The Effect of Dopant Concentration On the Upconversion Process of NaYF4:Yb3+, Er3+ Nanocrystal

Abstract

Lanthaide doped upconverting materials in the recent times have attracted great attention due to their unique optical properties such as large anti-stokes shift, sharp-band emission, long emission lifetime, superior photo stability and near-infraed excitation. These materials have potential applications in biological imaging, medical diagnosis, color displays, temperature sensing and so on. The dopant concentration of lanthanides ions in photon upconversion nanoparticles (UCNPs) remain one of the key point to enhance the upconversion luminescence intensity and, therefore, their application developments. Here, we have analyzed the effect of Yb3+ dopant concentration on NaYF4:Yb3+, Er3+ nanoparticle for the visible upconversion phenomena by employing two different synthetic route i.e thermal decomposition and coprecipitation. The high doping of the sensitizer Yb3+ will accelerate the population of both green and red emiting energy levels, but cause significant concentration quenching in the green emission and little quenching in red emission. Further, we have tried to do in depth analysis of the crystal sturture using different characterization technique like TEM, FESEM, synchrotron based SXRD and rietveld refinement study for the phase purity. This work offers in-depth insight into the UC mechanism of Yb3+ doped NaYF:Yb3+, Er3+ and engineering of novel luminescent materials with distinguished properties.