JP6296239B2 - Light emitting electrochemical element and light emitting device having the light emitting electrochemical element - Google Patents

Description

  The present invention relates to a light-emitting electrochemical element and a light-emitting device having the light-emitting electrochemical element.

2. Description of the Related Art In recent years, an organic electroluminescent element (hereinafter also referred to as OLED: Organic Light-Emitting Diode) can generally form a light-emitting surface that is light and thin and has a large area. The use to is expected.
This organic electroluminescent element is generally composed of an anode, a cathode, and a light emitting layer, and by applying a voltage between both electrodes, holes injected from the anode and electrons injected from the cathode are combined in the light emitting layer. It emits light. In order to increase the luminous efficiency of the organic electroluminescent device, it is necessary to provide a hole injection layer or an electron injection layer for improving the recombination efficiency of holes and electrons in addition to the light emitting layer to form a multilayer structure. There is a problem that the structure becomes complicated and the manufacturing process becomes complicated. In addition, a high electric field is required for driving.

As an element for solving the problems of the organic electroluminescence element described above, a light-emitting electrochemical element [hereinafter sometimes abbreviated as LEC (Light-emitting Electrochemical Cell)] is disclosed in, for example, Patent Document 1, Patent Document 2, and the like. Proposed.
The LEC includes a first electrode, a second electrode, and a light emitting layer provided between the electrodes. The light-emitting layer is formed by dispersing a conductive polymer serving as a light-emitting material and a supporting salt in an electrolyte. In this LEC, by applying a voltage between the two electrodes, a pn junction or a pin junction is formed by injection of positive and negative charges from the electrode and movement of both positive and negative ions of the supporting salt. It is estimated that light is emitted by recombination of electrons.
This LEC generally has (1) low driving voltage, (2) use of unstable electrodes in the atmosphere, and (3) device fabrication with a single light-emitting layer compared to OLEDs. Therefore, it has advantages such as simple element configuration. Among them, LEC using a solid electrolyte is particularly attracting attention because it is easy to seal at the time of device manufacture and has little influence on the environment when the device is damaged.

JP 2008-291230 A Special table 2012-516033 gazette

  However, when such an LEC is applied to uses such as lighting and a display, it is necessary to emit white light. Conventional LEC development is directed to improving the performance of monochromatic light emitting elements such as blue (B), green (G), and red (R), as shown in Patent Documents 1 and 2 above. White light emission by LEC is an undeveloped area. In order to obtain LEC that emits white light, for example, it is conceivable that the light emitting layer has a three-layer structure composed of red, green, and blue, or a filter is provided for color conversion. However, in terms of performance, cost, and manufacturing method, A satisfactory white light emitting LEC has not yet been obtained.

  Accordingly, an object of the present invention is to provide a light emitting electrochemical element capable of obtaining white light emission almost as white as possible while having an element structure having a simple structure of a single layer, and a light emitting device having the light emitting electrochemical element. It is in.

  As a result of intensive studies on the above problems, the present inventors have found that in the LEC in which the first electrode, the light emitting layer, and the second electrode are laminated in this order, the light emitting layer comprises a conductive polymer, an electrolyte, a supporting salt, and a nitrogen-containing conjugate. LEC containing a compound based on the above has been developed and the present invention has been completed. Specifically, by applying a voltage between the first electrode and the second electrode, the blue light emission from the conductive polymer is formed from between the conductive polymer and the nitrogen-containing conjugated compound. The present inventors have found that the exciplex fluorescence generated by the above is emitted, and that both the light emission emits excellent white light with high luminance at a low driving voltage.

That is, according to the present invention, in the light emitting electrochemical device in which the first electrode, the light emitting layer, and the second electrode are laminated in this order, the light emitting layer comprises a conductive polymer, an electrolyte, a supporting salt, and a nitrogen-containing conjugated system. When the compound contains a compound and a voltage is applied between the first electrode and the second electrode, the conductive polymer emits blue light, and an excitement is generated between the conductive polymer and the nitrogen-containing conjugated compound. A light emitting electrochemical device is provided in which a plex is formed to emit exciplex fluorescence.
In addition, a light-emitting device that has the light-emitting electrochemical element and a voltage unit that applies a voltage and emits white light is provided.

