Anomalous power-dependent color tuning of Er upconverting luminescence via 1530 nm excitation

The upconversion color tuning of Lanthanide ions usually requires complex core–shell structures and excitation configurations. This work presents simple Er3+ doped Yttria phosphors capable of color change through the manipulation of 1530 nm excitation intensity. Compared to the reported results of Er3+ color change from green to red with the increase in excitation intensity, the formed color-tunable phosphors show an inverse change of red to green. The color tuning mechanisms are attributed to the competition between the upward absorption and the downward decay at the Er3+ intermediate state. Finally, the potential applications of the formed color-tunable phosphors are demonstrated. This work provides a simple solution for high-performance upconversion color tuning and thus shows wide application prospects.