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Efficiency improvement of fluorescent blue device by molecular orientation of blue dopant
Author(s) -
Ogiwara Toshinari,
Ito Hirokatsu,
Mizuki Yumiko,
Naraoka Ryo,
Funahashi Masakazu,
Kuma Hitoshi
Publication year - 2014
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1002/jsid.214
Subject(s) - dopant , materials science , fluorescence , quantum efficiency , electroluminescence , optoelectronics , spectroscopy , oled , optics , doping , nanotechnology , physics , layer (electronics) , quantum mechanics
The relationship between molecular shape of fluorescent blue dopants (BDs) and degree of molecular orientation was studied. BDs with larger ovality showed higher degree of orientation and higher external quantum efficiency (EQE) over 10% in a fluorescent blue device. Impedance spectroscopy, transient electroluminescence spectroscopy, and optical simulation results highly indicated that such high EQE was originated mainly from the optical effect of horizontal‐aligned BDs. Furthermore, a higher EQE of 11.5% at a current density of 10 mA/cm 2 was successfully achieved by modifying molecular structure of BD.