CN101885704A - Electron transport material and organic electroluminescence device thereof - Google Patents

Electron transport material and organic electroluminescence device thereof Download PDF

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CN101885704A
CN101885704A CN2009100839097A CN200910083909A CN101885704A CN 101885704 A CN101885704 A CN 101885704A CN 2009100839097 A CN2009100839097 A CN 2009100839097A CN 200910083909 A CN200910083909 A CN 200910083909A CN 101885704 A CN101885704 A CN 101885704A
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hydroxyl
aluminium
nitroquinoline
organic electroluminescence
electroluminescence device
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陈志坚
罗方闻
肖立新
孔胜
段来强
龚旗煌
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Peking University
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Peking University
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Abstract

The invention discloses an electron transport material and an organic electroluminescence device thereof. The electron transport material is 8-hydroxyl-5-hydroxyquinoline aluminum coordination compound. The electron transport material has good electronic transmission characteristics, can be used as an electron transport layer alone or in combination with other organic electron transport materials, and is applied to the organic electroluminescence device. With nitro groups of strong electron-withdrawing group, the 8-hydroxyl-5-hydroxyquinoline aluminum has better electronic transmission characteristics than Alq3, has LUMO energy level between those of Alq3 and LiF/Al, and can be used as a buffer layer to make transmission of two kinds of current carriers (electrons and holes) in the device more balanced so as to improve light output efficiency of the device, and particularly can effectively reduce light starting voltage of the device and improve luminosity of the device in a low pressure area (3 to 8.5 V).

