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High Efficiency White Organic Light‐Emitting Devices Incorporating Yellow Phosphorescent Platinum(II) Complex and Composite Blue Host
Author(s) -
Lai ShiuLun,
Tong WaiYip,
Kui Steven C. F.,
Chan MeiYee,
Kwok ChiChung,
Che ChiMing
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201300281
Subject(s) - phosphorescence , materials science , oled , electroluminescence , phosphorescent organic light emitting diode , iridium , platinum , quantum yield , dopant , photoluminescence , optoelectronics , photochemistry , quantum efficiency , exciton , doping , fluorescence , nanotechnology , chemistry , optics , physics , organic chemistry , layer (electronics) , quantum mechanics , catalysis
A new class of charge neutral, strongly luminescent cyclometalated platinum(II) complexes supported by dianionic tetradentate ligand are synthesized. One of these platinum(II) complexes, Y‐Pt , displays a high photoluminescence quantum yield of 86% and electroluminescence efficacy ( η power ) of up to 52 lm W −1 , and is utilized as a yellow phosphorescent dopant in the fabrication of white organic light‐emitting devices (WOLEDs). WOLEDs based on conventional structures with yellow emission from Y‐Pt in combination with blue emission from bis (4,6‐difluorophenyl‐pyridinato‐ N , C 2 ′) (picolinate) iridium(III) (FIrpic) show a total η power of up to 31 lm W −1 . A two‐fold increase in η power by utilizing a modified WOLED structure comprising of a composite blue host is realized. With this modified device structure, the total η power and driving voltage at a luminance of 1000 cd m −2 can be improved to 61 lm W −1 and 7.5 V (i.e., 10 V for control devices). The performance improvement is attributed to an effectively broaden exciton formation‐recombination zone and alleviation of localized exciton accumulation within the FIrpic‐doped composite host for reduced triplet‐triplet annihilation, yielding blue light‐emission with enhanced intensity. The modified device structure can also adopt a higher concentration of Y‐Pt towards its optimal value, leading to WOLEDs with high efficiency.