The light-emitting electrochemical element of the present invention can have a single light-emitting layer, and has a simple structure, yet emits white light with high brightness and almost white light at a low driving voltage. can get. In the present application, white as close as possible to white means that x and y are in the range of 0.33 ± 0.09 in the chromaticity diagram. The emission color of the light-emitting electrochemical element of the present invention and the compound related to the element is applied to the CIE chromaticity coordinates based on the result of measurement using “instant multi-photometry system (wide dynamic range type) MCPD9800” (manufactured by Otsuka Electronics Co., Ltd.). The color when In addition, hereinafter, a thing with such a favorable whiteness may be called high whiteness.
Further, by using a light emitting device using the light emitting electrochemical element of the present invention, a light emitting device capable of obtaining white light with high brightness and high whiteness can be obtained.

It is a schematic sectional drawing of the light emitting electrochemical element of this invention. It is a figure of the luminance-voltage (LV) characteristic of each element of an Example and a comparative example. It is an EL (Electro-luminescence) spectrum figure of each element of an example and a comparative example. It is PL (Photo-luminescence) spectrum figure of each element of an Example and a comparative example. It is a chromaticity diagram of each element of an Example and a comparative example.

Hereinafter, the present invention will be described in detail.
The light emitting electrochemical device of the present invention has a laminated structure in which a first electrode, a light emitting layer, and a second electrode are laminated in this order. The light-emitting layer contains a conductive polymer, an electrolyte, a supporting salt, and a nitrogen-containing conjugated compound, and the conductive polymer is blue by applying a voltage between the first electrode and the second electrode. In addition to light emission, an exciplex is formed between the conductive polymer and the nitrogen-containing conjugated compound to emit exciplex fluorescence, and white light is emitted by the plurality of light emission.
Here, an exciplex is a dimer composed of different types of atoms or molecules, and is formed by bonding an excited state atom or molecule with another type of ground state atom or molecule. Exciplex fluorescence is fluorescence emitted from an excited exciplex.

Examples of the electrolyte contained in the light emitting layer include a polymer electrolyte and an inorganic electrolyte. Among these, a polymer is preferable. As this polymer, each of the skeleton units is — (C—C—O) _n —, — (C—C (CH ₃ ) —O) _n —, — (C—C—N) _n —, or — (C Examples thereof include polyethylene oxide, polypropylene oxide, polyethyleneimine, polyethylene sulfide, or a resin having a branched structure as a structure having these in the main chain or side chain, represented by —C—S) _n —. Further, for example, in these skeleton units such as polyethylene oxide, the hydrogen atom to be bonded may be substituted with an alkyl group such as methyl or ethyl, or an aryl group such as phenyl group. Furthermore, resins such as polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, polycarbonate, and polyacrylonitrile can also be suitably used as the electrolyte polymer of this embodiment.
Among these, polyalkylene oxide is preferable, and polyethylene oxide is more preferable. This is because it is excellent in terms of workability, ionic conductivity, mechanical properties, and transparency.

The light emitting layer contains a supporting salt in addition to the electrolyte. Examples of the supporting salt include ionic liquids, lithium salts such as LiCl, LiBr, LiI, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiCF ₃ SO ₃ , potassium, and the like. Salts such as KCl, KI, KBr, KCF ₃ SO ₃ and the like, sodium salts such as NaCl, NaI, NaBr, or tetraalkylammonium salts such as tetraethylammonium perfluoride, tetraethylammonium perchlorate, tetrafluoroborate Examples thereof include butylammonium, tetrabutylammonium perchlorate, and tetrabutylammonium halide. The alkyl chain lengths of the quaternary ammonium salts described above may be the same or different, and only one kind may be used as necessary, or two or more kinds may be used in combination. Among these, KCF ₃ SO ₃ is preferable, and excellent in terms of ionic conductivity, compatibility, and stability.
The ionic liquid of the present invention means a salt that exists as a liquid at room temperature (25 ° C.).

  Examples of the cation of the ionic liquid include an imidazolium cation, a pyridinium cation, a pyrrolidinium cation, a piperidinium cation, a tetraalkylammonium cation, a pyrazolium cation, and a tetraalkylphosphonium cation.

  Examples of the imidazolium cation include 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-allyl-3-methylimidazolium, 1 -Allyl-3-ethylimidazolium, 1-allyl-3-butylimidazolium, 1,3-diallylimidazolium and the like.

  Examples of the pyridinium cation include 1-propylpyridinium, 1-butylpyridinium, 1-ethyl-3- (hydroxymethyl) pyridinium, 1-ethyl-3-methylpyridinium, and the like.

