An electrochemically deposited composite film of poly(3-substituted thiophen) and insulating nitrile butadiene rubber (NBR) was used as the emission layer of a polymer electroluminescence (EL) device. The composite film on an ITO substrate was uniform, and by using this film current leakage was prevented. The device with the composite film as the EL emission layer shows rectification properties, the emitted color depending on the substituent of thiophen units. By coating with NBR after the electrodeposition of a poly(3-substituted thiophen) film, EL characteristics were improved compared with the device with NBR coating performed before electropolymerization. Moreover, by using electropolymerized poly(3-n-octylthiophen) film as a hole transporting layer, the luminance of an organic EL device with a poly(N-vinylcarbazole) dip-coating layer was remarkably enhanced. The addition of the hole transporting layer reduced the turn-on bias voltage and increased the emission intensity to 700 cd m-2.
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