Premium
Bright and Efficient, Non‐Doped, Phosphorescent Organic Red‐Light‐Emitting Diodes
Author(s) -
Song Y.H.,
Yeh S.J.,
Chen C.T.,
Chi Y.,
Liu C.S.,
Yu J.K.,
Hu Y.H.,
Chou P.T.,
Peng S.M.,
Lee G.H.
Publication year - 2004
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.200400137
Subject(s) - phosphorescence , materials science , doping , oled , phosphorescent organic light emitting diode , diode , optoelectronics , red light , nanotechnology , optics , fluorescence , physics , layer (electronics) , botany , biology
Abstract Ir (III) metal complexes with formula [(nazo) 2 Ir(Fppz)] ( 1 ), [(nazo) 2 Ir(Bppz)] ( 2 ), and [(nazo) 2 Ir(Fptz)] ( 3 ) [(nazo)H = 4‐phenyl quinazoline, (Fppz)H = 3‐trifluoromethyl‐5‐(2‐pyridyl) pyrazole, (Bppz)H = 3‐ t ‐butyl‐5‐(2‐pyridyl) pyrazole, and (Fptz)H = 3‐trifluoromethyl‐5‐(2‐pyridyl) triazole] were synthesized, among which the exact configuration of 1 was confirmed using single‐crystal X‐ray diffraction analysis. These complexes exhibited bright red phosphorescence with relatively short lifetimes of 0.4–1.05 μs in both solution and the solid‐state at room temperature. Non‐doped organic light‐emitting diodes (OLEDs) were fabricated using complexes 1 and 2 in the absence of a host matrix. Saturated red electroluminescence was observed at λ max = 626 nm (host‐emitter complex 1 ) and 652 nm (host‐emitter complex 2 ), which corresponds to coordinates (0.66,0.34) and (0.69,0.31), respectively, on the 1931 Commission Internationale de l'Eclairage (CIE) chromaticity diagram. The non‐doped devices employing complex 1 showed electroluminance as high as 5780 cd m –2 , an external quantum efficiency of 5.5 % at 8 V, and a current density of 20 mA cm –2 . The short phosphorescence lifetime of 1 in the solid state, coupled with its modest π–π stacking interactions, appear to be the determining factors for its unusual success as a non‐doped host‐emitter.