  Examples of the pyrrolidinium cation include N-methyl-N-propylpyrrolidinium, N-methyl-N-butylpyrrolidinium, N-methyl-N-methoxymethylpyrrolidinium, and the like.

  Examples of the piperidinium cation include N-methyl-N-propylpiperidinium.

  Examples of the tetraalkylammonium cation include N, N, N-trimethyl-N-propylammonium and methyltrioctylammonium.

  Examples of the pyrazolium cation include 1-ethyl-2,3,5-trimethylpyrazolium, 1-propyl-2,3,5-trimethylpyrazolium, 1-butyl-2,3,5- And trimethylpyrazolium.

In addition, examples of the anion that forms an ionic liquid in combination with the above cation include, for example, BF ₄ ⁻ , NO ₃ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , CH ₃ CH ₂ OSO ₃ ⁻ , CH ₃ CO ₂ ⁻ , or ^{_{, CF 3 CO 2 -, CF}} 3 SO 3 -, (CF 3 SO 2) 2 N - [ bis (trifluoromethylsulfonyl) _{imide], (CF 3 SO 2)} 3 C - fluoroalkyl group-containing anions such as Can be mentioned.

  The light emitting layer contains a conductive polymer as a light emitting compound. The conductive polymer emits light by itself and forms an exciplex with the nitrogen-containing conjugated compound to emit exciplex fluorescence. The conductive polymer of the present invention has an electron and / or hole transport function, and is a polymer that can efficiently transport electrons and / or holes. Among these, a polymer or copolymer having a fluorene skeleton is preferable in that it excites good exciplex fluorescence in combination with a nitrogen-containing conjugated compound. A polymer or copolymer having a fluorene skeleton emits blue light by itself and can form an exciplex to emit exciplex fluorescence.

As the polymer having a fluorene skeleton, a polymer represented by the following formula (1) is preferable. This is because white light with high whiteness can be obtained.
[In Formula (1), R is a C1-C20 alkyl group, m shows a polymerization degree, 5 or more, Preferably it is 10 or more, More preferably, it represents an integer of 20 or more. ]

Examples of the polymer or copolymer having a fluorene skeleton of the above formula (1) include the following.
Poly (9,9-di-n-hexylfluorenyl-2,7-diyl) of the following formula (2).
[In formula (2), n represents a degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly [9,9-bis- (2-ethylhexyl) -9H-fluorene-2,7-diyl] of the following formula (3).
[In the formula (3), n represents the degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly (9,9-di-n-octylfluorenyl-2,7-diyl) of the following formula (4).
[In the formula (4), n represents the degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly (9,9-di-n-dodecylfluorenyl-2,7-diyl) of the following formula (5).
[In formula (5), n represents a degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Further, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co-bithiophene] represented by the following formula (6) as a copolymer.
[In the formula (6), m and n represent the degree of polymerization and represent an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alt- (benzo [2,1,3] thiadiazole-4,8-diyl)] of the following formula (7).
[In the formula (7), n represents the degree of polymerization, and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly (9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole) of the following formula (8).
[In the formula (8), n represents the degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly [(9,9-dihexylfluorene-2,7-diyl) -co- (anthracene-9,10-diyl)] of the following formula (9).
[In the formula (9), m and n represent the degree of polymerization and represent an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly [(9,9-dihexylfluorene-2,7-diyl) -co- (9-ethylcarbazole-2,7-diyl)] of the following formula (10).
[In the formula (10), m and n represent the degree of polymerization and represent an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

Poly [(9,9-dihexylfluorene-2,7-diyl) -alt- (2,5-dimethyl-1,4-phenylene)] of the following formula (11).
[In the formula (11), n represents the degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

  Furthermore, a copolymer compound of 2,7-9,9-di-n-octyl fluorangeyl and 2,7-9,9-diisoamyl fluorenediyl is exemplified.

  As the polymer having a fluorene skeleton, poly (9,9-di-n-dodecylfluorenyl-2,7-diyl) represented by the formula (5) is particularly preferable. This is because white light with higher whiteness can be obtained.

  The nitrogen-containing conjugated compound contained in the light emitting layer of the present invention is not particularly limited as long as it forms an exciplex with the conductive polymer that is the light emitting compound, but a voltage was applied. In this case, it plays a role of efficiently transporting holes. Especially, the low molecular compound and high molecular compound which have a triphenylamine skeleton can be used by the point which light-emits favorable exciplex fluorescence.

