Efficient multi-coloured Li-doped ZnO thin films fabricated by spray pyrolysis

Undoped and Li-doped ZnO films with bright visible luminescence have been fabricated by the spray pyrolysis technique at 400 °C. The pyrolytic films exhibit multi-coloured emissions of yellow, green and blue, which can be tuned by varying the Li concentration. Simulation of the cathodoluminescence spectra from the Li-doped films using the Huang-Rhys model reveals the energies of the luminescence centres and their electron-phonon coupling strength. These centres are attributable to either VZn or LiZn acceptor states. This work presents a practical route to fabricate inexpensive multi-coloured light emitting coatings on any substrate.