Molecular Foundry Seminar
"Materials Design Concepts for Efficient Blue OLEDs:
A joint Theoretical and Experimental Study"
Dr. Asanga B. Padmaperuma,
Energy and Efficiency Division, Pacific Northwest National Laboratory
Tuesday, June 14th at 1:00 pm, Bldg. 67 - 3111
View the Foundry Seminar Schedule
Abstract:
Organic light emitting devices (OLEDs) have great potential for lighting, displays and TVs. One remaining technical challenge for very high efficiency OLEDs for solid-state lighting applications is the blue component. Optimization of not only blue emitters, but also host matrices and transport layers is necessary to achieve efficiency and lifetime targets. Charge balance and exciton confinement are key factors in achieving high quantum efficiency in OLED devices. It is a commonly held view that the host material for a phosphorescent emitter in an organic light emitting device (OLED) must have a triplet energy higher than that of the phosphorescent emitter in order to obtain high quantum efficiencies. We show that a combination of HTL, ETL and host with appropriate energy levels can provide high external quantum efficiency (EQE), even with host triplet energy lower than that of the emitter. Specifically, we report results demonstrating improved OLED performance for a new host material, 4-(di-p-tolylamino)phenyl)diphenylphosphine oxide, with a triplet energy lower than FIrpic. Our results suggest modified design rules for the development of new, high performance host materials. Molecular design strategies, device design and OLED data will be discussed.
About the Speaker
Asanga B. Padmaperuma is a Senior Research Scientist at Pacific Northwest National Laboratory, and the Technical lead of the OLED solid-state lighting program. Dr. Padmaperuma earned a PhD from University of Southern California in 2003 in Organic/Polymeric Materials with a focus on synthesis and photophysical studies of novel light emitting polymers for organic electroluminescence applications. Dr. Padmaperuma joined PNNL as a staff member in April 2006 after a two-year PNNL postdoctoral fellowship under the mentorship of Dr. Linda Sapochak and Dr. Paul Burrows. In the fellowship, he expanded his synthetic capabilities and gained hands-on knowledge in design fabrication and testing of OLEDs under the supervision of Dr. Burrows. He has experience in organic synthesis and also specialized in computational modeling of organic materials, vacuum organic thin film deposition, and design and characterization of OLEDs. He has co-authored several publications and been invited to present his work on materials development for OLED many times.
