Synthesis and Characterization of a Blue Light Emitting Material Base on the Spirobifluorene with High Thermal Stability

In this study, we used Suzuki coupling to synthesize 2,2´,7,7´-tetrapyren-1-yl-9,9´-spirobifluorene (TPSBF), a blue emitter featuring four identical strongly emitting pyrene units linked around a stable spirobifluorene core. This fluorine derivative exhibits a high fluorescence yield, extreme thermal stability under N2 (onset decomposition temperature: >540°C), a high glass transition temperature (ca. 240°C), and a stable deep blue emission in the solid state. The presence of the spiro linkage in the structure of TPSBF reduces its tendency to crystallize and increases its glass transition temperature relative to the behavior of the monomeric units. In addition, the tetrahedral nature of the carbon atom at the spiro center preserves the optical and electrochemical characteristics of the pristine pyrene units. A blue organic light emitting diode system by spin-coating process having the configuration indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (50 nm)/ polyvinylcarbazole:TPSBF (43%) (90 nm)/4,7-diphenyl-1,10-phenanthroline (30 nm)/LiF (1 nm)/Al (200 nm) exhibited a luminance of 4,130 cd/m2 at 12 V, Commission Internationale d'Eclairage coordinates of (0.16, 0.16), and current and power efficiencies of 1.9 cd/A and 0.9 lm/W, respectively, at 23 mA/cm2.