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.
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