Effect of Al doping on the visible photoluminescence of ZnO nanofibers

ZnO nanofibers doped with different Al concentration were fabricated by electrospinning method. The nanofibers annealed at 600 °C showed a polycrystalline hexagonal structure with the diameter of about 150 nm. The grain size of the nanofibers decreased after Al doping. The photoluminescence spectra of all the samples presented two luminescence bands at green and orange ranges. And both bands decreased simultaneously with the Al concentration increasing. The luminescence centers of the green and orange bands could be attributed to oxygen vacancies and excess oxygen, which might reside inside the polycrystalline grains and near the grain boundaries, respectively. And the simultaneous decrease of both luminescence bands in the Al-doped ZnO nanofibers might be due to the inwards penetration of excess oxygen.

Research highlights▶ Al doping in ZnO nanofibers can effectively suppress the intensity of the visible photoluminescence of ZnO. ▶ Different from others’ results, the green and orange luminescence bands decrease simultaneously with Al concentration increasing. ▶ The mechanism of the Al doping on the visible photoluminescence of ZnO nanofibers was discussed and a model was introduced.