Synthesis and Photoelectrical Properties of Two Potential Solution-Processed Blue Fluorescent Emitters Based on Fluorene-Arylamine Derivatives End-Capped with Anthracene/Pyrene Molecules

Two novel potential solution-processed blue fluorescent emitters composed of a core fluorenediphenylamine unit capped with either anthracene (FAn) or pyrene (FPy) were synthesized and characterized. They were both soluble in common organic solvents and solutions gave smooth films after spin coating. Their optical properties in solution and in the film were investigated by UV-visible and photoluminescence (PL) spectroscopy. The PL emission maximum of FAn and FPy in the film state were found to be 449 and 465 nm, respectively. The electrochemical properties of the as-prepared samples were studied by cyclic voltammetry. The estimated highest occupied molecular orbital (HOMO) energy levels were -5.37 and -5.36 eV for FAn and FPy, respectively. These results indicate that the introduction of diphenylamine effectively prevents plane stacking of the molecules in the solid state, which suppresses the formation of long-wavelength aggregates, and the high HOMO levels enhance the hole-injection ability of the compounds. The results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicate that the two materials have excellent thermal stability with the glass transition temperature of FAn reaching 207 and the thermal decomposition temperature as high as 439 . The good performance of the fluorescent emitters makes them promising candidates as solution-processed blue organic light-emitting diodes.