“…In recent decades, the up-converting luminescent materials based on lanthanide ions attracted much scientific interest due to their outstanding luminescence properties. The up-converting luminescent materials are widely used in a variety of applications, such as solar energy [1,2], anti-counterfeiting pigments [3], temperature sensors [4], fluorescence probes [5], bio-imaging [6], cancer therapeutics [7], etc. Usually, the inorganic up-converting luminescent materials contain at least two incorporated lanthanide ions: one as a sensitizer, typically Yb 3+ , and another as an emitter, such as Er 3+ [8,9], Ho 3+ [10][11][12][13], Tm 3+ [14][15][16], etc.…”