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 cyclo­metalated N^C^N [N^C^N = 1,3-bis­(<i>N</i>-alkyl­benz­imid­azol-2′-yl)­benzene]­platinum­(II) alkynyl and carb­azolyl complexes has been prepared. The structure of one platinum­(II) carb­azolyl complex has been characterized by X-ray crystallography. The corresponding electro­chemical and photo­physical properties have been explored and analyzed. The N^C^N platinum­(II) complexes displayed rich luminescence in degassed dichloro­methane solution, with their emission profiles dependent on the coordinated alkynyl and carb­azolyl ligands. Their emission energies are correlated to the electronic properties of the alkynyl and carb­azolyl ligands. By varying the electronic properties of the alkynyl and carb­azolyl ligands, emission energies could be fine-tuned to cover a wide range of the visible spectrum, as supported by computational studies. A donor–acceptor platinum­(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 platinum­(II) carb­azolyl 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 platinum­(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 cyclo­metalated N^C^N [N^C^N = 1,3-bis­(<i>N</i>-alkyl­benz­imid­azol-2′-yl)­benzene]­platinum­(II) alkynyl and carb­azolyl complexes has been prepared. The structure of one platinum­(II) carb­azolyl complex has been characterized by X-ray crystallography. The corresponding electro­chemical and photo­physical properties have been explored and analyzed. The N^C^N platinum­(II) complexes displayed rich luminescence in degassed dichloro­methane solution, with their emission profiles dependent on the coordinated alkynyl and carb­azolyl ligands. Their emission energies are correlated to the electronic properties of the alkynyl and carb­azolyl ligands. By varying the electronic properties of the alkynyl and carb­azolyl ligands, emission energies could be fine-tuned to cover a wide range of the visible spectrum, as supported by computational studies. A donor–acceptor platinum­(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 platinum­(II) carb­azolyl 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 platinum­(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 alkynylplatinum­(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 platinum­(II) core, the platinum­(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^–1 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 platinum­(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 alkynylgold­(III) complexes containing various tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine (R-C^∧N^∧C), [Au­(R-C^∧N^∧C)­(CCC₆H₄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^∧N^∧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 alkynylgold­(III) complexes containing various tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine (R-C^∧N^∧C), [Au­(R-C^∧N^∧C)­(CCC₆H₄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^∧N^∧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-π-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_<i>y</i> < 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-π-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_<i>y</i> < 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-π-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_<i>y</i> < 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