CN101449626A - El device - Google Patents

El device Download PDF

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Publication number
CN101449626A
CN101449626A CNA2007800183208A CN200780018320A CN101449626A CN 101449626 A CN101449626 A CN 101449626A CN A2007800183208 A CNA2007800183208 A CN A2007800183208A CN 200780018320 A CN200780018320 A CN 200780018320A CN 101449626 A CN101449626 A CN 101449626A
Authority
CN
China
Prior art keywords
shell
nuclear part
quantum dot
luminous
electroluminescent cell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CNA2007800183208A
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Chinese (zh)
Inventor
池西美穗
小林哲
井口由纪
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoya Corp
Original Assignee
Hoya Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hoya Corp filed Critical Hoya Corp
Publication of CN101449626A publication Critical patent/CN101449626A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/56—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing sulfur
    • C09K11/562—Chalcogenides
    • C09K11/565—Chalcogenides with zinc cadmium
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/88—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing selenium, tellurium or unspecified chalcogen elements
    • C09K11/881—Chalcogenides
    • C09K11/883—Chalcogenides with zinc or cadmium

Abstract

The present invention discloses an EL device which emits light when an alternating current field is applied thereto. In the EL device, a light-emitting layer contains a quantum dot having a core-shell structure wherein the surface of a core portion is covered with a shell layer. The shell layer is made of a material having a wider band gap than the material for the core portion, and the thickness of the shell layer is 5-100 nm.

