SrMoO4:Er3+-Yb3+ upconverting phosphor for photonic and forensic applications

• The spindle-like Er3+/Er3+-Yb3+ doped/codoped SrMoO4 phosphors have been synthesized via chemical co-precipitation technique.
• Frequency upconversion and colour tunability studies have been performed by using two NIR laser diode excitations.
• Security ink and finger print detection by using 980 nm laser diode has been demonstrated.

The Er3+-Yb3+ codoped strontium molybdate (SrMoO4) phosphors have been synthesized via chemical co-precipitation method by adding ammonium hydroxide as a base reagent. The phase, crystal structure and formation of spindle-like particles present in the prepared phosphors have been recognized by using the X-ray powder diffraction (XRPD) and Field emission scanning electron microscopy (FE-SEM) techniques. The Fourier transform infrared (FTIR) spectroscopy of the developed phosphors has been analyzed to mark the different functional groups present in synthesized phosphors. The multicolour upconversion emissions observed upon excitation with 980 nm and 808 nm laser diode have been explained on the basis of dopants ions concentration, pump power dependence, energy level structure and decay curve analysis. The colour co-ordinate study confirmed that the codoped phosphor emits non-tunable green colour when excited with the 980 nm laser diode, whereas it shows the colour tunability from yellow to green region upon excitation with the 808 nm laser diode. The applicability of non-tunable green colour emission has been demonstrated in the security ink and latent finger print detection. This shows the utility of the developed phosphors in the photonic and forensic applications.

Simplified energy level diagram of the Er3+/Er3+-Yb3+ doped/codoped system under 980 nm and 808 nm diode laser excitations.Figure optionsDownload as PowerPoint slide