Investigation of intrinsic and extrinsic defects effective role on producing intense red emission in ZnO:Eu nanostructures

•Effective role of defects on producing red emission at indirect excitation.•VZn and VO defects have important role on energy transfer.•Mg related defects and Zni defects were responsible for blue emission.•Extrinsic and intrinsic defects mediated energy transfer to sensitize Eu3+ ions.•Decrease of red emission because of diminishing in oxygen vacancy.

Europium doped ZnO nanorads and nanosheets were synthesized by hydrothermal method. Effects of Mg doping, morphology and annealing in oxygen ambient on structural and optical properties of ZnO nanostructures were investigated using X-ray diffraction (XRD), particle size analysis (PSA), thermo gravimetric analysis (TGA), differential thermal analysis (DTA), differential thermo gravimetry (DTG), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). This study recommends that both of intrinsic and extrinsic defects facilitate energy transfer (ET) from the ZnO host to Eu3+ ions and consequently have efficient role on producing intense red emission at indirect excitation. The results also showed that annealing process improved the crystal structure of ZnO nanosheets due to decrease of surface defects; however decreased ET and red emission because of diminishing in oxygen vacancy. In addition in ZnO nanorods sample with more surface area in comparison with ZnO nanosheets sample deep level emissions are enhanced.

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