Description

A kind of electron transport material and organic electroluminescence device thereof
Technical field
The invention belongs to organic electroluminescence device (OLED) field, be specifically related to a kind of organic materials and corresponding OLED device with better electron transport property.
Background technology
The structure of general OLED device is anode, hole transmission layer, luminescent layer, electron transfer layer, negative electrode successively.When the making alive of device two ends, hole and electronics inject from anode, negative electrode respectively, and transmission is compounded to form exciton at luminescent layer, exciton de excitation radioluminescence.
In existing organic semiconductor material, usually hole mobile material will be greatly faster than the transmission speed of electron transport material for electronics for the transmission speed in hole, thereby in electroluminescent device, be difficult to realize the charge transfer balance, charge bonded efficient is very low, cause device to open bright voltage higher (4-5V), device is on the low side in low pressure area (3-8V) brightness, therefore improves device can improve device greatly in the ability aspect electronics injection and the transmission photoelectric characteristic.The related work of having reported comprises: document 1 (L.S.Hung, C.W.Tang, M.G.Mason. " Enhanced electron injection in organicelectroluminescence devices using an Al/LiF electrode ", APPIED PHYSICS LETTERS, 1997,70,152.) find between organic electron transport layer and cathodic metal aluminium (Al), to insert one deck LiF as electron injecting layer, under suitable thickness (0.5nm), can improve the electronics injection efficiency of device, improve luminous efficiency; Document 2 (YouichiSakamoto, Toshiyasu Suzuki, Atsushi Miura, Hisayoshi Fujikawa, Shizuo Tokito, and YasunoriTaga. " Synthesis; Characterization; and Electron-Transport Property of Perfluorinated PhenyleneDendrimers ", J.Am.Chem.Soc 122 (2000), and 1832.) at Alq 3And the phenyl fluorochemical that inserts one deck 20 nanometers between the LiF/Al improves the luminescent properties of device as electric transmission and hole blocking layer; Document 3 (Oh HY, Lee C, LeeS, " Efficient blue organic light-emitting diodes using newly-developed pyrene-based electrontransport materials ", ORGANIC ELECTRONICS, 2009,10,163-169) proposed a kind of pyrene series organic electronic transport material, found that it is than conditional electronic transport material Alq 3Have better electronic transmission performance, and easier and luminescent layer realization energy level coupling.
Summary of the invention
The purpose of this invention is to provide a kind of new organic electronic transport material, and utilize this organic materials to improve the performance of organic electro-optic device.
Organic electronic transport material provided by the present invention is title complex 8-hydroxyl-5-nitroquinoline aluminium (tris (8-hydroxy-5-nitroquinoline)-quinoline-aluminium), it has stronger electron transport property, be applied to effective bright voltage that opens that reduces device in the OLED device as electron transfer layer, improve the luminosity of low pressure area.
The structural formula of title complex 8-hydroxyl-5-nitroquinoline aluminium is shown in the following formula:
Figure B2009100839097D0000021
The preparation method of 8-hydroxyl-5-nitroquinoline aluminium is as follows:
With AlCl 3Be dissolved in respectively in the dehydrated alcohol with 8-hydroxyl-5-nitroquinoline, (referred to AlCl in 1: 3 in molar ratio then 3: 8-hydroxyl-5-nitroquinoline) with AlCl 3Solution dropwise joins 8-hydroxyl-5-nitroquinoline solution, at room temperature stirs then 8-10 hour, filters the solid that obtains of purifying at last and is 8-hydroxyl-5-nitroquinoline aluminium.
The present invention also provides a kind of organic electroluminescence device, comprises anode, hole transmission layer, luminescent layer and negative electrode, it is characterized in that, comprises also that between luminescent layer and negative electrode with 8-hydroxyl-5-nitroquinoline aluminium be the electron transfer layer of material.
Above-mentioned device in actual applications, according to different luminescent materials, can select 8-hydroxyl-5-nitroquinoline aluminium separately as electron transfer layer or with other materials jointly as electron transfer layer.When its during separately as electron transfer layer, promptly the electron transfer layer of device is one deck 8-hydroxyl-5-nitroquinoline aluminium film, its thickness is generally 10-50nm, preferred 30-40nm; When with other materials during, be at other organic electronic transport materials (Alq for example jointly as electron transfer layer 3) increase one deck 8-hydroxyl-5-nitroquinoline aluminium film on the film, constitute electron transfer layer jointly, the thickness of 8-hydroxyl-5-nitroquinoline aluminium film is generally 1-10nm in this case, preferred 2-5nm.
For improving the electronics injection efficiency of device, improve luminous efficiency, above-mentioned device also can comprise an electron injecting layer between electron transfer layer and negative electrode, be generally one deck LiF film, thickness is generally 0.5nm.
