Effect of zinc oxide incorporation on the morphology of tris(8-hydroxyquinoline)aluminum/zinc oxide hybrid nanomaterials

We performed an investigation of amorphous tris(8-hydroxyquinoline)aluminum (Alq3) molecules transferred into α-phase crystalline nanomaterials by incorporating a few weight percentage of crystalline zinc oxide (ZnO) nanoparticles. Various shapes of hybrid Alq3–ZnO nanomaterials were synthesized from a one-step solution method at relatively very low temperature. We examined the effect of temperatures and the amount of incorporated ZnO nanoparticles on the evolution of morphologies of hybrid nanomaterials by using field emission scanning electron microscopy. Photoluminescence (PL) spectra of hybrid nanomaterials containing 15 and 25% of ZnO showed a three and five-fold enhancement in PL intensity, respectively, over the pure Alq3 molecules. We attributed the achievement of higher PL intensity of Alq3–ZnO hybrids to the incorporation of crystalline ZnO nanoparticles. This incorporation allowed for energy transfer from ZnO particles and occurrence of caging effect of ZnO nanoparticles thus avoiding excimer formation between Alq3 molecules in the excited state. A blue-shift in the PL emission of the hybrid nanomaterials resulted, with respect to ZnO content, due to the quantum confinement effect of the ZnO nanoparticles.