Light modulation (vis-NIR region) based on lanthanide complex-functionalized carbon dots

A new kind of carbon dots with an average diameter of approximately 3–5 nm were synthesized using L-lysine. Subsequently, a series of lanthanide complex-functionalized carbon dots were designed and synthesized, denoted as Ln-CDs (Ln = Eu, Sm, Er, Yb, Nd). In addition, by changing the ratio of Eu complexes and carbon dots, four kinds of Eu complex-functionalized carbon dots were also obtained (Eu-CDs-1, Eu-CDs-2, Eu-CDs-3, Eu-CDs-4). The derived nanomaterials were characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fluorescence spectroscopy. Upon visible-light excitation, these lanthanide complex-functionalized carbon dots show multicolor visible (Eu; with red, orange, grey and blue colors, respectively) and near-infrared (Sm, Er, Nd, Yb) luminescence (emission covered from 400 nm to 1700 nm spectral region).