it is acceptable to use optical thin films such as a 
dielectric multilayer films in place of the color filters. 
The fluorescence converting layer of the invention is provided to absorb 
light emitted from the EL device and allow a phosphor in the fluorescence 
converting film to give off light for the color conversion of color 
emission. To this end the layer is formed of a binder, fluorescent 
material or light absorbing material. 
The fluorescent material used herein should basically have high 
fluorescence quantum efficiency, and preferably exhibit strong absorption 
in the EL light emission wavelength range. Specifically, it is preferable 
to use a fluorescent material in which the light emission maximum 
wavelength .lambda.max of a fluorescent spectrum is in the range of 580 to 
630 nm and the half-width of a light emission peak is anyway in the range 
of 10 to 100 nm. The fluorescent material suitable for the practice of the 
invention is dyes for lasers, for instance, Rhodamine base compounds, 
perylene base compounds, cyanine base compounds, phthalocyanine base 
compounds (including subphthalocyanine, etc.), naphthaloimide base 
compounds, condensed cyclic hydrocarbon base compounds, condensed 
heterocyclic compounds, and styryl base compounds. 
Basically, the binder may be selected from materials that do not extinguish 
fluorescence. Preference is given to materials that can be finely 
patterned by means of lithography, printing or the like, and that are not 
damaged upon ITO film formation. 
The light absorbing material is used when the absorption of light by the 
fluorescent material is insufficient, and may be dispensed with if 
unnecessary. The light absorbing material is preferably selected from 
materials that do not extinguish the fluorescence the fluorescent material 
gives off. 
By use of such a fluorescence converting filter, it is possible to obtain 
preferable values for x and y on the CIE chromaticity coordinates. The 
fluorescence converting filter has preferably a thickness of about 0.5 to 
50 .mu.m. 
One general embodiment of the organic EL display according to the invention 
is shown in FIG. 1. In the organic EL display embodiment depicted in FIG. 
1, a green, and blue light emitting portion G, and B comprises a glass 
substrate 1, a color filter 2g, and 2b, and an organic EL light emitting 
device 3 in the described order, and a red light emitting portion R 
comprises a glass substrate 1, a color filter 2r, a fluorescence 
converting filter 4, and an organic EL light emitting device 3 in the 
described order. 
Thus, the green, and blue light emitting portion is obtainable by using the 
organic EL light emitting device 3 for emitting bluish green light in 
combination with the green, and blue transmitting layer 2g, and 2b, and 
the red light emitting portion is obtainable by using the organic EL light 
emitting device 3 for emitting bluish green light in combination with the 
fluorescence converting filter 4 that converts the bluish green light 
emitted from the organic EL light emitting device to a wavelength close to 
red and the red transmitting layer 2r. In other words, a color display can 
be composed only of a light emitting layer for giving off monochromatic 
light by allowing the fluorescence converting filter to make up for light 
of wavelength in the red direction, of which the bluish green light is 
devoid. 
One embodiment of the organic EL light emitting device according to the 
invention is shown in FIG. 2. The organic EL light emitting device 
depicted in FIG. 2 comprises, in order from a blue, green, and red 
transmitting layer or a fluorescence converting filter (not shown), an 
anode 22 serving as a transparent electrode, a hole injecting layer 23, a 
hole transporting layer 24, a light emitting layer 25, an electron 
injecting and transporting layer 26, and a cathode 27. 
The EL device of the invention is never limited to the illustrated 
embodiment, and so may have various structures. For instance, the electron 
injecting and transporting layer may be dispensed with or made integral 
with the light emitting layer, or alternatively the hole injecting, and 
transporting layers may be formed as one integral piece or as a combined 
hole injecting and transporting layer. 
The cathode may be formed by evaporation or sputtering. Such organic layers 
as represented by the light emitting layer may be formed by vacuum 
evaporation or the like, and the anode may be constructed as mentioned 
above. If necessary, these layers may be patterned, for example, by mask 
evaporation or film formation followed by etching whereby a desired light 
emitting pattern is accomplished. If the substrate bears a thin film 
transistor (TFT), the respective layers may be formed in accordance with 
the pattern of TFT to accomplish a display or drive pattern immediately. 
Finally, a protective layer is formed over the device using inorganic 
materials such as SiOx and organic materials such as Teflon. 
