TY - JOUR
T1 - Orange and red organic light-emitting devices employing neutral Ru(II) emitters
T2 - Rational design and prospects for color tuning
AU - Tung, Yung Liang
AU - Chen, Li Shiuan
AU - Chi, Yun
AU - Chou, Pi Tai
AU - Cheng, Yi Ming
AU - Li, Elise Y.
AU - Lee, Gene Hsiang
AU - Shu, Ching Fong
AU - Wu, Fang Iy
AU - Carty, Arthur J.
PY - 2006/8/4
Y1 - 2006/8/4
N2 - A new series of charge-neutral Ru(II) pyridyl and isoquinoline pyrazolate complexes, [Ru(bppz)2(PPh2Me)2] (bbpz: 3-tert-butyl-5-pyridyl pyrazolate) (1), [Ru(fppz)2(PPh 2Me)2] (fppz: 3-trifluoromethyl-5-pyridyl pyrazolate) (2), [Ru(ibpz)2(PPhMe2)2] (ibpz: 3-tert-butyl-5-(1-isoquinolyl) pyrazolate) (3), [Ru(ibpz)2(PPh 2Me)2] (4), [Ru(ifpz)2(PPh2Me) 2] (ifpz: 3-trifluoromethyl-5-(1-isoquinolyl) pyrazolate) (5), [Ru(ibpz)2(dpp=)] (dpp= represents cis-1,2-bis-(diphenylphosphino) ethene) (6), and [Ru(ifpz)2(dpp=)] (7), have been synthesized, and their structural, electrochemical, and photophysical properties have been characterized. A comprehensive time-dependant density functional theory (TDDFT) approach has been used to assign the observed electronic transitions to specific frontier orbital configurations. A multilayer organic light-emitting device (OLED) using 24 wt % of 5 as the dopant emitter in a 4,4′-N,N′- dicarbazolyl-1,1′-biphenyl (CBP) host with 4,4′-bis[N-(1-naphthyl)- N-phenylamino]biphenyl (NPB) as the hole-transport layer exhibits saturated red emission with an external quantum efficiency (EQE) of 5.10%, luminous efficiency of 5.74 cd A-1, and power efficiency of 2.62 lm W-1. The incorporation of a thin layer of poly(styrene sulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) between indium tin oxide (ITO) and NPB gave anoptimized device with an EQE of 7.03%, luminous efficiency of 8.02 cd A-1, and power efficiency of 2.74 lm W-1 at 20 mAcm -2. These values represent a breakthrough in the field of OLEDs using less expensive Ru(II) metal complexes. The nonionic nature of the complexes as well as their high emission quantum efficiencies and short radiative lifetimes are believed to be the key factors enabling this unprecedented achievement. The prospects for color tuning based on Ru(II) complexes are also discussed in light of some theoretical calculations.
AB - A new series of charge-neutral Ru(II) pyridyl and isoquinoline pyrazolate complexes, [Ru(bppz)2(PPh2Me)2] (bbpz: 3-tert-butyl-5-pyridyl pyrazolate) (1), [Ru(fppz)2(PPh 2Me)2] (fppz: 3-trifluoromethyl-5-pyridyl pyrazolate) (2), [Ru(ibpz)2(PPhMe2)2] (ibpz: 3-tert-butyl-5-(1-isoquinolyl) pyrazolate) (3), [Ru(ibpz)2(PPh 2Me)2] (4), [Ru(ifpz)2(PPh2Me) 2] (ifpz: 3-trifluoromethyl-5-(1-isoquinolyl) pyrazolate) (5), [Ru(ibpz)2(dpp=)] (dpp= represents cis-1,2-bis-(diphenylphosphino) ethene) (6), and [Ru(ifpz)2(dpp=)] (7), have been synthesized, and their structural, electrochemical, and photophysical properties have been characterized. A comprehensive time-dependant density functional theory (TDDFT) approach has been used to assign the observed electronic transitions to specific frontier orbital configurations. A multilayer organic light-emitting device (OLED) using 24 wt % of 5 as the dopant emitter in a 4,4′-N,N′- dicarbazolyl-1,1′-biphenyl (CBP) host with 4,4′-bis[N-(1-naphthyl)- N-phenylamino]biphenyl (NPB) as the hole-transport layer exhibits saturated red emission with an external quantum efficiency (EQE) of 5.10%, luminous efficiency of 5.74 cd A-1, and power efficiency of 2.62 lm W-1. The incorporation of a thin layer of poly(styrene sulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) between indium tin oxide (ITO) and NPB gave anoptimized device with an EQE of 7.03%, luminous efficiency of 8.02 cd A-1, and power efficiency of 2.74 lm W-1 at 20 mAcm -2. These values represent a breakthrough in the field of OLEDs using less expensive Ru(II) metal complexes. The nonionic nature of the complexes as well as their high emission quantum efficiencies and short radiative lifetimes are believed to be the key factors enabling this unprecedented achievement. The prospects for color tuning based on Ru(II) complexes are also discussed in light of some theoretical calculations.
UR - http://www.scopus.com/inward/record.url?scp=33747611683&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33747611683&partnerID=8YFLogxK
U2 - 10.1002/adfm.200500901
DO - 10.1002/adfm.200500901
M3 - Article
AN - SCOPUS:33747611683
SN - 1616-301X
VL - 16
SP - 1615
EP - 1626
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 12
ER -