Tetraaryl pyrenes: Photophysical properties, computational studies, crystal structures, and application in OLEDs

Pyrene was derivatized in positions 1, 3, 6, and 8 to yield a series of nine tetraarylpyrenes for which absorption, emission, emission lifetimes and solvatochromism in solution were determined. The fluorescence quantum yields in thin films and crystalline state, electrochemistry, and quantum-chemical calculations were completed for the series along with the X-ray crystal structure analysis of compounds 1, 2, 4, 5, 7, and 9. Compounds 2, 3, 4 as well as 7 were identified as the most suitable candidates for OLED application. Notably, in an unoptimized single-layer device geometry, these compounds exhibited blue electroluminescence coupled with impressively low turn-on voltages and high maximum luminances such as 2.8 V and 13 542 cd m^-2 at 8.2 V for compound 2, respectively.