Enhanced up-conversion luminescence and temperature-sensing of GdVO4:Ln3+ with dual-wavelength excitation

Abstract

There exists a tendency in the research of up-conversion materials to shift the excitation from 980 nm to multiple excitation wavelengths. A series of GdVO₄:Ln³⁺ with similar sizes and irregular prism morphology were successfully prepared by a co-precipitation technique. A wide multi-color emission corresponding to different Ln³⁺ doping was also obtained under single excitation. It is worth pointing out that among all the studied samples, only the emission intensity of GdVO₄:Yb³⁺/Er³⁺ excited at two-wavelengths (980 nm + 1550 nm) simultaneously was enhanced by a factor of 1.87, compared to the sum of emission intensities excited at two single-wavelengths separately. Moreover, to further enhance the up-conversion luminescence intensity, cation ions (Lu³⁺/Y³⁺) and anion ions (PO₄³⁻) were also doped into the host, and the luminous intensity was also improved to a certain extent. A possible mechanism for energy transfer and possible transitions were also suggested and discussed in detail using an energy level diagram. In addition, not only a high record value of S_a (0.0069 K⁻¹) but also a high S_r (1.13% K⁻¹) is achieved for GdVO₄:Yb³⁺/Er³⁺ in the physiological temperature range (273–453 K). Combining a much intensified dual-wavelength up-conversion signal and good temperature-sensing properties, this work can be extended to the surges of other lanthanide ion doped systems pumped by using multiple-wavelength lasers, and can also open new possibilities for up-conversion color displays and anti-counterfeiting applications.