8 research outputs found
Synthesis and Characterization of Luminescent Cyclometalated Platinum(II) Complexes with Tunable Emissive Colors and Studies of Their Application in Organic Memories and Organic Light-Emitting Devices
A series of luminescent cycloÂmetalated
N^C^N [N^C^N = 1,3-bisÂ(<i>N</i>-alkylÂbenzÂimidÂazol-2′-yl)Âbenzene]ÂplatinumÂ(II)
alkynyl and carbÂazolyl complexes has been prepared. The structure
of one platinumÂ(II) carbÂazolyl complex has been characterized
by X-ray crystallography. The corresponding electroÂchemical
and photoÂphysical properties have been explored and analyzed.
The N^C^N platinumÂ(II) complexes displayed rich luminescence in degassed
dichloroÂmethane solution, with their emission profiles dependent
on the coordinated alkynyl and carbÂazolyl ligands. Their emission
energies are correlated to the electronic properties of the alkynyl
and carbÂazolyl ligands. By varying the electronic properties
of the alkynyl and carbÂazolyl ligands, emission energies could
be fine-tuned to cover a wide range of the visible spectrum, as supported
by computational studies. A donor–acceptor platinumÂ(II) complex
has been utilized to fabricate memory devices that exhibit binary
memory performances with low operating voltages, high ON/​OFF
ratios, and long retention times. Solution-processable OLEDs have
been fabricated based on another platinumÂ(II) carbÂazolyl complex,
resulting in a maximum external quantum efficiency of up to 7.2%,
which is comparable to that of the vacuum-deposited devices based
on the small-molecule counterpart, illustrating the multifunctional
nature of the platinumÂ(II)-containing materials
Synthesis and Characterization of Luminescent Cyclometalated Platinum(II) Complexes with Tunable Emissive Colors and Studies of Their Application in Organic Memories and Organic Light-Emitting Devices
A series of luminescent cycloÂmetalated
N^C^N [N^C^N = 1,3-bisÂ(<i>N</i>-alkylÂbenzÂimidÂazol-2′-yl)Âbenzene]ÂplatinumÂ(II)
alkynyl and carbÂazolyl complexes has been prepared. The structure
of one platinumÂ(II) carbÂazolyl complex has been characterized
by X-ray crystallography. The corresponding electroÂchemical
and photoÂphysical properties have been explored and analyzed.
The N^C^N platinumÂ(II) complexes displayed rich luminescence in degassed
dichloroÂmethane solution, with their emission profiles dependent
on the coordinated alkynyl and carbÂazolyl ligands. Their emission
energies are correlated to the electronic properties of the alkynyl
and carbÂazolyl ligands. By varying the electronic properties
of the alkynyl and carbÂazolyl ligands, emission energies could
be fine-tuned to cover a wide range of the visible spectrum, as supported
by computational studies. A donor–acceptor platinumÂ(II) complex
has been utilized to fabricate memory devices that exhibit binary
memory performances with low operating voltages, high ON/​OFF
ratios, and long retention times. Solution-processable OLEDs have
been fabricated based on another platinumÂ(II) carbÂazolyl complex,
resulting in a maximum external quantum efficiency of up to 7.2%,
which is comparable to that of the vacuum-deposited devices based
on the small-molecule counterpart, illustrating the multifunctional
nature of the platinumÂ(II)-containing materials
Strategy for the Realization of Efficient Solution-Processable Phosphorescent Organic Light-Emitting Devices: Design and Synthesis of Bipolar Alkynylplatinum(II) Complexes
A new class of highly luminescent
bipolar alkynylplatinumÂ(II) complexes
has been synthesized, characterized, and applied as phosphorescent
dopants in the fabrication of solution-processable organic light-emitting
devices (OLEDs). Through the incorporation of a delicate balance of
electron-donating carbazole moieties and electron-accepting phenylbenzimidazole
or oxadiazole moieties into the platinumÂ(II) core, the platinumÂ(II)
complexes have been demonstrated to exhibit bipolar charge transport
character with high photoluminescence quantum yields of up to 0.75
in thin films. The introduction of <i>meta-</i>linkages
into the complexes further helps weaken the donor–acceptor
interactions, facilitating better carrier-transporting abilities.
More importantly, high-performance solution-processable green-emitting
OLEDs with maximum current efficiencies of up to 57.4 cd A<sup>–1</sup> and external quantum efficiencies of up to 16.0% have been realized.
This is among the best performances for solution-processable phosphorescent
OLEDs reported based on platinumÂ(II) complexes as well as bipolar
metal complexes
Functionalized Bis-Cyclometalated Alkynylgold(III) Complexes: Synthesis, Characterization, Electrochemistry, Photophysics, Photochemistry, and Electroluminescence Studies
A series of luminescent
alkynylgoldÂ(III) complexes containing various
tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine
(R-C<sup>∧</sup>N<sup>∧</sup>C), [AuÂ(R-C<sup>∧</sup>N<sup>∧</sup>C)Â(Cî—¼Cî—¸C<sub>6</sub>H<sub>4</sub>î—¸R′)] has been successfully synthesized and characterized.
