Reversible up- conversion luminescence modulation based on UV- VIS light- controlled photochromism in Er3+doped Sr2SnO4+

Up-conversion phosphors with reversible luminescence modulation in response to external stimuli have great potential for applications in optical memory devices, photoswitches and optical sensing. For the accessibility and the controlling convenience, light stimulation is an optimal method to realize the modulation. Here, we report a novel phosphor Sr2SnO4:Er3+, which shows both up-conversion luminescence and reversible photochromic properties upon introducing Er3+ ions into the Sr2SnO4 host. The up-conversion luminescence can be reversibly modulated by alternating ultraviolet light (270-310 nm) and visible light (440-520 nm) irradiation based on the reversible photochromic reaction. 290 and 460 nm are found to be the most efficient wavelengths to control the photochromic reaction and luminescence modulation. And the photochromic degree and luminescence modulation ratio are dependent on the doped Er3+ ion concentration. Large luminescence decrease (84.9%) and increase ratios (266.0%) are achieved in Sr2SnO4:0.005Er(3+). Furthermore, the mechanisms of photochromism and luminescence modulation are investigated.