Highly bright blue organic light-emitting devices using spirobifluorene-cored conjugated compounds

An efficient and morphologically stable pyrimidine-containing spirobifluorene-cored oligoaryl, 2,7-bis[2-(4-tert-butylphenyl)pyrimidine-5-yl]-9,9^′-spirobifluorene (TBPSF), as an emitter or a host for blue organic light-emitting devices (OLEDs), is reported. The steric hindrance inherent with the molecular structure renders the material a record-high neat-film photoluminescence (PL) quantum yield of 80% as a pure blue emitter (PL peak at 430 nm) of low molecular weight, and a very high glass-transition temperature ${\mathrm{(T}}_g)$ of 195 °C. Blue OLEDs employing this compound as the emitter or the emitting host exhibit unusual endurance for high currents over 5000 mA/cm². When TBPSF is used as a host for perylene in a blue OLED, maximal brightness of ∼80 000 cd/m² had been achieved, representing the highest values reported for blue OLEDs under dc driving.