One specific embodiment of the organic EL display according to the 
invention is illustrated in FIG. 3. In this embodiment, in order from a 
substrate 21, a color filter 2r and a fluorescence converting filter 4 are 
disposed thereon. Furthermore, an anode 22, a light blocking layer 29, an 
organic EL light emitting device 3a and a cathode 27 are stacked on the 
filter 4 in the described order. It is here noted that the light blocking 
layer 29 is provided to block out light coming from organic EL light 
emitting device 3a, thereby preventing direct leakage of the light onto 
glass substrate 21. The light emitted from organic EL light emitting 
device 3a is accordingly incident on a portion of fluorescent filter 4 
that is unblocked by light blocking layer 29. At this time, the light 
emitted from organic EL light emitting device 3a is radiated in every 
direction, with a part of the light being reflected by cathode 27. 
Likewise, the aforesaid emitted light and the fluorescence converted by 
fluorescence converting filter 4 are radiated in every direction. While 
the light propagating toward glass substrate 21 is immediately released 
out of glass substrate 21, the inversely propagating light is reflected by 
cathode 27 and released from within glass substrate 21. For this reason, 
the optical path taken by light in fluorescence converting filter 4 
becomes so long that the efficiency of conversion can be improved. In 
addition, it is possible to make effective use of light substantially lost 
so far in the prior art, resulting in improvements in the efficiency of 
light emission (luminance). 
Another specific embodiment of the organic EL display according to the 
invention is illustrated in FIG. 4. In this display embodiment, a color 
filter 2r and a fluorescence converting filter 4 are so tapered on their 
sides that the sizes of color filter 2r and converting filter 4 diminish 
successively from the side of a glass substrate 21 toward a cathode 27. In 
such an arrangement, light propagating from the sides of color filter 2r 
and fluorescence converting filter 4 toward the cathode takes the form of 
reflected light having an angle with respect to glass substrate 21 that is 
closer to verticality than would be possible in the embodiment of FIG. 3. 
It is thus possible to reduce light that is closer to parallelism rather 
than at a certain angle with respect to glass substrate 21 and so is 
hardly released out of the substrate, and extend the optical path taken by 
light in fluorescence converting filter 4, resulting in improvements in 
the efficiency of conversion. It is further possible to make effective use 
of light substantially lost so far in the prior art, resulting in 
improvements in the efficiency of light emission (luminance). While, in 
this embodiment, the sides of color filter 2r and fluorescence converting 
filter 4 are tapered, it is understood that only the sides of fluorescence 
converting filter 4 may be tapered. This second embodiment of the 
invention is otherwise similar to the embodiment of FIG. 3, and for 
simplification of explanation like parts or elements are indicated by like 
numerals. 
Yet another specific embodiment of the organic EL display of the invention 
is illustrated in FIG. 5. In this display embodiment, the side of a 
fluorescence converting filter 4 opposite to a cathode 27 is formed into a 
curved shape, and preferably in such a shape that it can function as a 
sort of lens. In this lens arrangement, light propagating from 
fluorescence converting filter 4 toward the cathode takes the form of 
reflected light having an angle with respect to glass substrate 21 that is 
closer to verticality than would be possible in the embodiment of FIG. 3. 
It is thus possible to reduce light that is closer to parallelism rather 
than at a certain angle with respect to glass substrate 21 and so is 
hardly released out of the substrate, and extend the optical path taken by 
light in fluorescence converting filter 4, resulting in improvements in 
the efficiency of conversion. It is further possible to make effective use 
of light substantially lost so far in the prior art, resulting in 
improvements in the efficiency of light emission (luminance). This third 
embodiment of the invention is otherwise similar to the embodiment of FIG. 
3, and for simplification of explanation like parts or elements are 
indicated by like numerals. 
To achieve effective electron injection, the cathode is preferably made up 
of a material having a low work function, for instance, any one of metal 
elements such as K, Li, Na, Mg, La, Ce, Ca, Sr, Ba, Al, Ag, In, Sn, Zn, 
and Zr. To improve the stability of the cathode, it is preferably made up 
of a binary or ternary alloy system comprising two or three of the 
aforesaid metal elements. Preferable for such an alloy system, for 
instance, are Ag.Mg (Ag: 1 to 20 at %), Al.Li (Li: 0.1 to 20 at %), In.Mg 
(Mg: 50 to 80 at %), and Al.Ca (Ca: 5 to 20 at %). 
The cathode thin film may have at least a thickness large enough to achieve 
satisfactory electron injection, for instance, of at least 50 nm, and 
preferably at least 100 nm. While there is no upper limit to film 
thickness, a film thickness of about 100 to 500 nm is usually preferred. 
