Electroluminescence (EL) and photoluminescence (PL) from dual-layer thin films made of poly(3-(2-benzotriazolo) ethylthiophene) (PBET) and Poly (2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) have been investigated. In these devices, MEH-PPV was selected as a hole-transporting material based on the consideration of its electronic structures. The energy level of the highest occupied molecular orbital (HOMO) of MEH-PPV (-5.0 eV) lies between that of ITO (-4.8 eV) and that of PBET (-5.5 eV). We have found that the EL signal was almost exclusively generated within the emitting layer. The efficiency and the turn-on voltage measured from dual-layer device were improved 1.2 x 10(-3) and 2.4 V, respectively.