Examples of the low molecular weight compound having the triphenylamine skeleton include the following formula (12). For example, triphenylamine, N- (4-butylphenyl) -N, N-diphenylamine, N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl]- 4,4′-diamine, N, N′-bis (3-methylphenyl-N, N′-bis (2-naphthyl)-[1,1′-biphenyl] -4,4′-diamine, and the like. In addition, examples of the group that can be substituted on the aromatic ring of the triphenylamine compound include an alkyl group having 1 to 22 carbon atoms and an alkoxy group.
Wherein _(12), n 1 ~n ₃ represents an integer of 1 to _3, Ar 1 to Ar ₃ may all be the or different have the same hydrogen atom, alkyl of 1 to 22 carbon atoms Represents a group selected from a group and an aromatic group. ]

  Other low molecular weight compounds include 4,4 ′, 4 ″ -tris (N, N-diphenyl-amino) triphenylamine (TDATA), 4,4 ′, 4 ″ -tris [N- ( 3-methylphenyl) -N-phenyl-amino] triphenylamine (m-MTDATA), N, N′-bis (3-methylphenyl) -N, N′-diphenyl-1,1′-biphenyl-4, 4′-diamine (TPD), 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl (α-NTPD), 4,4′-bis [N- (4- (N , N-di-m-tolyl) amino) phenyl-N-phenylamino] biphenyl (DNTPD), 4,4 ′, 4 ″ -tris [biphenyl-2-yl (phenyl) amino] triphenylamine, 4,4 ', 4 "-Tris [Bife Ru-4-yl (3-methylphenyl) amino] triphenylamine, 4,4 ′, 4 ″ -tris [9,9-dimethyl-2-fluorenyl (phenyl) amino] triphenylamine, 4,4 ′, Aromatic amines such as 4 ″ -tris [2-naphthyl (phenyl) amino] triphenylamine (2-TNATA), 4,4 ′, 4 ″ -tri (N-carbazolyl) triphenylamine (TCTA) System compounds can also be used.

Among these, m-MTDATA of the following formula (13) is preferable, and exciplex can be well formed with the conductive polymer to emit exciplex fluorescence.

Moreover, as a high molecular compound which has the said triphenylamine skeleton, the high molecular compound shown by following formula (14) or (15) can be used. The hole mobility is high, excitons can be formed efficiently, and white light with high whiteness can be obtained.
[In Formula (14), L is alkylene, n represents a polymerization degree, and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

[In the formula (15), Ar represents a p-phenylene group or an m-phenylene group. n represents a degree of polymerization, and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

As specific examples of the polymer compound having the triphenylamine skeleton, the alkylene group (L) of the above formula (14) may be represented by “—CH (CH ₃ ) —” (the following formula (4)), “—CH ( C ₂ H ₅ ) — ”and the like. In particular, the following formula (16) can be mentioned. This is because white light with higher whiteness can be obtained.
[In the formula (16), n represents the degree of polymerization and represents an integer of 5 or more, preferably 10 or more, more preferably 20 or more. ]

  In order to form an exciplex, the content ratio of the conductive polymer and the nitrogen-containing conjugated compound is preferably 1 to 200 parts by weight of the nitrogen-containing conjugated compound with respect to 100 parts by weight of the conductive polymer. More preferably, it is 120 parts by weight. When the nitrogen-containing conjugated compound is less than the lower limit, the exciplex fluorescence may be reduced and white light may not be obtained. When the nitrogen conjugated compound exceeds the upper limit, the emission color and the emission efficiency may be deteriorated.

  As the layer thickness of the light emitting layer of the present invention, in principle, the light emitting performance does not depend on the film thickness, so that it can be set to any layer thickness. However, in terms of practicality, it is usually 5 nm to 10 mm. A desired layer thickness is applied in the range of. When the layer thickness is smaller than the lower limit value, a short circuit may occur. When the layer thickness exceeds the upper limit value, the efficiency of exciplex formation may be lowered.

