CN101459225B

CN101459225B - Device for improving brightness of organic electroluminescence by exciton state inhibition

Info

Publication number: CN101459225B
Application number: CN2009100762057A
Authority: CN
Inventors: 徐征; 赵谡玲; 张福俊; 徐叙瑢
Original assignee: Beijing Jiaotong University
Current assignee: Beijing Jiaotong University
Priority date: 2009-01-05
Filing date: 2009-01-05
Publication date: 2010-06-02
Anticipated expiration: 2029-01-05
Also published as: CN101459225A

Abstract

The invention discloses a device capable of inhabiting the exciton state to improve electroluminescent brightness, which structurally comprises Al/SiO2/Au/P-type OEL/ITO, wherein a semi-permeable electron Au electrode (3) is arranged between a SiO2 layer (4) and a P-type OEL layer (2), the SiO2 layer (4) and the P-type OEL layer (2) are respectively excited by two independent direct current sources, then the excitation energy of a hot-electron is led to be large enough to permeate through the Au electrode to impact and excite the P-type OEL, further, the thickness of the SiO2 layer is 500nm, voltage V1 ranges from 50 v to 200 v, the thickness of the P-type OEL layer is 30 nm, voltage V2 ranges from 3 v to 15 v, thereby completely ionizing excitons of the P-type OEL, and realizing lightingof the P-type OEL. Only extended state luminescence is obtained in the invention, which is used to increase electric field inductive organic electroluminescent quantum efficiency and brightness. Whenthe voltage applied to the SiO2 layer, extended state luminescence is raised monotonically.

Description

The device that suppresses improving brightness of organic electroluminescence by exciton state

Technical field

The present invention relates to a kind of quantum efficiency that improves organic field luminescence, thereby improve the device that overall brightness is induced in the field.It is mainly used in electric field and induces the luminous quantum efficiency of the raising of organic field luminescence quantum efficiency and brightness, the used organic field luminescence screen of automatically controlled flat panel display and raising of brightness etc.

Background technology

Often be the luminous of exciton in the organic field luminescence, it is luminous and triplet state is luminous forms by singlet.Statistics shows and exciting the back molecule to be in the singlet of excitation state and the proportion of triplet state is 1: 3, and general singlet is luminous, and triplet state is not luminous.As utilize the optical excitation electronic spin that then is excited to keep initial value constant, and its exciton of forming is exactly a singlet like this, thus in luminescence generated by light, the luminous quantum efficiency of singlet can reach 1.But in organic field luminescence, electronics and hole are to inject from comparative electrode independently, their spin-spin relations are pressed statistical law, are singlets and the ratio of triplet state number is 1: 3, like this, the transition of singlet only accounts for 1/4 of whole transition, thereby its luminous quantum efficiency maximum is 1/4, promptly maximum be luminescence generated by light quantum efficiency 1/4, thereby popular a kind of viewpoint, promptly the quantum efficiency of organic field luminescence is equal to or less than 1/4 of its luminescence generated by light.

The life-span of singlet is shorter, so in a unit interval, when triplet state also was in excitation state, it can repeatedly be excited, and is repeatedly luminous, promptly so-called circulation excites, and it makes the luminous grow of singlet.Someone utilizes these characteristics to do experiment in inorganic light-emitting, the luminous expected results that is enhanced, and under the situation of mixed activation, the restriction of organic field luminescence 1/4 can be broken.As not being mixed activation, just there has not been advantage, and for as long as the generation of organic field luminescence is to inject the compound mixed activation that just can not get in back from different electrodes respectively by electronics and hole.So, break 1/4 restriction, must look for another way, just to excite be not all right in circulation.

Summary of the invention

Principle of the present invention: target of the present invention is to use a kind of effective ways, suppresses the luminous of the not luminous exciton that accounts for main body in the organic field luminescence, and luminous quantum efficiency and brightness are improved.Luminous singlet exciton is arranged in the organic field luminescence, non-luminous triplet excitons is arranged again, and triplet excitons has accounted for very high proportion 75%.If exciton is in than highly excited level, the excitation state of these two kinds of excitons all will enter and can be with, and become the expansion attitude, and such singlet and triplet state be degeneracy, thereby they can send light by the rule of recombination luminescence.By this standard close examination organic field luminescence, the probability of recombination luminescence increases, and luminous quantum efficiency and brightness all can improve.

Technical scheme of the present invention

A kind of device that suppresses improving brightness of organic electroluminescence by exciton state, the structure of this device:

Al/SiO ₂/ Au/P type OEL/ITO

At SiO ₂The layer and P type OEL between is the Au electrode of a semi-transparent electronics, respectively with two independently DC power supply excite SiO ₂Layer and P type OEL layer; Make the Au electrode of the excitation energy of hot electron, collision excitation P type OEL layer through semi-transparent electronics;

SiO ₂The thick of layer is 500nm, voltage V ₁Be 50～200V;

The thickness 30nm of P type OEL layer, voltage V ₂Be 3～15V, realize that P type OEL is luminous.

Described Al/SiO ₂Adopt the FEA/ vacuum chamber, its structure:

FEA/ vacuum chamber/Au/P type OEL/ITO

Described P type OEL layer is polyhenylene acetylene (PPV) or gathers (2-methoxyl group-5-(2-ethyl hexyl oxy)) to phenylacetylene (MEH-PPV).

