High performance organic light-emitting devices (OLEDs) have been investigated by using fluorescent bis (2-methyl-8-quinolinolato)(para-phenyl-phenolato)aluminum(BAlq) as an emissive layer on the performance of multicolor devices consisting of N, N-bis-(1-naphthyl)-N,NdiphenyI-l,l-biphenyI-4,4-diamine (NPB) as hole transport layer. The results show that the performance of heterostructure blue light-emitting device composed of 8-hydroxyquinoline aluminum (Alq3) as an electron transport layer has been dramatically enhanced. In the case of high performance heterostructure devices, the electroluminescent spectra has been perceived to vary strongly with the thickness of the organic layers due to the different recombination region, which indicates that various color devices composed of identical components could be implemented by changing the film thickness of different functional layers.