Description

Electroluminescent cell
Technical field
The present invention relates to the EL element (electroluminescent cell) of the type luminous by implementing AC field that charge carrier is injected luminous particle.
Background technology
Apply AC field and to luminous particle son inject charge carrier with luminous EL element owing to can obtain high luminosity, so by primary study.As such EL element, the structure of patent documentation 1 record is for example arranged.
The EL element of patent documentation 1 is laminated to few one deck dielectric layer and luminescent layer between two electrodes, in this luminescent layer, the second semiconductor microactuator particle is dispersed in the continuous phase that is made of first semiconductor.If this EL element is applied AC field, then the charge carrier that produces from first semiconductor impacts the second semi-conductive particulate, thereby the second semi-conductive particulate excites, and is luminous when returning ground state.
Patent documentation 1:(Japan) spy opens the 2003-249373 communique
Patent documentation 2:(Japan) spy opens the 2003-173878 communique
But in the EL element of patent documentation 1, charge carrier is low to the efficient that the second semi-conductive particulate injects, and can not realize the luminous efficiency of expecting.This is owing to following reason is caused, that is, and and the reduction of at random, first semiconductor of the charge carrier that the impurity that luminescent layer was sneaked into when forming causes and low " quantum limitation effect " that causes of continuity on the second semi-conductive atomic border.
Summary of the invention
A first aspect of the present invention provides a kind of EL element, the quantum dot of the nucleocapsid structure that the surface that luminescent layer contains nuclear part is covered by shell, luminous by applying AC field, wherein, shell is made of the big material of material of band gap than the nuclear part, and the thickness of shell is 5nm～100nm.
A second aspect of the present invention provides a kind of EL element, the quantum dot of the nucleocapsid structure that the surface that luminescent layer contains nuclear part is covered by shell, luminous by applying AC field, wherein, shell is made of the big material of material of band gap than described nuclear part, and luminous by the intrinsic charge charge carrier that is present in shell to the supply of nuclear part.
Third aspect present invention, first or the basis of second aspect on, luminescent layer mixes with jointing material by the particle with nucleocapsid structure and constitutes.
Fourth aspect present invention, on the basis of the third aspect, jointing material is made of dielectric.
Fifth aspect present invention, on the basis of first～the 3rd either side, quantum dot has organic side chain in the outside of shell.
Sixth aspect present invention, on the basis of first～the 5th either side, the particle diameter of nuclear part is 1～10nm.
According to the present invention, the quantum dot of the nucleocapsid structure by using the thick shell of amount, part and continuity as the interface of the shell of carrier injection layer are examined in the influence that impurity in the time of formed by luminescent layer is sneaked into and can guaranteeing, can inject the nuclear part by the charge carrier that simple manufacturing method will be present in shell effectively.Thus, can realize high luminous efficiency, and utilize the original high luminosity of nuclear part that contains quantum dot.
Embodiment
Below, describe embodiments of the present invention in detail.
The EL element of present embodiment (electroluminescent cell) is the structure that stacks gradually first insulating barrier, luminescent layer, second insulating barrier between pair of electrodes.
As pair of electrodes, for example can use Au (gold) metal electrode and ITO (indium tin oxide) transparency electrode.The Au electrode is film forming by the vacuum vapour deposition in common use resistance heating evaporation source.The ITO electrode uses the electrode of film forming on glass substrate in advance, but also can form by other known method such as sputtering methods.
Two insulating barriers for example can form silicon nitride, tantalum pentoxide, Si oxide, yttrium oxide, aluminium oxide, hafnium oxide, palladium tantalum pentoxide by sputtering method etc.
Luminescent layer preferably only is made of the quantum dot of nucleocapsid structure.Like this, do not need to make particle to be distributed to operation in the adhesive equably, and reduce the possibility that impurity is sneaked into.But, only in the quantum dot of nucleocapsid structure, be difficult to form under the situation of luminescent layer, can be by mix the fitting tightly property that improves with insulating barrier with adhesive.
The quantum dot of nucleocapsid structure is the structure that the surface of nuclear part is covered by shell.
The nuclear part is except CdSe, also can use for example material formation of CdS, PdSe, HgTe, CdTe, InP, GaP, InGaP, GaAs, InGaN, GaN, ZnO, CsSe, ZnSe, ZnTe and their mixed crystal formation, suitably determine material and particle diameter according to the emission wavelength that EL element requires.The particle diameter of nuclear part is preferably selected in the scope of 1～10nm, utilizes known method (for example wet chemistry synthetic method (liquid phase synthesizing method), laser abrasion method) to form spherical.
