Structural and optical properties of ZnO and Al-doped ZnO microrods obtained by spray pyrolysis method using different solvents

ZnO and Al-doped ZnO microrods were obtained by spray pyrolysis method using different solvents such as methanol and propanol. The effect of the type of solvent in the starting solution on the structural, morphological and optical properties of the samples was investigated. X-ray diffraction patterns showed that the undoped and Al-doped ZnO microrods exhibited hexagonal crystal structure with a preferred orientation along (0 0 2) direction. Surface morphology of the samples obtained by scanning electron microscopy revealed that undoped and Al-doped ZnO microrods grew as quasi-aligned hexagonal shaped microrods with diameters varying between 0.7 and 1.3 μm irrespective of solvents used. Optical studies indicated that microrods had a low transmittance (≅30%) and the band gap increased from 3.24 to 3.26 eV upon Al doping. Photoluminescence measurements indicated the existence of two emission bands in the spectra: one sharp ultraviolet luminescence at ∼383 nm and one broad visible emission ranging from 420 to 580 nm.