Above-mentioned hole transmission layer material therefor can be N, N '-two-(3-naphthyl)-N, N '-phenylbenzene-[1,1 '-phenylbenzene]-4,4 '-diamines (N, N '-diphenyl-N, N '-bis (1,1 '-biphenyl)-4,4 '-diamine, NPB), this is one of organic hole transport material the most frequently used in the present organic electroluminescence device.
Oxine aluminium (tris (8-hydroxy)-quinoline-aluminium, Alq 3) be one of at present the most frequently used luminescent material, the still electron transport material of generally acknowledging can be used as luminescent layer or the luminescent layer electron transfer layer of holding concurrently in device.
The material of above-mentioned negative electrode can be selected aluminium, magnesium silver alloys, lithium-aluminium alloy or calloy etc.
The preparation of above-mentioned organic electroluminescence device may further comprise the steps:
1, evaporation or solution spin coating hole transmission layer on anode;
2, evaporation or solution spin coating luminescent layer on hole transmission layer;
3, on luminescent layer evaporation or solution spin coating organic electronic transport material as electron transfer layer;
4, direct evaporation negative electrode on electron transfer layer, perhaps first evaporation electron injecting layer, evaporation negative electrode again.
Organic layer in the device all adopts vacuum evaporation making or solution spin coating to make, and its method is well known to those skilled in the art, repeats no more in this.
Electron transport material 8-hydroxyl of the present invention-5-nitroquinoline aluminium is because the existence of strong electron-withdrawing group group nitro has the Alq of ratio 3Stronger electron transport property, and its lumo energy is between Alq 3And between the LiF/Al, can make the transmission balance more of the two kinds of current carriers (electronics and hole) in the device as buffer layer, improve the light extraction efficiency of device.Experiment shows, adds 8-hydroxyl-5-nitroquinoline aluminium and can better transport electronics as the device of electron transfer layer, and the bright voltage that opens of device obviously reduces, and device is significantly improved at the luminosity of low-voltage area (3-8.5V).
Description of drawings
Fig. 1 a is the structural representation of the device 2a among the embodiment two; Fig. 1 b is the structural representation of the device 2b among the embodiment two.
Fig. 2 is device 2a among the embodiment two and the current-voltage curve of 2b.
Fig. 3 a is the structural representation of the device 3a among the embodiment three; Fig. 3 b is the structural representation of the device 3b among the embodiment three.
Fig. 4 is device 3a among the embodiment three and current density-voltage pattern of 3b.
Fig. 5 is device 3a among the embodiment three and brightness-voltage pattern of 3b.
Embodiment
Below in conjunction with accompanying drawing, describe the present invention in detail by embodiment, but be construed as limiting the invention never in any form.
Synthesizing of embodiment one, 8-hydroxyl-5-nitroquinoline aluminium
Dispose 8-hydroxyl-5-nitroquinoline and AlCl respectively 3The dehydrated alcohol saturated solution (dissolving 1 gram 8-hydroxyl-5-nitroquinoline needs 450 milliliters of dehydrated alcohols approximately, dissolving 1 gram AlCl 3Need 25 milliliters of dehydrated alcohols approximately), press AlCl then 3: 8-hydroxyl-5-nitroquinoline mol ratio 1: 3 is with AlCl 3Solution dropwise joins in 8-hydroxyl-5-nitroquinoline solution, at room temperature stirs 8-10 hour after-filtration.After the gained solid carried out vacuum-sublimation and purify, promptly obtain purified 8-hydroxyl-5-nitroquinoline aluminium.
Figure B2009100839097D0000041
The measurement of embodiment two, electronic transmission performance
With electron transport material Alq commonly used 3As reference, adopt Al/LiF to do electrode, preparation has only electronics to characterize the electron transport ability of organic materials as the device of current carrier.
Device 2a (reference device)
Adopt Al/LiF to do electrode, preparation has only electronics to characterize Alq as the device of current carrier 3Electron transport ability.The structure of device 2a as shown in Figure 1a, on anode ITO be successively Al (50nm),
Figure B2009100839097D0000042
Alq 3(40nm),
Figure B2009100839097D0000043
With negative electrode Al (110nm), the device preparation process is as follows:
(1) clean ITO: ultrasonic cleaning 10 minutes in deionized water, acetone, ethanol respectively, in the plasma clean instrument, handled 1 minute then;
(2) vacuum evaporation Al on anode ITO, thickness
Figure B2009100839097D0000044
(3) vacuum evaporation LiF on Al, speed
Figure B2009100839097D0000045
Thickness
Figure B2009100839097D0000046
(4) vacuum evaporation Alq on LiF 3, speed
Figure B2009100839097D0000047
Thickness
Figure B2009100839097D0000048
(5) at Alq 3Last vacuum evaporation LiF, speed
Figure B2009100839097D0000049
Thickness
Figure B2009100839097D00000410
(6) vacuum evaporation Al on LiF, speed
Figure B2009100839097D00000411
Thickness
Figure B2009100839097D00000412
Device 2b
Adopt Al/LiF to do electrode, preparation has only electronics to characterize the electron transport ability of 8-hydroxyl-5-nitroquinoline aluminium as the device of current carrier.The structure of device 2b shown in Fig. 1 b, on anode ITO be successively Al (50nm), 8-hydroxyl-5-nitroquinoline aluminium (40nm),
