Hole injection material for organic electroluminescent device

A technology for electroluminescent devices and hole injection materials, which is applied in neutral or alkaline aqueous solutions and weakly acidic fields. Effects of hole transport ability and luminescent properties

Inactive Publication Date: 2008-10-15
PEKING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the acidity of PSS in PEDOT:PSS (PH value is about 3.0) is easy to corrode t

Method used

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  • Hole injection material for organic electroluminescent device
  • Hole injection material for organic electroluminescent device
  • Hole injection material for organic electroluminescent device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] In this example, the effects of PEDOT:PSS acidity and alkalinity on the performance of OLEDs whose hole transport layers are small molecules are studied. In order to obtain PEDOT with different pH:PSS, the present embodiment adopts following method:

[0027]Dilute the commercially available PEDOT:PSS stock solution (produced by Aldrich, PEDOT: 0.14w.t.%, PSS: 2.6w.t.%) at a ratio of 1:5 (volume ratio before and after), and divide the diluted solution into five parts, using NaOH solution as The lye was used to adjust the pH of the above solution to obtain five parts of PEDOT:PSS solutions with pHs of 3.0 (without adding NaOH), 5.4, 7.6, 10.0 and 13.0, respectively.

[0028] The OLED prepared in this example has a structure of ITO / PEDOT:PSS / NPB / Alq 3 / LiF / Al standard OLED, such as Figure 4a shown. The full name of NPB is N,N'-bis-(3-naphthyl)-N,N'-diphenyl-[1,1'-diphenyl]-4,4'-diamine (N,N' -diphenyl-N, N'-bis(1,1'-biphenyl)-4,4'-diamine), Alq 3 The full name is 8-h...

Embodiment 2

[0038] This example studies the effect of PEDOT:PSS acidity and alkalinity on the performance of OLEDs whose hole transport layer is a polymer. The pH of the PEDOT:PSS is 3.0, 7.6 and 13.0 respectively, and its preparation method is the same as in Example 1.

[0039] The structure of the OLED prepared in this embodiment is ITO / PEDOT:PSS / POPDP / LiMeQ / LiF / Al, such as Figure 4b shown. Among them, the full name of POPDP is N-octyl-3,7-thiazine-2,5-furylidene, and the full name of LiMeQ is 2-methyl-8-hydroxyquinolatolithium (2-Methyl-8-hydroxyquinolinolatolithium), Their structures are as image 3 shown.

[0040] The preparation method of above-mentioned OLED is identical with embodiment 1, difference is:

[0041] Step c) Spin-coat POPDP on the PEDOT:PSS hole injection layer as the hole transport layer and light-emitting layer, wherein POPDP is doped with NPB at a ratio of 1:1 to enhance its hole transport ability and reduce the yellow light material POPDP The fluorescence que...

Embodiment 3

[0045] In this example, the effect of PEDOT:PSS with different pH values ​​on the hole injection capability of OLEDs is studied. The pH of the PEDOT:PSS is the same as in Example 1.

[0046] Both the cathode and the anode of the OLED in this embodiment use electrodes with high work function, so that only holes can be injected, and its structure is ITO glass / PEPOT:PSS / gold, such as Figure 4c shown.

[0047] The preparation method of above-mentioned OLED is identical with embodiment 1, difference is:

[0048] Step c) vapor-deposit gold on the PEDOT:PSS hole injection layer as metal cathode and electron blocking layer, the rate is Thickness is At the same time there are no subsequent steps d), e) and f).

[0049] Figure 9 The current density-voltage diagrams of five OLEDs prepared by the above method are given. It can be seen from the figure that the current density of the device prepared by using alkali-modulated PEDOT:PSS is significantly higher than that of the devi...

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Abstract

The invention discloses a cavity injection material for an organic electroluminescent device, belonging to the organic electroluminescent device research and application field. The material of the invention is water solution of weakly acidic, neutral or alkaline PEDOT and PSS; the pH value of the water solution is preferably within the range of between 5.4 and 13, more preferably within the range of between 5.4 and 10.0, further preferably within the range of between 7.6 and 10.0 and optimally 7.6. The cavity injection material for the organic electroluminescent device adopts the method which is different from the prior method in which different organic solvents are selected or alcohol organic compound is mixed in PEDOT:PSS so as to improve the performance of the PEDOT:PSS, adjusts the pH value of the PEDOT:PSS by mixing organic or inorganic alkali in the general PEDOT:PSS water solution so as to improve the cavity transmittability and the luminescent property of OLED, and has good industrial application prospect.

Description

technical field [0001] The invention relates to a hole-injecting material for an organic electroluminescent device (OLED), specifically, the invention relates to a weakly acidic, neutral or alkaline aqueous solution with PEDOT and PSS as main solutes, belonging to organic electroluminescence Research and application fields of light-emitting devices. Background technique [0002] Organic electroluminescence belongs to injection luminescence. The hole carriers injected from the ITO anode and the electrons injected from the metal cathode recombine in the light-emitting layer to form excitons, and the excitons are deactivated to emit photons. In order to increase the transport of hole carriers, a hole injection layer is usually introduced between the ITO and the hole transport layer. The hole injection layer can increase the adhesion between the hole transport layer and the ITO electrode, increase hole injection and balance electron and hole injection. Commonly used hole inje...

Claims

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Application Information

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IPC IPC(8): C08L65/00C08L25/18C08J3/03C08K3/22C09K11/06H05B33/14
Inventor 陈志坚魏凡杰肖立新龚旗煌
Owner PEKING UNIV
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