Collective modulation of upconversion in Ag-BaTiO3: Yb3+, Er3+ by photonic bandgap and surface plasmon resonance effects

Abstract

A series of Ag-BaTiO3: Yb3+, Er3+ inverse opal structures were synthesized by co-precursor sol-gel method. Under near-infrared excitation, the enhanced upconversion emissions were obtained by the coupling of photonic band gap and surface plasm on resonance effects. The green and red luminescence of Ag-BaTiO3: Yb3+, Er3+ were up to 14.2-fold and 12.8-fold higher than the reference sample, respectively. In addition, a rate equation model has been established based on the energy transfer processes, and a thorough analysis has been conducted to clarify the influence of two effects. By altering the photonic bandgap position, corresponding spontaneous emissions could be inhibited and the efficiency of incident light could be improved. With the introduction of plasmonic structures, the green to red ratio was able to be manipulated by the Purcell factor of radiative decay rate and the additional nonradiative decay channels described by Wnr. This work employs an intriguing strategy for modulating and enhancing upconversion luminescence, which is of great value for potential applications in displays and bio-lables.