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Title: Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter

Abstract

Data from a series of phosphorescent blue organic light emitting devices OLEDs with emissive layers consisting of either CBP:6% Firpic or mCP:6% FIrpic show that the triplet energy of the hole and electron transport layers can have a larger influence on the external quantum efficiency of an operating OLED than the triplet energy of the host material. These results are important and insightful given the commonly held view that host materials for phosphorescent OLEDs must have a triplet energy higher than that of the emitter in order to obtain high external quantum efficiency (EQE). A new host material, 4-(di-ptolylaminophenyl)diphenylphosphine oxide (DHM-A2), which has a triplet energy less than that of FIrpic is also reported. OLEDs fabricated using DHM-A2 show improved performance (lower drive voltage and higher external quantum efficiency) over OLEDs using 4- (diphenylphosphoryl)-N,N-diphenylaniline (HMA1), a high performance ambipolar DHM-A2 analogue with a triplet energy greater than FIrpic. Our results suggest modified design rules for the development of new, high performance host materials., ames, more focus can be placed on molecular structures that provide good charge transport (i.e., ambipolarity for charge balance) and good molecular stability (for long lifetimes). This improved understanding provides additional flexibility in order to generate OLEDsmore » with lower operating voltage and longer lifetime, while still providing high EQE.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1028064
Report Number(s):
PNNL-SA-77928
Journal ID: ISSN 1616-301X; 830403000; TRN: US201121%%709
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Volume: 21; Journal Issue: 17; Journal ID: ISSN 1616-301X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHARGE TRANSPORT; DESIGN; EFFICIENCY; ELECTRONS; FLEXIBILITY; LIFETIME; MOLECULAR STRUCTURE; OXIDES; PERFORMANCE; QUANTUM EFFICIENCY; STABILITY; TRANSPORT; TRIPLETS

Citation Formats

Swensen, James S., Polikarpov, Evgueni, Von Ruden, Amber L., Wang, Liang, Sapochak, Linda S., and Padmaperuma, Asanga B. Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter. United States: N. p., 2011. Web. doi:10.1002/adfm.201100586.
Swensen, James S., Polikarpov, Evgueni, Von Ruden, Amber L., Wang, Liang, Sapochak, Linda S., & Padmaperuma, Asanga B. Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter. United States. doi:10.1002/adfm.201100586.
Swensen, James S., Polikarpov, Evgueni, Von Ruden, Amber L., Wang, Liang, Sapochak, Linda S., and Padmaperuma, Asanga B. Tue . "Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter". United States. doi:10.1002/adfm.201100586.
@article{osti_1028064,
title = {Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter},
author = {Swensen, James S. and Polikarpov, Evgueni and Von Ruden, Amber L. and Wang, Liang and Sapochak, Linda S. and Padmaperuma, Asanga B.},
abstractNote = {Data from a series of phosphorescent blue organic light emitting devices OLEDs with emissive layers consisting of either CBP:6% Firpic or mCP:6% FIrpic show that the triplet energy of the hole and electron transport layers can have a larger influence on the external quantum efficiency of an operating OLED than the triplet energy of the host material. These results are important and insightful given the commonly held view that host materials for phosphorescent OLEDs must have a triplet energy higher than that of the emitter in order to obtain high external quantum efficiency (EQE). A new host material, 4-(di-ptolylaminophenyl)diphenylphosphine oxide (DHM-A2), which has a triplet energy less than that of FIrpic is also reported. OLEDs fabricated using DHM-A2 show improved performance (lower drive voltage and higher external quantum efficiency) over OLEDs using 4- (diphenylphosphoryl)-N,N-diphenylaniline (HMA1), a high performance ambipolar DHM-A2 analogue with a triplet energy greater than FIrpic. Our results suggest modified design rules for the development of new, high performance host materials., ames, more focus can be placed on molecular structures that provide good charge transport (i.e., ambipolarity for charge balance) and good molecular stability (for long lifetimes). This improved understanding provides additional flexibility in order to generate OLEDs with lower operating voltage and longer lifetime, while still providing high EQE.},
doi = {10.1002/adfm.201100586},
journal = {Advanced Functional Materials},
issn = {1616-301X},
number = 17,
volume = 21,
place = {United States},
year = {2011},
month = {3}
}