New sulfur-containing host materials for blue phosphorescent organic light-emitting diodesElectronic supplementary information (ESI) available: DSC and mass spectra data for compounds B2tCz and DB2tCz. See DOI: 10.1039/c2jm34165d

Two novel host materials based on carbazole derivatives were synthesized with benzo[ b ]thiophene (B2tCz) or dibenzothiophene (DB2tCz) for use in evaporation-processed blue phosphorescent organic light-emitting diodes. Both host materials exhibited high glass transition temperatures ( T g = 179 °C for B2tCz and T g = 185 °C for DB2tCz) and triplet energy levels ( E T = 2.84 eV for B2tCz and E T = 2.93 eV for DB2tCz). Multilayer devices fabricated using B2tCz or DB2tCz as hosts for the phosphorescence emitter, iridium( iii )bis[(4,6-di-fluorophenyl)pyridinato- N , C 2′]picolinate (FIrpic), showed maximum current efficiencies of 43.3 and 35.6 cd A −1 , power efficiencies of 34.0 and 29.4 lm W −1 , and external quantum efficiencies of 24.6% and 20.0%, respectively. Two phosphorescent blue host materials with sulfur-containing ring moieties were successfully utilized for use in evaporation-processed organic light-emitting diodes (OLEDs).