Band Gap Engineering and Relationship with Luminescence in Rare-Earth Elements Doped ZnO: An Overview.

This review is focused upon unique optical properties of rare earth (RE) doped ZnO nanostructures derived by a cost-effective sol-gel method. Doping of RE elements improves the properties of ZnO due to their special electronic structure, small crystal field splitting and partially filled 4f energy level, surrounded by full 5s and 5p orbitals. RE-element-induced defects regulate energy transfer dynamics, which can add superior features in ZnO. The biocompatibility of ZnO along with its special calibre of sustained tuneable features by RE doping makes it an excellent candidate for a highly demanding field, i.e. bio-imaging. Here, five RE elements, Tb, Ce, Gd, Y and Eu, are chosen to comprehensively review alterations in the optical parameters of ZnO by their doping. Band gap tuning and luminous properties of RE doped ZnO nanostructures, as well as their features and applications in diverse sectors, are majorly highlighted. [ABSTRACT FROM AUTHOR]