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

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 photoluminescence 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.