Shell uses for example by ZnS, ZnSe, CaS, SrS, BaS, CaGa 2S 4, SrGa 2S 4, ZnMgS 2, BaAl 2S 4And the big material of material of the material of their mixed crystal formation and band gap ratio nuclear part, for example by liquid phase synthesizing method, vapour deposition method, the deposited method of suspended particulates (aerosol), spraying process formation.The quantum dot that is obtained by liquid phase synthesizing method has the ligand that is made of organic side chain usually around shell, to improve the solvent dispersiveness.In the EL element in the present embodiment, because with the shell of intrinsic charge charge carrier around the supply source that the nuclear part is supplied with is formed in the nuclear part, so the border continuity of each quantum dot shell does not each other almost have help to luminous efficiency.Therefore, around shell, exist under the state of organic side chain, quantum dot can be used for luminescent layer.In addition, obviously be to supply with to the intrinsic charge charge carrier that nuclear part is supplied with, but also can supply with from the shell of the quantum dot of adjacent quantum dot or distance from the shell that is formed at around the nuclear part.
As adhesive, from applying the viewpoint of AC field easily, preferred dielectric for example can use epoxy resin, pvdf resin, cyano ethyl cellulose, cyano ethyl polyvinyl alcohol, polyethylene, polypropylene, polystyrene resins, silicone resin.Adhesive for example can pass through spin-coating method, wire mark method, dip coating method, the better simply film build method formation of spraying process geometric ratio.
The EL element of present embodiment by to apply between pair of electrodes AC field nuclear part inject charge carrier be excited, luminous, but owing to be defined in the structure that the charge carrier of injection is present in shell, so shell can be formed the regulation thickness, and produce AC field with specified period.At this moment, the regulation thickness of shell is selected from the scope of 5nm～100nm, and specified period can be selected with the combination of regulation thickness, can only injecting the charge carrier that is present in shell to the nuclear part.Like this, inject at the charge carrier that only will be present in shell under the situation of the nuclear part of being surrounded by shell, the at random of the charge carrier that causes because of impurity can be prevented, thus, the EL element that realizes high luminous efficiency and utilize the high luminosity of nuclear part itself can be provided.In addition, in the EL element of so having set the shell thickness, also can be to supply with the nuclear part from the intrinsic charge charge carrier of the shell of adjacent or remote quantum dot by the cycle that changes AC field.In addition, by changing the cycle of AC field, the luminosity of EL element is changed.
Embodiment 1
The embodiment 1 of above-mentioned execution mode is described.
The ITO electrode uses structure (the sub-size ≈ thickness of crystallization: about 100nm, surface roughness Ra: about 50nm) of film forming on glass substrate.On the glass substrate of this band ITO, form TaO as insulating barrier xFilm uses the high frequency magnetic control sputtering device that substrate is remained on normal temperature and makes its growth.The thickness of insulating barrier is about 400nm.And, the dispersion liquid that spin coating is following also makes its drying and forming-film, and described dispersion liquid has is dispersed in the cyano ethyl cellulose solution (adhesive) CdSe (nuclear part)/ZnS (shell) quantum dot that has carried out the core/shell structure of surface modification by TOPO (trioctyl phosphine oxide).Substrate temperature when dry is selected between can be about room temperature～200 ℃, but is preferably below 100 ℃.This be because, when temperature is too high, the luminescence activity deterioration of quantum dot.The thickness of accumulating film is about 1 μ m.And, insulating barrier TaO xFilm grows into the thickness of about 400nm, and then uses shadow shield, utilizes vacuum vapour deposition to form the Au electrode of the about 500nm of thickness.
Like this, according to TaO x/ (CdSe (the about 5.2nm in nuclear footpath)/ZnS (the thick about 15nm of shell) quantum dot-cyanethyl cellulose adhesive)/TaO xThe sequential cascade film of/Au is made EL element.The illuminant colour that can access quantized level with the nuclear of quantum dot and be origin is EL spectrum (to be the independent peak value at center) near the 600nm.
The determination method of luminescent spectrum and intensity then, is described.The luminescence generated by light of EL element (PL) is an exciting light with the monochromatic light of wavelength 350nm, uses Japanese beam split system sepectrophotofluorometer PF-6500DS to measure.The temperature of sample all is a room temperature during mensuration.At this moment, also the PL spectrum of the raw material dispersion soln that uses is measured.The mensuration of EL is by carrying out applying low-frequency sine voltage between ITO electrode, Au electrode.The Au electrode forms the square that size in length and breadth is respectively 1mm, via In two electrodes is applied frequency f=100kHz (cycle 0.01ms), voltage V=100V PpVoltage (AC field), measure electric current and luminous (EL), the result observes luminous under about 600nm.From the luminous detector that imports sepectrophotofluorometer by optical fiber into that the glass substrate face of element penetrates, carry out photometry, the result, the PL spectrum of element and the PL spectrum of material solution are roughly consistent.
Embodiment 2
In embodiment 2, except replacing in the foregoing description 1, having CdSe (nuclear part)/ZnS (shell) quantum dot that has carried out the core/shell structure of surface modification by TOPO (trioctyl phosphine oxide), use has by TOPO have been undertaken forming EL element similarly to Example 1 beyond InP (nuclear part)/ZnSe (shell) quantum dot of the core/shell structure of surface modification.The nuclear of the quantum dot that uses among the embodiment 2 directly is about 2.6nm, the thick 12nm that is about of shell.Apply frequency f=10kHz, voltage V=150V PpVoltage, result, luminous under the about 540nm of point of observation.
Describe the present invention with reference to above-mentioned execution mode, but the invention is not restricted to above-mentioned execution mode, in purpose that improves or thought range of the present invention, can improve or change.

