Observation of Mediated Cascade Energy Transfer in Europium- Doped ZnO Nanowalls by 1,10-Phenanthroline

ABSTRACT: Embedding rare earth ions into a host material such as alkali halides, semiconductors, and metal oxides has been extensively studied, with the goal to improve performance in light emitting devices and biomedicine. Here, Europium-embedded ZnO nanowall structures have been achieved by a facile electrochemical deposition method. Upon Eu embedment, the nanowalls were found to become thicker and stacked. X-ray photoemission study revealed that Zn(OH)2 was more dominant than ZnO near the surface and it confirmed that Eu(III) was uniformly distributed in the ZnO−Zn(OH)2 core−shell structure. We also measured the photo-luminescence spectra of as-grown, heat-treated and 1,10-phenanthroline surface-functionalized ZnO nanowalls samples, which led us to propose a unique cascade energy transfer model between ZnO, 1,10-phenanthroline, and Eu3+ ion. Rare earth doped ZnO nanomaterials are recognized a