A nanosheet phosphor of double-layered perovskite with unusual intrananosheet site activator concentration

Abstract

Layered metal oxide nanosheets have been the most promising class of two-dimensional material in the postgraphene area due to their diversity in composition, structure, and functionality. Devising new exfoliation pathways has been an essential requirement in the fabrication of functional devices employing inorganic nanosheets. Here, we report on the exfoliation of a double-layered perovskite, NaGdMgWO:Eu³⁺ (NGMWO:Eu³⁺), into nanosheets via a proton exchange process and intercalation of ethylamine ions. A colloidal suspension of nanosheets exhibited red emission arising from the ⁵D₀ -> ⁷F, transitions of Eu³⁺ under host mediated excitation and direct excitation of Eu³⁺. The exfoliated nanosheets exhibited intense Eu³⁺ emission compared with the bulk form, largely arising from host-mediated excitation rather than direct Eu³⁺ excitation. The enhanced nanosheet emission is attributed to the increased energy transfer efficiency from the host to Eu³⁺, high surface to volume ratio, and lower dimensionality of nanosheets. H₂O sensing in the synthesized NGMWO:Eu³⁺ nanosheets was demonstrated via PL quenching, which followed a combined static and dynamic quenching mechanism.