Dibenzothiophene, dibenzofuran and pyridine substituted tetraphenyl silicon derivatives hosts for green phosphorescent organic light-emitting diodes

Abstract

Abstract We report the application of four novel tetraphenyl silicon derivatives as host materials in phosphorescent organic light-emitting diodes (PHOLEDs). The novel derivatives are; 3-(4-((4-(dibenzo[b,d]thiophen-4-yl)phenyl)diphenylsilyl)- phenyl)pyridine (DBTSiPy3), 4-(4- ((4-(dibenzo[b,d]thiophen-4-yl)phenyl)diphenyl- silyl)phenyl)pyridine (DBTSiPy4), 3-(4-((4-(dibenzo[b,d]furan-4-yl)phenyl)- diphenylsilyl)phenyl)pyridine (DBFSiPy3) and 4-(4-((4-(dibenzo[b,d]furan-4- yl)phenyl)diphenylsilyl)phenyl)pyridine (DBFSiPy4). They were prepared by the introduction dibenzothiophene (DBT)/dibenzofuran (DBF) and pyridine units into bis(4-bromophenyl)diphenylsilane intermediate. The influences of DBT/DBF and the position of nitrogen atom within the pyridine unit (3- vs 4-position) were studied by theoretical calculations and experimental measurements. To evaluate the electroluminescent (EL) performance of these four materials, (2-phenylpyridine) iridium(III) (Ir(ppy)3) based green PHOLEDs were fabricated using the common device structures. DBF substituted materials (DBFSiPy3 and DBFSiPy4) led to efficient green PHOLEDs with notable external quantum efficiencies (EQE) of 22.9% and 21.9% respectively.