The protective layer may be either transparent or opaque. To make the 
protective layer transparent, it is preferable to make a selection from 
transparent materials (e.g., SiO.sub.2, and SIALON), or alternatively 
perform thickness control (in such a manner that at least 80% of emitted 
light can transmit through the protective layer). In general, the 
protective layer may have a thickness of about50 to 1,200 nm. Although no 
particular limitation is placed on how to form the protective layer, that 
is, the protective layer may be formed as by evaporation, it is preferable 
to make use of sputtering which enables the protective layer to be formed 
subsequently to the formation of the cathode. 
Here the organic layer provided in the EL device of the invention is 
explained. 
The light emitting layer has functions of injecting holes and electrons, 
transporting them, and recombining holes and electrons to create excitons. 
For the light emitting layer, it is preferable to use a compound that is 
stable to both electron and hole carriers, and is of strong fluorescence 
intensity. 
The hole injecting layer, which is sometimes referred to as an electron 
injecting layer, has a function of facilitating injection of holes from 
the anode, and the hole transporting layer, which is often called an 
electron transporting layer, has functions of transporting holes, and 
blocking electron transportation. 
For example, when the compound used in the light emitting layer has a 
relatively low electron injecting and transporting function, an electron 
injecting and transporting layer having functions of facilitating 
injection of electrons from the cathode, transporting electrons, and 
blocking hole transportation may be provided between the light emitting 
layer and the cathode. 
The hole injecting layer, hole transporting layer, and electron injecting 
and transporting layer are effective for increasing the number of holes 
and electrons injected into the light emitting layer and confining holes 
and electrons therein for optimizing the recombination region to improve 
light emission efficiency. 
The electron injecting and transporting layer may be constructed in the 
form of a double-layered structure consisting separately of a layer having 
an injecting function and a layer having a transporting function. 
The thickness of the light emitting layer, the total thickness of the hole 
injecting and transporting layers, and the thickness of the electron 
injecting and transporting layer are not critical to the practice of the 
present invention, and so vary with their particular formation techniques. 
However, a thickness of about 5 to 100 nm is usually preferable. 
The thickness of the hole injecting and transporting layers, and the 
electron injecting and transporting layer is equal to, or ranges from 
about 1/10 times to about 10 times, the thickness of the light emitting 
layer although it depends on the design of the recombination/light 
emitting region. When the electron or hole injecting and transporting 
layer is separated into an injecting layer and a transporting layer, it is 
preferable that the injecting layer is at least 1 nm thick and the 
transporting layer is at least 20 nm thick. The upper limit to thickness 
is usually about 100 nm for the injecting layer and about 100 nm for the 
transporting layer. The same film thickness applies when two injecting and 
transporting layers are provided. 
By controlling the layer thickness while taking into account the carrier 
mobility and carrier density (depending on ionization potential and 
electron affinity) of the light emitting layer, the electron injecting and 
transporting layer, and the hole injecting and transporting layer to be 
combined, the free design of the recombination/light emitting region, the 
design of emission color, the control of the luminance and spectrum of 
light emission by the interference of both the electrodes, and the control 
of the spatial distribution of light emission become feasible. 
In the organic EL device according to the invention, the light emitting 
layer contains a bluish green fluorescent material that is a compound 
capable of emitting light. The fluorescent material used herein, for 
instance, may be selected from bluish green light emitting materials such 
as those disclosed in JP-A's 6-110569 (phenylanthracene derivatives), 
6-114456 (tetraarylethene derivatives), 6-100857 and 2-247278. 
Additionally, quinacridone, coumarin, rubrene, and styryl dyes, 
tetraphenylbutadiene, anthracene, perylene, coronene, and 
12-phthaloperinone derivatives may be used alone or in admixture with the 
fluorescent material. In the practice of the invention, a selection may be 
made from the aforesaid materials emitting bluish green light. The light 
emitting layer may also serve as an electron injecting and transporting 
layer. These fluorescent materials may be evaporated or otherwise 
deposited. 
For the electron injecting and transporting layer which is provided if 
necessary, there may be used organic metal complexes such as 
tris(8-quinolinolato)aluminum, oxadiazole derivatives, perylene 
derivatives, pyridine derivatives, pyrimidine derivatives, quinoline 
derivatives, quinoxaline derivative, diphenylquinone derivatives, and 
nitro-substituted fluorene derivatives. The electron injecting and 
transporting layer may also serve as a light emitting layer as previously 
mentioned. Like the light emitting layer, the electron injecting and 
transporting layer may be formed by evaporation or the like. 
