Downshifting in Cs2NaBiCl6:Er3+: transforming ultraviolet into near infrared radiation

The outstanding assets of stability and non-toxicity have produced a surge of research interest into lead-free double perovskite halides for photovoltaic and optoelectronic applications. Here we report the near infrared (NIR) downshifting of micron and nanoparticle (NP)-size erbium-doped Cs2NaBiCl6 under ultraviolet excitation. The 1.54 nm emission of Er3+ is obtained by the population of the I-4(13/2) level by an internal Er3+ temperature-dependent cross-relaxation process and also from bismuth energy transfer. The NIR emission can be switched from sharp to broad band by selective excitation. The doped NPs may be dispersed in organic solvents and the emission intensity can be tuned by choice of solvent.

Automated summary

This study reports the near infrared downshifting of erbium-doped Cs2NaBiCl6 particles of micron and nanoparticle sizes under ultraviolet excitation. The emission wavelength can be switched from sharp to broad band by selective excitation, and the emission intensity can be tuned by choice of solvent.