Self-activated luminescence in AZn4(BO3)3 (A = K, Rb, Cs) and oxygen-defects-related photoluminescence tuning

The discovery of rare-earth free (RE-free) self-activated phosphors is of fundamental importance for the inorganic luminescence materials. Herein, we report the novel RE-free phosphors AZn4(BO3)3 (A ​= ​K, Rb, Cs) with intrinsic green (505 ​nm) or yellow emissions (585 ​nm), respectively, depending on different annealing conditions. The self-activated luminescence is mainly ascribed to the different kinds of oxygen defects, and the green emission peaking at 505 ​nm is attributed to the singly ionized oxygen vacancy (Vo+) and zinc vacancy (VZn), while the yellow emission arises from the doubly ionized oxygen vacancy (Vo++) and interstitial oxygen (Oi). The as-fabricated white light-emitting diodes (WLEDs) by using the green and yellow RE-free phosphors exhibit a high color-rendering index (Ra ​= ​90.4), indicating the potential for solid-state lighting. The controllable synthesis strategy opens a new gate for the exploration of RE-free self-activated phosphors with tunable emission.