Where the electron injecting and transporting layer is a double-layered 
structure comprising an electron injecting layer and an electron 
transporting layer, two or more compounds are selected in a proper 
combination from the compounds commonly used for electron injecting and 
transporting layers. In this regard, it is preferred to laminate layers in 
such an order that a compound layer having a greater electron affinity is 
disposed contiguous to the cathode. This order of lamination also applies 
where a plurality of electron injecting and transporting layers are 
provided. 
For the hole injecting and transporting layers, use may be made of various 
organic compounds as disclosed in JP-A's 63-295695, 2-191694, 3-792, 
5-234681, 5-239455, 5-299174, 7-126225, 7-126226 and 8-100172 and EP 
0650955A1. Examples are tetraarylbenzidine compounds (tetraaryldiamine or 
tetraphenyldiamine (TPD)), aromatic tertiary amines, hydrazone 
derivatives, carbozole derivatives, triazole derivatives, imidazole 
derivatives, oxadiazole derivatives having an amino group, and 
polythiophenes. Where these compounds are used in combination of two or 
more, they may be stacked as separate layers, or otherwise mixed. 
For the hole injecting and transporting layers, two or more compounds are 
selected in a proper combination from the compounds mentioned above. In 
this regard, it is preferred to laminate layers in such an order that a 
compound layer having a lower ionization potential is disposed contiguous 
to the anode (ITO, etc.). It is also preferred to use a compound having 
good thin film forming ability at the anode surface. This order of 
lamination holds for the provision of two or more hole injecting and 
transporting layers, and is effective as well for lowering drive voltage 
and preventing the occurrence of current leakage and the appearance and 
growth of dark spots. Since evaporation is utilized in the manufacture of 
devices, films as thin as about 1 to 10 nm can be formed in a uniform and 
pinhole-free state, which restrains any change in color tone of light 
emission and a drop of efficiency by re-absorption even if a compound 
having a low ionization potential and absorption in the visible range is 
used in the hole injecting layer. 
Like the light emitting layer and so on, the hole injecting and 
transporting layers may be formed by evaporating the aforesaid compounds. 
For the transparent electrode used as the anode in the practice of the 
invention, the type and thickness of an anode-forming material are 
preferably determined such that at least 80% of emitted light transmits 
therethrough. For example, tin-doped indium oxide (ITO), zinc-doped indium 
oxide (IZO), SnO.sub.2, and polypyrrole doped with a dopant may be used as 
the anode. The anode has preferably a thickness of about 10 to 500 nm. The 
drive voltage should preferably be low enough to improve the reliability 
of the device. 
For the substrate material, transparent or translucent materials such as 
glass, quartz and resins are used when emitted light is taken out of the 
substrate side. The substrate may be provided with a color filter film, 
fluorescent material-containing color conversion film or dielectric 
reflecting film for controlling the color of light emission. 
The organic EL light emitting device of the invention is generally of the 
DC drive type while it may be of the AC or pulse drive type. The applied 
voltage is generally about 5 to 20 volts. 
EXAMPLE 
The present invention are explained more specifically with reference to 
some examples. 
Example 1 
Preparation of Organic El Device 
An ITO transparent anode was formed at a thickness of 100 nm on a glass 
substrate at a rate of 10 nm/min., following by patterning. 
The target used was In.sub.2 O.sub.3 having SnO.sub.2 (10 mol %) 
incorporated therein, the sputtering gas used was Ar, and the gas pressure 
applied was 1 Pa. The temperature and power applied were 80.degree. C. and 
1 W/cm.sup.2, respectively, with a spacing of 8 cm between the substrate 
and the target. 
The anode was ultrasonically washed with neutral detergent, acetone, and 
ethanol, and then pulled up from boiling ethanol, followed by drying. The 
semi-transparent anode was cleaned on its surface with UV/O.sub.3. 
Subsequently, the anode was fixed to a substrate holder in a vacuum 
evaporation apparatus, which was evacuated to a vacuum of 
1.times.10.sup.-4 Pa or lower. 
With the vacuum kept, MTDATA having the following formula I was evaporated 
on the anode at a deposition rate of 0.2 nm/sec. to a thickness of 50 nm 
to form a hole injecting layer. 
##STR1## 
With the vacuum still kept, 
N,N,N',N'-tetra-m-biphenyl-tolyl-4,4'-diamino-1,1'-biphenyl (TPD) having 
the following formula II was evaporated at a deposition rate of 0.2 
nm/sec. to a thickness of 20 nm to form a hole transporting layer. 