Figure B2009100839097D0000052
With negative electrode Al (110nm), the device preparation process is as follows:
(1) clean ITO: ultrasonic cleaning 10 minutes in deionized water, acetone, ethanol respectively, in the plasma clean instrument, handled 1 minute then;
(2) vacuum evaporation Al on anode ITO, thickness
(3) vacuum evaporation LiF on Al, speed Thickness
Figure B2009100839097D0000055
(4) vacuum evaporation 8-hydroxyl-5-nitroquinoline aluminium on LiF, speed
Figure B2009100839097D0000056
Thickness
Figure B2009100839097D0000057
(5) vacuum evaporation LiF on 8-hydroxyl-5-nitroquinoline aluminium, speed
Figure B2009100839097D0000058
Thickness
Figure B2009100839097D0000059
(6) vacuum evaporation Al on LiF, speed
Figure B2009100839097D00000510
Thickness
Figure B2009100839097D00000511
Measuring result
With the current-voltage curve of current-voltage instrument measuring element 2a and 2b, as shown in Figure 2.Under the situation of having only electronics as current carrier, 8-hydroxyl-5-nitroquinoline aluminum ratio Alq 3Have better transport property, promptly the electron transport ability of 8-hydroxyl-5-nitroquinoline aluminium is better than Alq 3
The measurement of embodiment three, OLED device performance
On the OLED of classics green device basis, verify of the improvement of electron transport material 8-hydroxyl of the present invention-5-nitroquinoline aluminium to device performance.
Device 3a (reference device)
Device 3a is the OLED green device of classical material, with Alq 3As luminescent material, structure is hole transmission layer NPB (50nm), luminous double electron transfer layer Alq on anode ITO shown in Fig. 3 a successively 3(60nm), electron injecting layer
Figure B2009100839097D00000512
With negative electrode Al (110nm).The preparation process of device 3a is as follows:
(1) clean ITO: ultrasonic cleaning 10 minutes in deionized water, acetone, ethanol respectively, in the plasma clean instrument, handled 1 minute then;
(2) vacuum evaporation hole transmission layer NPB on anode ITO, speed Thickness
Figure B2009100839097D00000514
(3) the luminous double electron transfer layer Alq of vacuum evaporation on hole transmission layer NPB 3, speed
Figure B2009100839097D00000515
Thickness
Figure B2009100839097D00000516
(4) at electron transfer layer Alq 3Last vacuum evaporation LiF, thickness
Figure B2009100839097D00000517
(5) vacuum evaporation negative electrode Al on LiF, thickness
Figure B2009100839097D00000518
Device 3b
Device 3b is on the OLED of classical material green device basis, and hydroxyl-5-nitroquinoline aluminium is as electron transfer layer to increase 8-, and structure is hole transmission layer NPB (50nm), luminous double electron transfer layer Alq on anode ITO shown in Fig. 3 b successively 3(60nm), electron transfer layer 8-hydroxyl-5-nitroquinoline aluminium (3nm), electron injecting layer LiF
Figure B2009100839097D0000061
With negative electrode Al (110nm).The preparation process of device 3b is as follows:
(1) clean ITO: ultrasonic cleaning 10 minutes in deionized water, acetone, ethanol respectively, in the plasma clean instrument, handled 1 minute then;
(2) vacuum evaporation hole transmission layer NPB on anode ITO, speed
Figure B2009100839097D0000062
Thickness
Figure B2009100839097D0000063
(3) the luminous double electron transfer layer Alq of vacuum evaporation on hole transmission layer NPB 3, speed
Figure B2009100839097D0000064
About, thickness
Figure B2009100839097D0000065
(3) at Alq 3Last vacuum evaporation electron transfer layer 8-hydroxyl-5-nitroquinoline aluminium, thickness
Figure B2009100839097D0000066
(4) vacuum evaporation LiF on 8-hydroxyl-5-nitroquinoline aluminium, thickness
(5) vacuum evaporation negative electrode Al on LiF, thickness
Measuring result
The current-voltage of device 3a and 3b is measured by the current-voltage instrument, and measuring result is seen Fig. 4; Brightness is measured by Photo ResearchPR-650 spectrophotometer, and measuring result is seen Fig. 5.As can be seen, have 8-hydroxyl-5-nitroquinoline aluminium to be better than the reference device at low-voltage area (3.5V-8.5V), and its current density is also than reference device height as the device brightness of electron transfer layer.The reason that produces this phenomenon has:
1, the existence of strong electron-withdrawing group group nitro makes 8-hydroxyl-5-nitroquinoline aluminium have the Alq of ratio 3Stronger electron transport property makes more electronics to enter the luminous zone from negative electrode and participates in luminous;
2, the lumo energy of 8-hydroxyl-5-nitroquinoline aluminium is between Alq 3And between the LiF/Al, the transmission that can make the two kinds of current carriers (electronics and hole) in the device as buffer layer is balance more, improves the light extraction efficiency of device.
More than described 8-hydroxyl provided by the present invention-5-nitroquinoline aluminium by specific embodiment and in organic electroluminescence device, improve electronics and inject application with transmission and preparation method thereof, those skilled in the art is to be understood that, in the scope that does not break away from essence of the present invention, can make certain deformation or modification to device architecture of the present invention, its preparation method also is not limited to disclosed content among the embodiment.

