Accelerating Non-Phase-Change Photochromism and Upconversion Modulation in Double Perovskite Ba₂LaNbO₆ via Ag⁺ Doping

Double perovskites (DPs) are the latest addition to inorganic photochromic materials and show enormous potential with their fascinating optoelectronic properties and lead-free environmental friendliness. However, real-time reversible optical modulation combining the excellent optoelectronic properties of DPs and photochromism has various limitations, including how to achieve photochromism and acceleration of the response rate. Herein, we have developed a type of rare-earth-doped Ba₂LaNbO₆: Yb³⁺, Er³⁺, Ag⁺ (BLNO) phosphor, which demonstrates a remarkably fast and obvious photochromic response within 1 s. This work accelerates nearly 2 orders of magnitude of response speed of non-phase-change category photochromism in DP oxides over the previous studies. Furthermore, through experimental characterization, we revealed Ag⁺ effectively increases the two main elements for photochromismdefects and carriers. The mechanism of defect formation energy reduction as well as the creation of new deep traps is also discussed through the theoretical calculation method. Finally, we demonstrate the high-speed dual-mode optical information storage based on BLNO flexible thin film through mask patterning and handwriting.