Two-mode upconversion color-tuning of Er:NaYbF4 nanocrystals and their high-efficiency photothermal conversion

Er:NaYbF 4 @NaLuF 4 alloyed nanocrystals (24 nm) were synthesized, which achieved dual-mode color-tuning and showed 34% photothermal conversion efficiency. It shows great potential in the fields of anti-counterfeiting and non-invasive cancer treatment.