Organic light-emitting diodes using an in situ thermally polymerized hole transporting layer

We have fabricated highly efficient organic light-emitting diodes (LEDS) using in situ thermally polymerized hole transporting materials containing triphenylamine/tetraphenyldiaminobiphenyl as side chains. Double-layer LEDs made with these thermally polymerized polymers as the hole transporting layer and tris(8-hydroxyquinoline) aluminum as the emitting layer showed comparable brightness but lower turn-on voltages and better quantum efficiencies than the device made with the conventional hole transporting molecule, ${\mathrm{N-N}}^{\mathrm{\prime }}{\mathrm{-diphenyl-N,N}}^{\mathrm{\prime }}{\mathrm{-bis(3-methylphenyl)(1,1}}^{\mathrm{\prime }}{\mathrm{-biphenyl)-4,4}}^{\mathrm{\prime }}\mathrm{-diamine}.$