Smart white lighting and multi-mode optical modulations via photochromism in Dy-doped KNN-based transparent ceramics

Dy3+-doped K0.5Na0.5NbO3-Ba(Sc0.5Nb0.5)O-3 transparent ferroelectric ceramics, a novel smart white-lighting (WL) photochromic (PC) material, were prepared by conventional pressureless sintering. The ceramics exhibit high optical transmittance (similar to 67% at 1800 nm), good photoluminescence (PL) performance, high-quality WL, and moderate electrical properties. Meanwhile, high-contrast modulations of optical transmittance and PL intensity (with the maximal modulating values of 20.5% and 57.4%, respectively) have been realized via PC behavior by alternating the illumination of UV light and thermal stimulus. In particular, the reversible modulations of WL intensity, color coordinates, correlated color temperature, and color purity have been achieved through the PC regulation to the intensity ratio of yellow/blue emission. Definitively, based on the effect of intrinsic defects and extrinsic defects (Ba4+/Sc3-x) on the PL properties, the PC mechanism in KNN-based material has been further complemented. The transparent ceramics should be a promising material in white LEDs and optoelectronic multifunctional devices.