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

We have fabricated highly efficient organic light-emitting diodes (LEDS) us ing in situ thermally polymerized hole transporting materials containing tr iphenylamine/tetraphenyldiaminobiphenyl as side chains. Double-layer LEDs m ade with these thermally polymerized polymers as the hole transporting laye r and tris(8-hydroxyquinoline) aluminum as the emitting layer showed compar able brightness but lower turn-on voltages and better quantum efficiencies than the device made with the conventional hole transporting molecule, N-N' -diphenyl-N,N'-bis(3-methylphenyl)(1,1'-biphenyl)-4,4'-diamine. (C) 2000 Am erican Institute of Physics. [S0003-6951(00)03121-1].