1250873-71-2Relevant academic research and scientific papers
Pure red electrophosphorescence from polymer light-emitting diodes doped with highly emissive bis-cyclometalated iridium(III) complexes
Tsujimoto, Hidetaka,Yagi, Shigeyuki,Asuka, Hotaka,Inui, Yuji,Ikawa, Shigeru,Maeda, Takeshi,Nakazumi, Hiroyuki,Sakurai, Yoshiaki
, p. 1972 - 1978 (2010)
In order to develop highly emissive red phosphorescent materials for OLED application, novel bis-cyclometalated iridium(III) complexes were developed using the 1-(dibenzo[b,d]furan-4-yl)isoquinolinato-N,C3′ (dbfiq) cyclometalating ligand. When 1,3-bis(3,4-dibutoxyphenyl)propane-1,3- dionate (bdbp) is employed as an ancillary ligand, Ir(dbfiq)2(bdbp) 1 exhibits red photoluminescence (PL) at 640 nm with a quantum yield (ΦPL) of 0.61 (in toluene, 298 K). Replacement of bdbp to dipivaloylmethanate (dpm) and acetylacetonate (acac) (Ir(dbfiq)2(dpm) 2 and Ir(dbfiq)2(acac) 3, respectively) does not affect the PL spectrum, but reduces ΦPL to 0.55 and 0.49 for 2 and 3, respectively. Similar tendency is also found in the doped poly(methyl methacrylate) (PMMA) film, and 1 is more emissive (ΦPL = 0.17) than 2 and 3 (ΦPL = 0.08 and 0.06, respectively). Using 1 as a phosphorescent dopant, polymer light-emitting diodes (PLEDs) were fabricated, of which structure was ITO/PEDOT:PSS (40 nm)/PVCz:1:PBD (100 nm)/CsF (1 nm)/Al (250 nm). Pure red electroluminescence (EL) is obtained from the fabricated PLEDs, affording a CIE chromaticity coordinate of (0.68, 0.31). When 0.51 mol% of 1 is incorporated in the PVCz-based emitting layer, the PLED shows maximum luminance of 7270 cd m-2 at 16.5 V, power efficiency of 1.4 lm W -1 at 7.5 V, and external quantum efficiency of 6.4% at 9.0 V. PLEDs with the same structure and components were also fabricated using 2 and 3, and their device characteristics were investigated. In proportion to the PL quantum yields, 1 affords better device performance than 2 and 3. Owing to four butoxy groups introduced to the bdbp ligand, 1 exhibits high solubility in organic solvents such as chloroform and toluene, and thus, is an excellent red phosphorescent dopant for solution-processed OLEDs. A highly emissive red phosphorescent bis-cyclometalated iridium(III) complex, bis[1-(dibenzo[b,d] furan-4-yl)isoquinolinato-N,C3′]iridium(III) [1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate-O,O] 1 was developed. It exhibits red photoluminescence with ΦPL of 0.61 (toluene, 298 K). The electrophosphorescence from the polymer light-emitting diode containing 1 affords a CIE chromaticity coordinate of (0.68, 0.31) shifting to pure red over the NTSC standard.
