Origin of the red emission in zinc oxide nanophosphors

UV and orange-red light emitting zinc oxide nano-phosphors (ZnO NPr) were synthesised by a combustion method using zinc nitrate and zinc acetate as precursors and urea as a fuel. Hexagonal wurtzite structures of ZnO were synthesised. X-ray photoelectron spectroscopy (XPS) indicated that the O1s peak consist of three components: O1 (ZnO), O2 (deficient oxygen; OH groups) and O3 (adsorbed species) centred at 530.3, 531.2 and 532.6 eV, respectively. A broad orange-red emission from 500 to 850 nm was obtained from the ZnO NPr prepared with the nitrate precursor which may be attributed to different kinds of defects, and a sharp UV band, due to the possible passivation of defects, at 392 nm from ZnO NPr prepared with acetate precursor.