Cascade organic electroluminescence device with improved voltage stability

An electroluminescent device and electroluminescent technology, which are applied in electroluminescent light sources, electric light sources, electrical components, etc., can solve the problems of high light transparency, reduce device efficiency, and be difficult to obtain, so as to increase light output and reduce light loss, the effect of uncomplicated device structure

Inactive Publication Date: 2004-05-19
EASTMAN KODAK CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The complex structures in these designs present serious manufacturing problems
High optical transparency in the visible range is difficult to achieve due to the presence of electrodes within the stack (internal electrodes)
This reduces the efficiency of the overall device

Method used

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  • Cascade organic electroluminescence device with improved voltage stability
  • Cascade organic electroluminescence device with improved voltage stability
  • Cascade organic electroluminescence device with improved voltage stability

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0128] Embodiment 1 (conventional OLED-comparative example)

[0129] The preparation of a conventional non-cascaded OLED was as follows: A - 1.1 mm thick glass substrate coated with a transparent ITO conductive layer was cleaned and dried with a commercial glass scrubbing tool. The thickness of ITO is about 42 nm and the sheet resistance of ITO is about 68Ω / square. The ITO surface was subsequently treated with an oxidizing plasma to the condition of the surface as an anode. by mixing CHF in an RF plasma chamber 3 A 1 nm thick layer of CFx was deposited on the clean ITO surface as the HIL. The substrate is then transferred to a vacuum deposition chamber for depositing all other layers on top of the substrate. by approximately 10 -6 The following layers were deposited in the following order by sublimation from a heated boat under a vacuum of Torr:

[0130] (1) HTL, 75nm thick, composed of NPB;

[0131] (2) ETL (also used as emission layer), 60nm thick, composed of Alq;

...

Embodiment 2

[0135] Embodiment 2 (comparative example)

[0136] The cascaded OLEDs were prepared as follows: A ~ 1.1 mm thick glass substrate coated with a transparent ITO conductive layer was cleaned and dried with a commercial scrubbing tool. The thickness of ITO is about 42nm and the surface resistance of ITO is about 68Ω / square. The ITO surface is then treated with an oxidizing plasma to the condition that the surface can serve as an anode. By decomposing CHF in an RF plasma processing chamber 3 gas to deposit a 1-nm-thick layer of CFx as HIL on a clean ITO surface. The substrate is then transferred to a vacuum deposition chamber for depositing all other layers on top of the substrate. by approximately 10 -6 The following layers were deposited in the following order by sublimation from a heated boat under a vacuum of Torr:

[0137] (1) HTL, 90nm thick, composed of NPB;

[0138] (2) ETL (also used as emission layer), 30nm thick, composed of Alq;

[0139] [NPB(90nm) / Alq(30nm), den...

Embodiment 3

[0150] Embodiment 3 (the present invention)

[0151] In addition to the Li-doped Alq layer in the junction unit with F 4 - A tandem OLED was manufactured in the same manner as in Example 2, except that 2 nm thick PbO was arranged between the TCNQ-doped NPB layers.

[0152] The cascaded device structure is denoted as ITO / CFx / EL1 / Alq:Li(30nm) / PbO(2nm) / NPB:F 4 -TCNQ(60nm) / EL2 / Mg:Ag.

[0153] The cascaded OLED requires a 12.6V drive voltage to pass 20mA / cm 2 . Its brightness is 1177cd / m 2 And its luminous efficiency was about 5.9 cd / A, which were twice as high as the luminance and luminous efficiency in Example 1. exist image 3 The relationship between brightness decay and operating time is shown in . After 300 hours of operation, the brightness drops by about 10%. Figure 4 The voltage change versus operating time is shown in . The driving voltage was substantially unchanged after 300 hours of operation due to the insertion of a 2 nm thick PbO semiconductor interfacial ...

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Abstract

A cascaded organic electroluminescent device with connecting units having improved voltage stability is disclosed. The device comprises an anode, a cathode, a plurality of organic electroluminescent units disposed between the anode and the cathode, wherein the organic electroluminescent units comprise at least a hole-transporting layer and an electron-transporting layer, and a connecting unit disposed between each adjacent organic electroluminescent unit, wherein the connecting unit comprises, in sequence, an n-type doped organic layer, an interfacial layer, and a p-type doped organic layer, and wherein the interfacial layer prevents diffusion or reaction between the n-type doped organic layer and the p-type doped organic layer.

Description

technical field [0001] The present invention relates to providing a plurality of organic electroluminescent (EL) units to form a cascaded organic electroluminescent device. Background technique [0002] Although organic electroluminescent devices have been known for over two decades, their performance limitations have prevented many desired applications. In its simplest structure, an organic electroluminescent device consists of an anode for hole injection, a cathode for electron injection, and an organic layer sandwiched between these electrodes to sustain charge recombination that produces light emission. These devices are also commonly referred to as organic light emitting diodes, or OLEDs. Representatives of early OLEDs are US-A-3172862 published by Gurnee et al. on March 9, 1965, US-A-3173050 published by Gurnee on March 9, 1965, Dresner, "Double Injection Electroluminescence in Anthracene", RCA Review, 30, 322-334 (1969) and US-A-3710167, Dresner, 9 January 1973. Th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05B33/10H05B33/14
Inventor 廖良生K·P·克卢贝克D·L·坎福特邓青云
Owner EASTMAN KODAK CO
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