Claims (6)

  1. The quantum dot of the nucleocapsid structure that the surface that 1, a kind of electroluminescent cell, its luminescent layer contain nuclear part is covered by shell, luminous by applying AC field, it is characterized in that,
    Described shell is made of the big material of material of band gap than described nuclear part,
    The thickness of described shell is 5nm～100nm.
  2. The quantum dot of the nucleocapsid structure that the surface that 2, a kind of electroluminescent cell, its luminescent layer contain nuclear part is covered by shell, luminous by applying AC field, it is characterized in that,
    Described shell is made of the big material of material of band gap than described nuclear part,
    Luminous by the intrinsic charge charge carrier that is present in described shell to the supply of described nuclear part.
  3. 3, electroluminescent cell as claimed in claim 1 or 2 is characterized in that, described luminescent layer mixes the particle of described nucleocapsid structure and constitutes with jointing material.
  4. 4, electroluminescent cell as claimed in claim 3 is characterized in that, described jointing material is made of dielectric.
  5. 5, as each described electroluminescent cell in the claim 1～3, it is characterized in that described quantum dot has organic side chain in the outside of described shell.
  6. As any described electroluminescent cell in the claim 1～5, it is characterized in that 6, the particle diameter of described nuclear part is 1～10nm.
CNA2007800183208A 2006-07-28 2007-07-13 El device Pending CN101449626A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP205625/2006 2006-07-28
JP2006205625 2006-07-28

Publications (1)

Publication Number Publication Date
CN101449626A true CN101449626A (en) 2009-06-03

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JP (1) JPWO2008013069A1 (en)
CN (1) CN101449626A (en)
WO (1) WO2008013069A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103715370A (en) * 2013-12-26 2014-04-09 合肥京东方光电科技有限公司 Microcapsule and organic electroluminescence displaying device with microcapsule
CN104701430A (en) * 2015-02-10 2015-06-10 河南大学 Method for prolonging service life of quantum dot LED

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015107790A1 (en) * 2014-01-16 2015-07-23 コニカミノルタ株式会社 Electroluminescent element
EP3101089B1 (en) 2014-01-29 2019-03-13 Daicel Corporation Quantum dot conjugate, wavelength conversion element comprising conjugate, photoelectric conversion device, and solar cell
US20220158108A1 (en) * 2019-02-27 2022-05-19 Sharp Kabushiki Kaisha Light-emitting element and display device using light-emitting element

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
JP3887984B2 (en) * 1999-02-05 2007-02-28 松下電器産業株式会社 Multicolor light emitting dispersion type EL lamp
WO2003030227A2 (en) * 2001-10-02 2003-04-10 Quantum Dot Corporation Method of semiconductor nanoparticle synthesis
EP1603991A1 (en) * 2003-03-11 2005-12-14 Philips Intellectual Property & Standards GmbH Electroluminescent device with quantum dots
JP2005132947A (en) * 2003-10-30 2005-05-26 Konica Minolta Medical & Graphic Inc Fluorophor for inorganic electroluminescence, method for producing the same, and inorganic electroluminescent device
JP4781821B2 (en) * 2004-01-23 2011-09-28 Ｈｏｙａ株式会社 Quantum dot dispersed light emitting device and method for manufacturing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103715370A (en) * 2013-12-26 2014-04-09 合肥京东方光电科技有限公司 Microcapsule and organic electroluminescence displaying device with microcapsule
WO2015096324A1 (en) * 2013-12-26 2015-07-02 京东方科技集团股份有限公司 Light-emitting microcapsule, preparation method thereof and organic electroluminescent display apparatus comprising light-emitting microcapsule
CN103715370B (en) * 2013-12-26 2017-08-08 合肥京东方光电科技有限公司 The preparation method of microcapsules
US10312463B2 (en) 2013-12-26 2019-06-04 Boe Technology Group Co., Ltd. Light emitting microcapsule, method of preparing the same and OLED display device comprising the same
CN104701430A (en) * 2015-02-10 2015-06-10 河南大学 Method for prolonging service life of quantum dot LED

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WO2008013069A1 (en) 2008-01-31

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Open date: 20090603