Efficient blue electroluminescence of silylene-bridged 2-(2-naphthyl)indole

We synthesised 12,12-diisopropyl-7-methyl-12H-indololo[3,2-d]-naphtho[1,2-b][1]silole from 1-bromo-2-naphtholvia four steps. The silylene-bridged 2-(2-naphthyl)indole exhibited intense blue photoluminescence in solution and in the solid state. For example, the fluorescence maximum of the powder appeared at 476 nm with a high quantum yield (Φ = 0.70). The organic light-emitting device using the silylene-bridged indole as a light-emitting layer demonstrated a high current efficiency of 3.80 cd A−1 and a power efficiency of 3.64 lm W−1 at 10 mA cm−2 with excellent colour coordinates (0.152, 0.094), while the device fabricated with the blue-emissive indole as a dopant achieved even higher current and power efficiencies of 6.68 cd A−1 and 5.58 lm W−1, respectively, at 10 mA cm−2.