High brightness and efficiency green light-emitting diodes based on fluorene-containing conjugated polymers and associated blends

Leonidas C. Palilis; Chris I. Wilkinson; David G. Lidzey; Donal D. C. Bradley; Michael Inbasekaran; Weishi W. Wu

doi:10.1117/12.416921

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2 February 2001 High brightness and efficiency green light-emitting diodes based on fluorene-containing conjugated polymers and associated blends

Leonidas C. Palilis, Chris I. Wilkinson, David G. Lidzey, Donal D. C. Bradley, Michael Inbasekaran, Weishi W. Wu

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Proceedings Volume 4105, Organic Light-Emitting Materials and Devices IV; (2001) https://doi.org/10.1117/12.416921
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

We report on the fabrication and properties of single layer green light-emitting diodes (LEDs) based on fluorene- containing conjugated polymers and associated blends. We have used a new green fluorene based conjugated polymer (namely 5BTF8) as the emissive material as well as the host in blends with a guest hole transport triarylamine/fluorene copolymer (namely BFB) to fabricate bright and efficient single layer green polymer light-emitting diodes (PLEDs). An enhancement in both the electroluminescence quantum and power efficiency is seen for the blend. This observation indicates that the hole transport material leads to a significant improvement in hole injection and transport and thus to an improved charge carrier balance factor. A higher brightness and a lower turn on as well as operating voltage are also achieved for the blend. The emission from a green single layer LED with 5BTF8/BFB (4/1) as the emissive layer reaches a maximum brightness of 35000 cd/m² with a maximum external quantum efficiency of 1.3% or 4.2 cd/A and a maximum power efficiency of 2.5 lm/W. Novel small area LEDs were also fabricated using a SiN insulating layer on top of the ITO that allowed much higher brightnesses to be achieved compared to the standard area LEDs due to the reduced heating and therefor to a better thermal management of the device. The emission from a PEDOT/5BTF8 small area LED reached a maximum brightness of 155,000 and 6,500,000 cd/m² in DC and pulsed mode, respectively.

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Leonidas C. Palilis, Chris I. Wilkinson, David G. Lidzey, Donal D. C. Bradley, Michael Inbasekaran, and Weishi W. Wu "High brightness and efficiency green light-emitting diodes based on fluorene-containing conjugated polymers and associated blends", Proc. SPIE 4105, Organic Light-Emitting Materials and Devices IV, (2 February 2001); https://doi.org/10.1117/12.416921

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