##STR2## 
With the vacuum still kept, DPA having the following formula III was 
evaporated at a deposition rate of 0.2 nm/sec. to a thickness of 20 nm to 
form a light emitting layer. 
##STR3## 
With the vacuum still kept, DQX having the following formula IV was 
evaporated at a deposition rate of 0.2 nm/sec. to a thickness of 20 nm to 
form an electron injecting and transporting layer. 
##STR4## 
Then, the anode was transferred from the vacuum evaporation apparatus to a 
sputtering apparatus wherein an Ag.Mg target was used to form a cathode at 
a rate of 10 nm/min. to a thickness of 230 nm by means of DC sputtering. 
The sputtering gas, gas pressure, and power applied were Ar, 1 Pa, and 100 
W, respectively, with a spacing of 8 cm between the substrate and the 
target. 
Finally, aluminum was sputtered to a thickness of 200 nm to form a 
protective layer, thereby obtaining an organic thin film light emitting 
device (organic EL device). 
A DC voltage was applied across the organic thin film light emitting device 
to continuously drive the device at a constant current density of 10 
mA/cm.sup.2. At the initial, the device when driven at 8.5 volts was found 
to emit green light at a luminance of 450 cd/m.sup.2 (light emission 
maximum wavelength .lambda.max=460 nm). This organic EL device was found 
to have such relation between light emission luminance and light emission 
wavelength as plotted in FIG. 6. 
Preparation of Organic EL Display 
A color display having such structure as shown in FIG. 1 was prepared using 
the aforesaid organic EL device as a device, employing as blue, green, and 
red transmitting layers color filters made by Fuji Hanto Co., Ltd., one 
cutting off light having wavelength of at least 560 nm and light having 
wavelength of up to 480 nm for green, one cutting off light having 
wavelength of at least 90 nm for blue, and one cutting off light having 
wavelength of up to 580 nm for red, and utilizing as a fluorescence 
converting layer a mixture of Rumogen made by BASF and CT-1 made by Fuji 
Hanto Co., Ltd. in which the light emission maximum wavelength .lambda.max 
of a fluorescence spectrum was 610 nm and the half-width of a light 
emission peak was 70 nm. 
The organic EL light emitting device of the thus fabricated display was 
driven as mentioned above. Consequently, the blue light emitting portion 
gave off blue light at a luminance of 171 cd/m.sup.2 with chromaticity 
coordinates of x=0.129 and y=0.105, the green light emitting portion gave 
off green light at a luminance of 310 cd/m.sup.2 with chromaticity 
coordinates of x=0.340 and y=0.625, and the red light emitting portion 
gave off red light at a luminance of 75 cd/m.sup.2 with chromaticity 
coordinates of x=0.649 and y=0.338. 
Example 2 
An organic EL display was constructed as in Example 1 with the exception 
that an organic El light emitting device was extended down along the sides 
of color, and fluorescent filters in such a way as to have such structure 
as shown in FIG. 3. The red light emitting portion was found to have a 
light emission luminance of 100 cd/m.sup.2 improved over that obtained in 
Example 1. 
Example 3 
Following Example 1, color, and fluorescent filters were formed in such a 
way as to have such structure as shown in FIG. 4. In this case, the sides 
of the color, and fluorescent filters made an angle of 15.degree. with a 
plane vertical to a glass substrate. An organic EL light emitting device 
was extended down along the sides of the color, and fluorescent filters. 
Then, an organic EL display was constructed under otherwise similar 
conditions as in Example 1. Consequently, the red light emitting portion 
was found to have a light emission luminance of 110 cd/m.sup.2 much higher 
than that obtained in Example 1. 
Example 4 
An organic EL display was constructed following Example 1 with the 
exception that a fluorescent filter was constructed in a lens form and an 
organic EL light emitting device was extended from this lens surface to a 
color filter in such a way as to have such structure as shown in FIG. 5. 
As a result, the red light emitting portion was found to have a light 
emission luminance of 110 cd/m.sup.2 much higher than that obtained in 
Example 1. 
According to the present invention, an inexpensive yet greatly efficient 
organic EL color display capable of giving off color light can be provided 
without recourse to a plurality of light emitting layers. 
Although some preferred embodiments have been described, many modifications 
and variations may be made thereto in the light of the above teachings. It 
is therefore to be understood that within the scope of the appended 
claims, the invention may be practiced otherwise than as specifically 
described.