Premium
Optimizing the Charge Balance of Fluorescent Organic Light‐Emitting Devices to Achieve High External Quantum Efficiency Beyond the Conventional Upper Limit
Author(s) -
Pu YongJin,
Nakata Go,
Satoh Fumiya,
Sasabe Hisahiro,
Yokoyama Daisuke,
Kido Junji
Publication year - 2012
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201104403
Subject(s) - quantum efficiency , fluorescence , oled , dopant , optoelectronics , materials science , quantum , balance (ability) , charge (physics) , limit (mathematics) , naphthalene , layer (electronics) , nanotechnology , doping , physics , chemistry , optics , organic chemistry , quantum mechanics , medicine , mathematical analysis , mathematics , physical medicine and rehabilitation
The external quantum efficiencies (EQEs) of fluorescent light emitting devices are drastically improved by optimizing the charge balance. When N , N ′‐di(naphthalene‐1‐yl)‐ N , N ′‐diphenylbenzidine (NPD) is used as a hole‐transporting layer (HTL) and Alq 3 as an electron‐transporting layer (ETL) with the green dopant 2,3,6,7‐tetrahydro‐1,1,7,7‐tetramethyl‐1 H ,5 H ,11 H ‐10‐(2‐benzothiazolyl)quinolizino‐[9,9a,1gh]coumarin (C545T), the EQE is observed to be approximately 3%. However, when the HTL and ETL materials are optimized, a 7.5% external quantum efficiency (EQE) in a green‐emitting device and an 8.2% EQE in a blue‐emitting device are achieved at 100 cd m −2 .