At least one of the first electrode and the second electrode constituting the light-emitting electrochemical element of the present invention is a translucent electrode, that is, a transparent electrode. This is for taking out the emitted light. Examples of the material for the transparent electrode include tin oxide, zinc oxide, indium oxide, indium tin oxide, indium oxide / zinc oxide compound, tin oxide / antimony compound, gallium oxide / zinc oxide compound, and metals such as platinum. it can.
The other electrode does not need to be a transparent electrode, for example, aluminum, indium, magnesium, tungsten, titanium, molybdenum, calcium, sodium, potassium, yttrium, lithium, manganese, gold, silver, copper, palladium, platinum Further, metals such as tin, lead, nickel, and alloys of these metals can be used.
In addition, as a 1st, 2nd electrode, ITO (indium tin oxide) which has transparency is preferable, and aluminum is preferable at the point of electroconductivity and economical besides this.
Examples of a method for forming these electrode layers on the transparent substrate include a sputtering method and a vacuum deposition method.

  In the light emitting electrochemical device of the present invention having the above-described configuration, the light emitting layer emits blue light by applying a voltage between the first electrode and the second electrode. In addition, an exciplex is formed between the conductive polymer and the nitrogen-containing conjugated compound, and exciplex fluorescence is emitted. The blue light emission and the exciplex fluorescence of this light emitting layer are mixed and emitted as white light to the outside.

  The light-emitting device of the present invention is configured to include the light-emitting electrochemical element of the present invention and a voltage unit for applying a voltage to the light-emitting electrochemical element. The voltage unit may be either a DC voltage or an AC voltage.

  Next, an example of a method for producing the light-emitting electrochemical element of the present invention will be described with reference to FIG.

A light-emitting electrochemical element 10 shown in FIG. 1 includes a conductive polymer, an electrolyte, a supporting salt, and a nitrogen-containing conjugated compound on the surface of an ITO electrode or the like provided as a first electrode (anode) 1 on a substrate such as glass. A dispersion solution dissolved and dispersed in a solvent is applied by, for example, a spin coat film forming method, and the solvent is removed by drying to laminate the light emitting layer 2. Here, the solvent for the dispersion solution is not particularly limited as long as it dissolves each constituent component. For example, a solvent such as chloroform, cyclohexanone, toluene, and a mixed solvent can be used.
Subsequently, aluminum as the second electrode (cathode) 3 is laminated on the light emitting layer 2 by, for example, vapor deposition and film formation by a vacuum vapor deposition method.
The light-emitting electrochemical element 10 can be manufactured as described above.
In the above description, the first electrode is an anode and the second electrode is a cathode. However, in a light-emitting electrochemical element, it is not necessary to fix the electrode in this way. For example, the same material is used for the first electrode and the second electrode. The voltage can be applied by arbitrarily determining the anode and the cathode.

The element characteristics of the light-emitting electrochemical element 10 of the present invention can be evaluated by luminance-voltage (LV) characteristics, EL spectrum diagrams, PL spectrum diagrams, and chromaticity diagrams (chromaticity coordinates).
In the LV characteristic evaluation, the relationship between the drive voltage and the luminance of the emitted light can be evaluated. In the EL spectrum diagram, the details of the emission color can be grasped by the emission intensity for each wavelength when a voltage is applied. In the PL spectrum diagram, the details of the emission color can be grasped by the emission intensity for each wavelength. Furthermore, the luminescent color can be expressed by the numerical value of the xy coordinates using a chromaticity diagram, and the degree of whiteness of white light which is an object of the present invention can be evaluated by the numerical value of the xy coordinates.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<Light emitting layer: Composition 1>
As the composition 1, the following components (A1) to (A4) were mixed at the blending ratio shown in Table 1, and dissolved in the following chloroform / cyclohexanone mixed solvent.
(A1) Conductive polymer: Poly (9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) (PFD) of the above formula (5) (Poly (9,9-di-) n-dodecylfluorenyl-2,7-diyl)) was used.
(A2) Nitrogen-containing conjugated compound: 4,4 ′, 4 ″ -tris [phenyl (m-tolyl) amino] triphenylamine (m-MTDATA)
(A3) Electrolyte: Polyethylene oxide (A4) Supporting salt: KCF ₃ SO ₃

<Light-emitting electrochemical element: Preparation of element A>
An ITO electrode was provided as a first electrode (anode) 1 on a glass substrate, and UV ozone cleaning was performed. Thereafter, a solution 14.6 (mg / mL solvent) in which the composition 1 is dissolved in a chloroform / cyclohexanone (1.08: 1.0) mixed solvent is applied onto the first electrode 1 by a spin coating film forming method. Subsequently, the mixed solvent was removed by drying, and a light emitting layer 2 having a thickness of 150 nm was laminated. Further, aluminum was vacuum-deposited on the light emitting layer 2 to laminate a second electrode (cathode) 3 having a thickness of 100 nm.
Device A was fabricated as described above. The obtained device A was subjected to luminescent color evaluation using LV characteristics, EL spectrum, PL spectrum, and chromaticity diagram. FIG. 2 shows the LV characteristics, FIG. 3 shows the EL spectrum, FIG. 4 shows the PL spectrum, FIG. 5 shows the chromaticity diagram, and Table 2 shows the xy coordinates of the chromaticity coordinates on the chromaticity diagram.

