Sky-Blue Organic LEDs

Sky-Blue Organic LEDs

Author: Andrei Dragan

Many luminophores show the phenomenon of aggregation-caused quenching (ACQ). Here the intensity of emission decreases in the aggregated form, leading to a reduced organic light emitting device (OLED) efficiency. Luminogenic materials, in contrast, demonstrate a photophysical effect known as aggregation-induced emission (AIE). The emission intensity of these materials decreases when they are dissolved in good solvents, but increases in the aggregate/solid form in poor solvents.

Lian Duan, Tsinghua University, Beijing, China, Ziyi Ge, Ningbo Institute of Materials Technology & Engineering, China, and colleagues have developed AIE emitters based on a simple combination of imidazole and tetraphenylethene (examples pictured). The team prepared 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)-phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-di-phenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI) using condensation reactions.

All of the materials exhibit excellent AIE behavior. Sky-blue OLEDs were fabricated using these emitters and showed efficiencies as high as 3.13 %. These results indicate a potential of AIE materials for OLED applications.


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