Norio Sawatari

Efficient organic light-emitting diodes with phosphorescent platinum complexes containing N∧C∧N-coordinating tridentate ligand

We describe the phosphorescent characteristics of two platinum complexes containing an N∧C∧N-coordinating tridentate ligand: platinum(II) 3,5-di(2-pyridyl)toluene chloride [Pt(dpt)Cl] and a newly synthesized platinum(II) 3,5-di(2-pyridyl)toluene phenoxide [Pt(dpt)(oph)], together with the performance of organic light-emitting diodes (OLEDs) prepared with these complexes as phosphors. Films containing each one of the complexes in a 4,4’-N,N’-dicalbazolylbiphenyl (CBP) host showed highly efficient photoluminescence. The fabricated OLEDs exhibited high efficiencies; the maximum external quantum efficiency of the device with Pt(dpt)(oph) phosphor after correction of angular dependence of emission was found to be 16.5%. The luminance half decay time of the Pt(dpt)(oph) device under a constant-current operation was considerably longer than that of the Pt(dpt)Cl device.

45.3: Tetra‐Substituted Pyrenes: New Class of Blue Emitter for Organic Light‐Emitting Diodes

We have developed a new class of highly-fluorescent blue emitter for organic light-emitting diodes (OLEDs) consisting of tetra-substituted pyrenes. From the analysis of the excited state diagrams of pyrene and its derivatives by molecular orbital calculations, we found that the new tetra-substituted pyrenes are highly fluorescent. OLEDs fabricated using the synthesized tetra-substituted pyrenes as emitters showed high efficiency and good color purity.

A New Flame Retardant 1,2-Polybutadiene Laminate

A flame retardant 1,2-polybutadiene laminate with excellent dielectric properties and high heat resistance has been developed for high density multilayer printed wiring boards. A high molecular weight 1,2-polybutadiene is selected as a base material to provide prepregs with a bnon-tacky property without semi-curing of the resin. A low molecular weight 1,2-polybutadiene is used to control the resin flow property of prepregs. The desirable flame retardation is achieved while maintaining the excellent dielectric and thermal properties of 1,2-polybutadieney using a new halogenated bisphenol methacrylate compound. The 1,2-polybutadiene laminate exhibits a low dielectric constant (¿ = 3.4) and dissipation factor (tan¿=0.004) and a flammability classification of UL94 V-1. Also, it has a solder resistance at 300°C for over 120 s. The 1,2-polybutadiene multilayer printed wiring board shows no occurrence of resin smears and excellent transmission characteristics, and demonstrates high reliability of interconnectionn between plated-through-holes and internal layers against thermal shock.