A Bifunctional Bulky Thienothiophene Derivative; Synthesis, Electronic-Optical Properties and OLED Applications

Applying thienothiophenes (TT) as a linker, a bulky bifunctional thienothiophene, TT-TPA-TPE3, possessing triphenylamine (TPA) and tetraphenylethylene (TPE) units, was designed, synthesized, and fully characterized. Its optical and electronic properties were explained by UV-Vis spectroscopy, cyclic voltammetry (CV) and Aggregation-Induced Emission (AIE) study. TT-TPA-TPE3 exhibited positive solvatochromism in the range of solvent polarities from DMF to toluene, displaying emissions from yellowish to bluish between 480-525 nm. Utilizing TT-TPA-TPE3 as a hole-transporting layer, its organic light emitting devices (OLEDs) were fabricated and their performances were investigated. The synthesized emitter exhibited green and blue emissions in device applications. A mega Stoke's shift of 114 nm in THF and a large Stoke's shift of 78 nm on ITO were observed. A maximum luminance of 580 cd m(-2) and a turn-on voltage of 7.01 V were obtained, indicating that TT-TPA-TPE3 has a good hole-transporting ability.