Synthesis And Application Of Phosphorescent Manganese(?)Complexes Based On Oxygen Ligands

Organic light-emitting diodes?OLEDs?have extensive applications in the fields of lighting and display.As the core components of OLEDs,luminescent materials have been the focus of research.At present,the luminescent materials in commercial OLEDs are mainly iridium???complexes.Because of their high cost,recent research has been focused on developing low-cost and high-efficiency alternatives of iridium-based luminescent materials.It has been recently found that manganese???complexes exhibit efficient phosphorescence with various emission colors.Because of their efficient photoluminescence,phosphorescent manganese???complexes are possibly used as low-cost and high-efficiency light-emitting materials in OLEDs.The investigation in this dissertation is focused on the preparation,photophysical and electroluminescent properties of phosphorescent manganese???complexes.Ligand[?sulfonylbis?2,1-phenylene??bis?diphenylphosphineoxide?]?2?and[?sulfonylbis?3-?9H-carbazol-9-yl?-6,1-phenyl ene??bis?diphenylphosphineoxide?]?4?were prepared.Ligand 4 exhibits strong fluorescence emission in solid state and solution with positive solvatochromic effect.Compound 5 with more rigid structure was obtained upon the acidation of ligand 4 by HPF₆.It does not show positive solvatochromic property.This implies that the positive solvatochromic property of ligand 4 is ascribed to stronger molecular polarity in the excited state than that in the ground state.Two mononuclear manganese???complexes[Mn?L?₂?X?₂]?L=2,X=ClO₄,6;L=4,X=PF₆,7?of ligands 2 and 4 were synthesized,respectively.Manganese???complexes 6 and 7 display orange emission in solid state.Complex 7 is also phosphorescent in solution with red emission.Photophysical studies indicate that the phosphorescent emission of compounds 6 and 7 arises from d-d electronic transitions in manganese???ions.Two tetranuclear manganese???complexes[(F-Mn₄L₂?P+?]?L=p-tert-butylsulfocalix[4]arene,14;L=sulfocalix[4]arene,15?were synthesized.Single crystal structures of complexes 14 and 15 show that four manganese???centers are bridged by a fluoride ion in ?4-F-bonding mode.A sandwich structure is constructed by this plane combined with two calixarene ligands located up and down the plane.Complexes 14 and 15 show strong phosphorescence with red emission in both solid state and solution,originating from d-d electronic transition in manganese???ion.Since the phosphorescence of complexes 14 and 15 is quenched by dioxygen,they could be served as dioxygen sensors.In order to investgate electroluminescent properties,compound 15 was utilized as light-emitting material to fabricate OLEDs.Taking advantage of the optimized structure ITO/PEDOT:PSS?50 nm?/host material?80%?:15?20%??50 nm?/TPBi?50 nm?/LiF?1 nm?/Al?100 nm?,the peak current efficiency?CE?,power efficiency?PE?,extenal quantum yield?EQE?and brightness are 4.8 cd/A,3.2 lm/W,2.8%and 1130 cd/m²,respectively.