Optical spectroscopy studies of K2Bi(PO4) (MoO4):20%Yb3+,Er3+ phosphors for upconversion applications

Abstract

Upconverting (UC) materials can convert low-energy infrared light to higher energy – visible or even ultraviolet light. To achieve this, the proper amount of the trivalent lanthanide ions needs to be incorporated into appropriate inorganic matrices. This investigation aims to assess the optimal Er3+ concentration level to obtain the most efficient upconverting material in the adopted matrix. The Yb3+ − Er3+ pair was chosen due to the well-known energy transfer mechanism between these two lanthanide ions. A series of K2Bi(PO4) (MoO4) samples co-doped with 20% Yb3+ and 0.5–20% Er3+ was synthesized by a solid-state synthesis method to study optical properties. The phase purity was monitored by powder X-ray diffraction (XRD), and morphological characteristics were investigated by scanning electron microscopy (SEM). After determining the structure, an optical spectroscopy study was accomplished by recording photoluminescence excitation and emission spectra, upconversion emission spectra, thermal quenching, and fluorescence lifetime values of co-doped samples. Moreover, the color coordinates and relative (Sr) and absolute (Sa) sensitivities curves were calculated and modulated.