Nd3+-doped perovskite nanosheets with NIR luminescence

• We have developed for the first time oxide nanosheets with near-infrared luminescent properties.
• The effects of Nd3+ concentrations as well inter-lamellar on the PL properties are revealed.
• Strong coupling of OH vibration with the Nd3+ energy levels because of the extremely thin nature.

Exfoliation of layered materials into ultrathin nanosheets introduces a new cost-effective and environmentally safe fabrication method for novel nanostructured devices. In the present study, we have developed for the first time inorganic oxide nanosheets with near-infrared (NIR) luminescence properties. KLa1−xNdxNb2O7 (x=0.025, 0.05, 0.1, 0.2, or 0.3) powders obtained by a solid state reaction were exfoliated into single-layer metal oxide nanosheets with approximately 1.7 nm thickness by osmotic swelling with tetrabutylammonium cations, followed by the protonation of KLa1−xNdxNb2O7. We observed strong coupling of high-energy OH vibration with the Nd3+ energy levels upon protonation and exfoliation steps because of the extremely thin nature of oxide nanosheet-layers. Colloidal oxide nanosheets with an optimized Nd-doping concentration yielded detectable NIR luminescence due to 4F3/2–4I11/2 (Nd3+) radiative transitions, which opens possible application of these oxide nanosheets as bioimaging probes and bioanalytical sensors.