The electroluminescence efficiency of an organic light emitting diode (OLED
) based on poly(3-pentylmethoxythiophene) (P5OMe) is improved by two orders
of magnitude by employing the heterostructure architecture realized with a
thin layer of tris(8-hydroxy)quinoline aluminium (Alq3), which acts as bot
h electron transport and emitting layer. The emission can be tuned from the
red to the green spectral region by varying the applied voltage. An additi
onal emission observed both in photoluminescence and electroluminescence at
the polymer/Alq3 interface is tentatively assigned to exciplex emission. (
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