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Trilayer Polymer OLED Devices for Passive Matrix Applications

IP.com Disclosure Number: IPCOM000035627D
Publication Date: 2005-Jan-27
Document File: 5 page(s) / 102K

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The IP.com Prior Art Database

Related People

Wencheng Su: AUTHOR [+3]

Abstract

A trilayer polymer OLED device has been developed by inserting a cross-linkable hole transporting layer (LUMATION* HT-12, * Trademark of The Dow Chemical Company) between the hole injection layer (HIL) and the light-emitting polymer layer (LEP). By using such a trilayer device structure, the charge balance is improved and there is a substantial enhancement in device efficiency and operating lifetime. Green OLED devices with The Dow Chemical Company LUMATION Green 1300 Series LEP have shown about 2X enhancement in efficiency and about 7X enhancement in lifetime.

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Trilayer Polymer OLED Devices for Passive Matrix Applications

Trilayer Polymer OLED Devices for Passive Matrix Applications

Wencheng Su and Franky So

OSRAM Opto Semiconductors Inc.

San Jose, CA 95134

Abstract

             A trilayer polymer OLED device has been developed by inserting a cross-linkable hole transporting layer (LUMATION* HT-12, * Trademark of The Dow Chemical Company) between the hole injection layer (HIL) and the light-emitting polymer layer (LEP). By using such a trilayer device structure, the charge balance is improved and there is a substantial enhancement in device efficiency and operating lifetime. Green OLED devices with The Dow Chemical Company LUMATION Green 1300 Series LEP have shown about 2X enhancement in efficiency and about 7X enhancement in lifetime.


 In the past, most of the polymer OLED devices were made based on a device structure consisting of a light emitting polymer (LEP) layer, and a hole injection layer (HIL) such as poly(3,4-ethylenedioxythiophene):poly-styrenesulphonic acid (PEDOT:PSS). While the efficiencies of such devices are respectable, the lifetime performance, particularly for passive matrix applications, is still lagging.   Studies have shown that significant charge imbalance usually exists in bilayer polymer OLED devices.

 

To improve device lifetime performance, we have developed a trilayer polymer device by inserting a cross-linkable hole transporting layer (XL-HTL) between the HIL and the LEP.  A typical trilayer device consists of a PEDOT:PSS hole injection layer (HIL), a cross-linkable hole transport interlayer (XL-HTL), and a light-emitting polymer layer (LEP). Since XL-HTL is cross-linkable, the film thickness can be well controlled and intermixing between the XL-HTL and LEP during the LEP coating process can be avoided.

           Figure 1 shows the current efficiency versus current density for a trilayer green device with 30nm (LUMATION* HT-12, * Trademark of The Dow Chemical Company) XL-HTL. The cross-linkable HT-12 and LUMATION Green 1300 Series light-emitting polymer used in these experiments were supplied by The Dow Chemical Company.  The device data for a corresponding bilayer device without the HT-12 XL-HTL are also shown for comparison. It is apparent that the use of XL-HTL enhances device efficiency under both DC and multiplex (MUX) operating conditions. The trilayer green device shows a peak efficiency of about 19 cd/A at 17 mA/cm2, 3200cd/m2, compared to an efficiency of about 10 cd/A for the correspo...