A wide tunable nanophosphor NaYO${}_2$:Er${}^{3+}$/Yb${}^{3+}$ by modulating power density

To date, it is still a challenging topic to achieve a wide tunable emission from the same sample under the excitation of a single pump source. Herein, a new sort of nanophosphor NaYO${}_2$:Er${}^{3+}$/Yb${}^{3+}$ is prepared and characterized. In particular, the wide tunable range crossing red-yellow-green-white regions can be realized only by modulating the power density of the 980 nm semiconductor laser. The mechanism of emitting white light is discussed, and two formulae for quantitatively defining the fluorescent material's tuning ability are also offered. At the same time, the nanophosphor on hand possesses a high degree of reversibility. The nanophosphor presents comprehensive application prospects in information security, anticounterfeiting, display, and other fields. (© 2021 Wiley‐VCH GmbH)