Claims (10)

1.8-hydroxyl-5-nitroquinoline aluminium is as the purposes of electron transport material.
2. an organic electroluminescence device comprises anode, hole transmission layer, luminescent layer and negative electrode, it is characterized in that, comprises also that between luminescent layer and negative electrode with 8-hydroxyl-5-nitroquinoline aluminium be the electron transfer layer of material.
3. organic electroluminescence device as claimed in claim 2 is characterized in that, 8-hydroxyl-5-nitroquinoline aluminium separately as electron transfer layer or with other materials jointly as electron transfer layer.
4. organic electroluminescence device as claimed in claim 3 is characterized in that, 8-hydroxyl-5-nitroquinoline aluminium is separately as electron transfer layer, and its thickness is 10-50nm.
5. organic electroluminescence device as claimed in claim 3, it is characterized in that, the electron transfer layer of this device is made of jointly the film of 8-hydroxyl-5-nitroquinoline aluminium film and other organic electronic transport materials, and wherein the thickness of 8-hydroxyl-5-nitroquinoline aluminium film is 1-10nm.
6. organic electroluminescence device as claimed in claim 2 is characterized in that, this device also comprises an electron injecting layer between electron transfer layer and negative electrode.
7. organic electroluminescence device as claimed in claim 6 is characterized in that, described electron injecting layer is the LiF film.
8. organic electroluminescence device as claimed in claim 2 is characterized in that, the material of described hole transmission layer is N, N '-two-(3-naphthyl)-N, and N '-phenylbenzene-[1,1 '-phenylbenzene]-4,4 '-diamines.
9. organic electroluminescence device as claimed in claim 2 is characterized in that, the material of described luminescent layer is an oxine aluminium.
10. organic electroluminescence device as claimed in claim 2 is characterized in that, the material of described negative electrode is aluminium, magnesium silver alloys, lithium-aluminium alloy or calloy.
CN2009100839097A 2009-05-12 2009-05-12 Electron transport material and organic electroluminescence device thereof Pending CN101885704A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103824945A (en) * 2012-11-19 2014-05-28 海洋王照明科技股份有限公司 Solar cell device and preparation method thereof
CN105449114A (en) * 2014-08-28 2016-03-30 吉林师范大学 Organic light-emitting device using Cs2CO3 doped graphene as electron injection layer
CN106008338A (en) * 2016-06-03 2016-10-12 广东工业大学 Hydrogen bridge bond-containing 8-hydroxyquinoline type silver complex dimer crystal and preparation method thereof
CN107431137A (en) * 2015-03-25 2017-12-01 精工爱普生株式会社 Functional layer formation composition and its manufacture method, the manufacture method of organic EL element, organic el device, electronic equipment

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103824945A (en) * 2012-11-19 2014-05-28 海洋王照明科技股份有限公司 Solar cell device and preparation method thereof
CN105449114A (en) * 2014-08-28 2016-03-30 吉林师范大学 Organic light-emitting device using Cs2CO3 doped graphene as electron injection layer
CN105449114B (en) * 2014-08-28 2018-01-16 吉林师范大学 Cs2CO3Doped graphene is the organic electroluminescence device of electron injecting layer
CN107431137A (en) * 2015-03-25 2017-12-01 精工爱普生株式会社 Functional layer formation composition and its manufacture method, the manufacture method of organic EL element, organic el device, electronic equipment
CN107431137B (en) * 2015-03-25 2020-02-28 精工爱普生株式会社 Composition for forming functional layer, method for producing same, method for producing organic EL element, organic EL device, and electronic apparatus
CN106008338A (en) * 2016-06-03 2016-10-12 广东工业大学 Hydrogen bridge bond-containing 8-hydroxyquinoline type silver complex dimer crystal and preparation method thereof
CN106008338B (en) * 2016-06-03 2019-02-12 广东工业大学 A kind of two polycrystal of 8-hydroxyquinoline class silver complex and preparation method thereof containing hydrogen bridge band

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Open date: 20101117