A novel tetraphenylsilane-phenanthroimidazole hybrid host material for highly efficient blue fluorescent, green and red phosphorescent OLEDsElectronic supplementary information (ESI) available: Photophysical properties of compound PPI under the same conditions. See DOI: 10.1039/c5tc00333d

A novel organosilane compound, bis(4-(1-phenylphenanthro[9,10- d ]imidazol-2-yl)phenyl)diphenylsilane (Si(PPI) 2 ), has been designed and synthesized. It has a high thermal decomposition temperature of 528 °C and is able to form an amorphous glass with a high glass-transition temperature of 178 °C. In addition, it possesses high singlet and triplet energies and displays efficient energy transfer to the selected blue fluorescent and green and red phosphorescent dopants when used as a host material. Electrochemical measurements and single-carrier devices indicate that Si(PPI) 2 is a bipolar transport material, allowing the injection and transport of both electrons and holes. By using (Si(PPI) 2 ) as a host, high-performance fluorescent blue (FB) and phosphorescent green (PG) and red (PR) OLEDs with a uniform and simple device configuration have been achieved. These OLEDs exhibit very high peak external quantum efficiency (EQE) and peak power efficiency (PE), i.e. 6.1% and 8.0 lm W −1 for FB, 19.2% and 51.1 lm W −1 for PG and 12.0% and 15.6 lm W −1 for PR. Moreover, the high-level EQE of 4.0, 19.1 and 10.6% and PE of 3.0, 41.6 and 7.5 lm W −1 can be maintained by FB, PG and PR, respectively, at the practical luminance of 100 cd m −2 . Furthermore, the emission colors of these OLEDs remain almost unchanged within the whole range of driving voltages. Importantly, the blue OLED displays a pure blue emission (CIE: 0.18, 0.17). A novel organosilane compound Si(PPI) 2 with good carrier-transport ability has been used as an efficient host for high-performance fluorescent pure-blue and phosphorescent green/red OLEDs.