Bright blue luminescent pyrenyl-containing organosilicon compounds with contrasting charge transport functionality — SiPh2(p-C6H4-pyrenyl)(p-C6H4-N-benzimidazolyl) and SiPh2(p-C6H4-pyrenyl)[p-C6H4-NPh(1-naph)]

Abstract

The authors investigated the impact of electron-transport and hole-transport functional groups on the properties and the performance of blue luminescent organosilicon compounds as bifunctional materials in organic light-emitting devices. Two new pyrenyl-containing organosilicon compounds, SiPh2(p-C6H4-pyrenyl)(p-C6H4-N-benzimidazolyl) (1) and SiPh2(p-C6H4-pyrenyl)[p-C6H4-NPh(1-naph)] (2) were synthesized. Both compounds display bright blue luminescence in solution and in the solid state with a high quantum efficiency, but they have contrasting electroluminescent properties. The presence of the benzimidazolyl group in 1 enables it to function as a bifunctional material (blue emitter and electron transporter) in OLEDs. An efficient triple-layer (CuPc/NPB/1) blue OLED (C.I.E. 0.15, 0.14) was fabricated successfully. The presence of the NPh(1-naph) group in 2 enables its use as an effective transparent hole injection material, but not a blue emitter in OLEDs.Key words: organosilicon compounds, synthesis, luminescence, electroluminescence, devices.