Engineering luminescence switching and photochromic performance in tungsten bronze oxides for handwriting display based on variable valence ion strategy

Inorganic luminescence materials with intelligent response to external stimuli have drawn considerable interest owing to their alluring applications. Photochromic (PC) is a reversible process which can be adopted to construct subtle luminescence regulation. However, the PC effect is commonly weak for most inorganic materials. It is still challenging to realize strong luminescence switching and PC effect in general inorganic compounds. To fill this gap, tetragonal tungsten bronze (TTB) oxides with ingenious upconversion (UC) luminescence modulation and prominent PC phenomenon were designed by introducing variable valence ion (Mo 6+ ). Under this decorating, the UC luminescence switching ratio and PC contrast could be increased up to 2 and 4 times, respectively. The real-time information encoding based on PC and UC modulation was realized in TTB wafer, confirming the instant handwriting dual-mode display capacity. It is believed that this work will shed new light on the designing of terminal display devices.