Examples 2 and 3
<Light emitting layer: Compositions 2 and 3>
As the compositions 2 and 3, the above components (A1) to (A4) were mixed at the blending ratio shown in Table 1, and dissolved in a chloroform / cyclohexanone mixed solvent in the same manner as the composition 1.
<Light-emitting electrochemical element: Preparation of elements B and C>
Elements B and C were prepared in the same manner as in Example 1 except that the light emitting layer was changed to compositions 2 and 3 in place of the composition 1 of Example 1, and evaluated in the same manner. The results are shown in FIGS.

Comparative Example 1
<Light emitting layer: Composition 4>
As the composition 4, the components (A1), (A2) and (A4) were mixed at the blending ratio shown in Table 1 and dissolved in a chloroform / cyclohexanone mixed solvent in the same manner as the composition 1.
<Light-emitting electrochemical element: Preparation of element D>
A device D was prepared in the same manner as in Example 1 except that the light emitting layer was changed to the composition 4 instead of the composition 1 of Example 1, and evaluated in the same manner. The results are shown in FIGS.

It can be seen from the chromaticity diagram of FIG. 5 that all of the light-emitting electrochemical elements A to C emit white light at a drive voltage of 7.5 V to 8.5 V. In addition, it can be seen from FIG. 2 that the light emission start voltage is 3.5 to 4.5 V, and light emission is started at a low voltage. Further, when the EL spectrum diagram of FIG. 3 is compared with the PL spectrum diagram of FIG. 4, a shoulder peak is observed in the wavelength of 600 nm to 700 nm showing red emission in the EL spectrum diagram 3, but in the PL spectrum diagram 4, the wavelength: 600 nm to Since no fluorescence appears at 700 nm, it can be seen that an exciplex is formed between PFD and m-MTDATA to emit light. From the chromaticity diagram of FIG. 5, it can be seen that white light emission almost unlimited in white is obtained in all of the elements A to C.
The so-called pure white light has a chromaticity coordinate of (x, y) = (0.33, 0.33).

  1 first electrode, 2 light emitting layer, 3 second electrode

Claims (9)

In the light emitting electrochemical device in which the first electrode, the light emitting layer, and the second electrode are laminated in this order,
The light emitting layer contains a conductive polymer, an electrolyte, a supporting salt and a nitrogen-containing conjugated compound,
By applying a voltage between the first electrode and the second electrode, the conductive polymer emits blue light, and an exciplex is formed between the conductive polymer and the nitrogen-containing conjugated compound. Emits exciplex fluorescence,
Luminescent electrochemical element. The conductive polymer is a polymer having a fluorene skeleton represented by the formula (1).
The light-emitting electrochemical device according to claim 1.
[In Formula (1), R is a C1-C20 alkyl group, m shows a polymerization degree and represents the integer of 5 or more. ] The electrolyte contains polyalkylene oxide;
The light-emitting electrochemical device according to claim 1 or 2. The nitrogen-containing conjugated compound is a compound having a triphenylamine skeleton.
The light-emitting electrochemical element according to any one of claims 1 to 3. The conductive polymer contains poly (9,9-di-n-dodecylfluorene-2,7-diyl),
The light-emitting electrochemical element according to any one of claims 1 to 4. The electrolyte contains polyethylene oxide,
The light-emitting electrochemical element according to any one of claims 1 to 5. The nitrogen-containing conjugated compound contains 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] triphenylamine (m-MTDATA).
The light-emitting electrochemical element according to any one of claims 1 to 6. The content of the nitrogen-containing conjugated compound is 1 to 200 parts by weight with respect to 100 parts by weight of the conductive polymer.
The light-emitting electrochemical element according to any one of claims 1 to 7. A light emitting device comprising: the light emitting electrochemical element according to claim 1; and a voltage unit that applies a voltage between the first electrode and the second electrode of the light emitting electrochemical element.