Beneficial effect of the present invention:

Have only the expansion attitude of luminous organic material luminous in the organic light emission that is obtained.It no longer is subjected to the negative effect of non-luminous triplet state, and luminous quantum efficiency can improve, and luminous intensity is strengthened.Be added in SiO ₂When the voltage of layer improves, luminous dull rising of expansion attitude.

Description of drawings

Fig. 1 suppresses one of device architecture schematic diagram of improving brightness of organic electroluminescence by exciton state.

Fig. 2 suppress improving brightness of organic electroluminescence by exciton state the device architecture schematic diagram two.

Among the figure: ITO1, P type OEL layer 2, Au electrode 3, SiO ₂Layer 4, Al electrode 5, vacuum chamber 6, FEA 7.

Embodiment

The invention will be further described in conjunction with the accompanying drawings:

The core technology of device is to suppress exciton state, thereby avoids luminous organic material to form the negative effect of exciton, improves the brightness of organic field luminescence.

The device architecture that suppresses improving brightness of organic electroluminescence by exciton state is:

Embodiment one

Al/SiO ₂/Au/PPV/ITO

P type OEL layer 2 adopts PPV.

At SiO ₂The Au electrode 3 of semi-transparent electronics between layer 4 and the PPV, respectively with two independently DC power supply excite SiO ₂Layer and PPV layer; Allow the hot electron of enough excitation energies see through the Au electrode 3 of semi-transparent electronics, collision excitation PPV layer.

SiO ₂The thick of layer 4 is 500nm, voltage V ₁Be 50V.

The thickness 30nm of PPV is added in the voltage V on the PPV ₂Be 3V, both guaranteed the hole injection, realize that PPV is luminous, make the electronics that loses excitation energy participate in the into electroluminescent of PPV again.

The thickness of Au electrode is 25nm, both can see through electronics, can be used as electrode again.

Embodiment two

Al/SiO ₂/Au/MEH-PPV/ITO

P type OEL layer 2 adopts MEH-PPV.

At SiO ₂The Au electrode 3 of semi-transparent electronics between layer 4 and the MEH-PPV, respectively with two independently DC power supply excite SiO ₂Layer and MEH-PPV layer; Allow the hot electron of enough excitation energies see through the Au electrode 3 of semi-transparent electronics, collision excitation MEH-PPV layer.

SiO ₂The thick of layer 4 is 500nm, voltage V ₁Be 200V.

The thickness 30nm of PPV is added in the voltage V on the PPV ₂Be 15V, both guaranteed the hole injection, realize that MEH-PPV is luminous, make the electronics that loses excitation energy participate in the into electroluminescent of MEH-PPV again.

The thickness of the Au electrode of semi-transparent electronics is 25nm, both can see through electronics, can be used as electrode again.

Embodiment three

FEA/ vacuum chamber/Au/PPV/ITO

P type OEL layer 2 adopts PPV.

The outside that is deposited on the PPV on the ITO is the Au electrode 3 of a semi-transparent electronics, respectively with two independently direct voltage excite FEA layer and PPV; Make the excitation energy of the electronics that in vacuum chamber, quickens be enough to see through Au electrode 3 back collision excitation PPV layers.

Vacuum chamber thickness is 100 μ m, voltage V ₁Be 100V.

The thickness 30nm of PPV, PPV institute making alive is V ₂Be 15V, realize that PPV is luminous.

The thickness of the Au electrode of semi-transparent electronics is 25nm, can see through electronics, can be used as electrode again.

Embodiment four

FEA/ vacuum chamber/Au/MEH-PPV/ITO

P type OEL layer 2 adopts MEH-PPV.

The outside that is deposited on the MEH-PPV on the ITO is the Au electrode 3 of a semi-transparent electronics, respectively with two independently direct voltage excite FEA layer and MEH-PPV; Make the excitation energy of the electronics that in vacuum chamber, quickens be enough to see through Au electrode 3 back collision excitation MEH-PPV layers.

Vacuum chamber thickness is 100 μ m, voltage V ₁Be 50V.

The thickness 30nm of MEH-PPV, PPV institute making alive is V ₂Be 3V, realize that MEH-PPV is luminous.

Claims

1. a device that suppresses improving brightness of organic electroluminescence by exciton state is characterized in that, this device architecture is: FEA/ vacuum chamber/Au/P type OEL/ITO

Wherein the Au electrode is the electrode of semi-transparent electronics, utilize respectively two independently DC power supply excite FEA layer and P type OEL layer, make the excitation energy of the electronics that in vacuum chamber, quickens be enough to see through collision excitation P type OEL layer behind the Au electrode of semi-transparent electronics;

Vacuum chamber thickness is 500nm; The DC current source positive pole that puts on the FEA layer connects the Au electrode, and negative pole connects the FEA layer, and voltage V ₁Be 50-200V; The thickness of P type OEL layer is 30nm, and the dc power anode that puts on the P type OEL meets ITO, and negative pole meets Au, and voltage V ₂Be 3-15V.

2. a kind of device that suppresses improving brightness of organic electroluminescence by exciton state according to claim 1 is characterized in that, P type OEL layer is polyhenylene acetylene or gathers (2-methoxyl group-5-(2-ethyl hexyl oxy)) to phenylacetylene.