Masaru Kinoshita

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.

39.3: Material and Device Structure Design of Blue Phosphorescent OLEDs for High Efficiency and Enhanced Stability

We developed stable and efficient blue phosphorescent materials for OLEDs on the basis of the evaluation of their stability under UV irradiation. Structures of OLEDs with the above-stated materials were improved with the aid of a method to estimate the site distribution of exciton formation in the emissive layer by doping a small amount of fluorophore in it with varied position. The improved blue phosphorescent OLED exhibited high external quantum efficiency (7.9%) with a half life of 10,000 h on a practical luminance (360 cd/m2).