Purification of hole transporting material by means of ultrafiltration and ion exchange chromatography

A hole-transporting material and hole-based technology, which is applied in the manufacture of electrical components, electrical solid-state devices, semiconductor/solid-state devices, etc., can solve problems such as the decline in luminous brightness of organic EL devices that have not yet been established, and achieve the purpose of suppressing the decline in luminous brightness and being easy to remove Effect

Inactive Publication Date: 2006-11-29
SEIKO EPSON CORP
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Problems solved by technology

[0007] However, a specific index for the relationship between the decrease in luminance of organic EL devices and the types and amounts of impurities contained in the component materials used has not yet been established.

Method used

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  • Purification of hole transporting material by means of ultrafiltration and ion exchange chromatography

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no. 1 approach

[0127] In order to suppress the decrease in the emission luminance of the organic EL device, the present inventors have conducted intensive investigations on all the layers constituting the organic EL device, and they have paid particular attention to the layer having the function of transporting holes.

[0128] As a result, the present inventors have found that the decrease in luminance of the organic EL device can be effectively reduced by reducing the amount of impurities contained in the layer capable of transporting holes, particularly nonionic impurities having a molecular weight of 5,000 or less (hereinafter, simply called "nonionic impurities") are suppressed by controlling the amount within a predetermined amount, thus completing the present invention. In the specification, this is described as the first embodiment.

[0129] As described above, in addition to the hole transport layer as a layer having a function of transporting holes, the hole injection layer and the ...

no. 2 approach

[0163] In addition to the above, the present inventors have also found that the decrease in the luminance of organic EL devices can be effectively reduced by adding anionic impurities, cationic impurities and nonionic impurities (hereinafter, simply referred to as "nonionic impurities" with a molecular weight of 5,000 or less) ") are suppressed by controlling the amount within a predetermined amount respectively, thus completing the present invention. In the specification, this is described as the second embodiment.

[0164] If the amount of impurities such as nonionic impurities, anionic impurities, and cationic impurities contained in the hole transport layer is large, a reaction occurs between the hole transport material and the impurities, or the hole transport material acts as a trigger due to the nonionic impurities Instead, structural changes (decomposition and the like, for example) occur, resulting in deterioration of the hole transport layer over time. In addition, ...

Embodiment 1A

[0227]

[0228] A 2.0 wt% aqueous solution of poly(3,4-ethylenedioxythiophene / styrenesulfonic acid) solution (which is a hole transport material and manufactured by Bayer Corp. under the product name "Baytron P") was first prepared as the Refined solution.

[0229] In the poly(3,4-ethylenedioxythiophene / styrenesulfonic acid) used, the weight ratio of 3,4-ethylenedioxythiophene to styrenesulfonic acid was 1:2.

[0230] Then, the solution used for purification was diluted 10 times with ultrapure water to prepare a solution.

[0231] Then, the solution thus prepared for purification was passed through an ultrafiltration unit (which is a stirring-type unit, type 8200 manufactured by Millipore Ltd., and its ultrafiltration membrane has a molecular weight cutoff of 3,000) and then it was concentrated until its The amount becomes the same as that of the solution used for purification before being diluted to remove nonionic impurities having a molecular weight cutoff of 3,000 or le...

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Abstract

In an organic EL device, when a voltage is applied across an anode and a cathode, holes are moved in a hole transport layer and electrons are moved in an electron transport layer, and the holes and the electrons are recombined in a light emitting layer. In the light emitting layer, excitons are produced by energy released upon the recombination, and the excitons release energy in the form of fluorescence or phosphorescence or emit light when returning to the ground state. The hole transport layer is formed from a hole transport material, in which the amount of nonionic impurities having a molecular weight of 5,000 or less, or the amounts of anionic impurities, cationic impurities and nonionic impurities having a molecular weight of 5,000 or less is or are adjusted to be small, so that the decrease of light-emission luminance of the organic EL device is suppressed.

Description

technical field [0001] The present invention relates to a hole transport material for a layer capable of transporting holes in an organic electroluminescent device (element), a layer having a function of transporting holes, an organic electroluminescent device, and a method for manufacturing the hole transport material . Background technique [0002] An organic electroluminescent device (hereinafter referred to as "organic EL device") is known. In the structure of an organic EL device, at least one light-emitting organic layer (organic electroluminescence layer) is provided between a cathode and an anode. Such an organic EL device can significantly reduce the voltage to be applied compared with an inorganic EL device. In addition, devices can also be manufactured that can provide various emission colors. [0003] Currently, in order to obtain higher-performance organic EL devices, various studies are actively being conducted to develop and improve materials used and devic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L51/30
Inventor 篠原祐治篠原誉
Owner SEIKO EPSON CORP
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