Complexes <b>1</b> and <b>6</b> have been determined by
X-ray crystallography. Electrochemical studies show a ligand-centered
reduction that originated from the tridentate R-C<sup>∧</sup>N<sup>∧</sup>C pincer ligands and an alkynyl-centered oxidation.
The photophysical properties of the complexes have been studied in
detail by electronic absorption and emission studies. Tunable photoluminescence
behaviors have been observed, with the emission maxima spanning through
the visible region from 476 to 669 nm in dichloromethane at room temperature,
and the complexes were also found to be emissive in various media
at both room and low temperatures. Transient absorption studies have
been conducted to investigate the excited state properties of the
complexes. Furthermore, selected complexes have been incorporated
into the emissive layer (EML) of organic light-emitting devices (OLEDs)
and have demonstrated interesting electroluminescence
Functionalized Bis-Cyclometalated Alkynylgold(III) Complexes: Synthesis, Characterization, Electrochemistry, Photophysics, Photochemistry, and Electroluminescence Studies
A series of luminescent
alkynylgoldÂ(III) complexes containing various
tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine
(R-C<sup>∧</sup>N<sup>∧</sup>C), [AuÂ(R-C<sup>∧</sup>N<sup>∧</sup>C)Â(Cî—¼Cî—¸C<sub>6</sub>H<sub>4</sub>î—¸R′)] has been successfully synthesized and characterized.
Complexes <b>1</b> and <b>6</b> have been determined by
X-ray crystallography. Electrochemical studies show a ligand-centered
reduction that originated from the tridentate R-C<sup>∧</sup>N<sup>∧</sup>C pincer ligands and an alkynyl-centered oxidation.
The photophysical properties of the complexes have been studied in
detail by electronic absorption and emission studies. Tunable photoluminescence
behaviors have been observed, with the emission maxima spanning through
the visible region from 476 to 669 nm in dichloromethane at room temperature,
and the complexes were also found to be emissive in various media
at both room and low temperatures. Transient absorption studies have
been conducted to investigate the excited state properties of the
complexes. Furthermore, selected complexes have been incorporated
into the emissive layer (EML) of organic light-emitting devices (OLEDs)
and have demonstrated interesting electroluminescence
High Efficiency Nondoped Deep-Blue Organic Light Emitting Devices Based on Imidazole-Ï€-triphenylamine Derivatives
High-performance deep-blue emitting phenanthroimidazole
derivatives
with a structure of donor–linker–acceptor were designed
and synthesized. By using different linkers and different linking
positions, four deep-blue emitters were obtained and used as emitters
or bifunctional hole-transporting emitters in OLEDs. Such devices
show low turn-on voltages (as low as 2.8 V), high efficiency (2.63
cd/A, 2.53 lm/W, 3.08%), little efficiency roll-off at high current
densities, and stable deep-blue emissions with CIE<sub><i>y</i></sub> < 0.10. Performances are among the best comparing to recently
reported deep-blue emitting devices with similar structures. The results
suggest that the combination of the phenanthroimidazole and the donor–linker–acceptor
structure can be an important approach for developing high performance
deep-blue emitters in particular for lighting applications
High Efficiency Nondoped Deep-Blue Organic Light Emitting Devices Based on Imidazole-Ï€-triphenylamine Derivatives
High-performance deep-blue emitting phenanthroimidazole
derivatives
with a structure of donor–linker–acceptor were designed
and synthesized. By using different linkers and different linking
positions, four deep-blue emitters were obtained and used as emitters
or bifunctional hole-transporting emitters in OLEDs. Such devices
show low turn-on voltages (as low as 2.8 V), high efficiency (2.63
cd/A, 2.53 lm/W, 3.08%), little efficiency roll-off at high current
densities, and stable deep-blue emissions with CIE<sub><i>y</i></sub> < 0.10. Performances are among the best comparing to recently
reported deep-blue emitting devices with similar structures. The results
suggest that the combination of the phenanthroimidazole and the donor–linker–acceptor
structure can be an important approach for developing high performance
deep-blue emitters in particular for lighting applications
High Efficiency Nondoped Deep-Blue Organic Light Emitting Devices Based on Imidazole-Ï€-triphenylamine Derivatives
High-performance deep-blue emitting phenanthroimidazole
derivatives
with a structure of donor–linker–acceptor were designed
and synthesized. By using different linkers and different linking
positions, four deep-blue emitters were obtained and used as emitters
or bifunctional hole-transporting emitters in OLEDs. Such devices
show low turn-on voltages (as low as 2.8 V), high efficiency (2.63
cd/A, 2.53 lm/W, 3.08%), little efficiency roll-off at high current
densities, and stable deep-blue emissions with CIE<sub><i>y</i></sub> < 0.10. Performances are among the best comparing to recently
reported deep-blue emitting devices with similar structures. The results
suggest that the combination of the phenanthroimidazole and the donor–linker–acceptor
structure can be an important approach for developing high performance
deep-blue emitters in particular for lighting applications