Modulations of High-Quality White Emission and Fluorescence Temperature Sensing in La/Dy/Eu Tri-Doped KNN Transparent-Ferroelectric Ceramics

Achieving high-quality white light and related effective modulation is crucial for the development of solid-state luminescent materials. However, white emission is frequently manipulated through irreversible chemical routes, departing from the actual applications in solid-state lighting devices that require in-situ modulation. In this study, we designed and prepared La3+/Dy3+/Eu3+ tri-doped (K0.5Na0.5)NbO3 transparent-ferroelectric ceramics, which exhibit abundant optical properties and moderate ferroelectricity. For the characteristics of white light, the emission colors could be regulated by adjusting the excitation wavelength. Meanwhile, on the basis of the decrease in photoluminescence intensity due to photochromic (PC) behavior, modulations of white emission and color coordinates were realized. The regulation of optical properties through the physical route (i.e., maneuverable light illumination) is closer to practical application. In addition, the excellent fluorescence temperature sensing properties (a maximum relative sensitivity of 7.81% K-1 obtained at 233 K) and high PC contrast (75.8%) of the ceramics provide guidance for the design of other multifunctional optoelectronic materials and devices.