Photochromism in inorganic crystallised compounds

New shades of photochromism – yellow sodalites for the detection of blue light

“…Perhaps the most famous of these is the aforementioned borosilicate glass doped with silver salts from Corning Inc. 4 The color in these glasses arises from the formation of silver nanoparticles, similar to the Ag-doped TiO 2 nanoparticles of Ohko et al 5,6 Tungsten and molybdenum oxides have also been popular inorganic photochromic materials showing a yellow-to-blue color change considered for smart windows. 3,[7][8][9] Other matrices and activators have been developed to bring inorganic photochromic materials up to par with their organic counterparts in terms of reversibility 10,11 and diversity of color range, [12][13][14][15][16][17] though the majority of these contain at least one so-called "endangered" element, whose availability will become uncertain in the near future 18 : for example P, V, Cu, Zn, Sr, Y, Nb, Mo, Ag and W. Photochromic sodalites, sometimes called hackmanites, have been a topic of research for almost a century. Recent developments into their synthetic analogues, some of which also display attractive luminescence properties, have shown that they have potential to be developed for a huge range of possible applications.…”

“…1 The first photochromic materials to be discovered were organic molecules, 2 and due to the versatility of organic chemistry and the low density of organic molecules, these have long since replaced their silver chloride counterparts in commercially available photochromic lenses. 3 However, despite the high tunability of organic photochromic molecules, they are often sensitive to humidity, pH and extreme temperatures. Inorganic photochromic materials, on the other hand, are generally superior in terms of robustness.…”

Preparation and properties of water‐based photochromic polyurethane coatings containing Er(III)‐doped WO3

“…Although organic color‐changing components exhibit quick photo‐response and complete discoloration, 11 their synthesis is tedious, time‐consuming, and costly, 12 limiting their practical use in the coating industry. Therefore, it is of paramount importance to develop inorganic color‐changing components for the preparation of photochromic coating materials 13 . Tungsten trioxide (WO 3 ) is one of the inorganic photochromic materials, which can change color under the action of light.…”

“…Therefore, it is of paramount importance to develop inorganic color-changing components for the preparation of photochromic coating materials. 13 Tungsten trioxide (WO 3 ) is one of the inorganic photochromic materials, which can change color under the action of light. It displays tungsten bronze in the presence of water in the air and changes its color from light yellow to blue under the action of light.…”

The structural origin of the efficient photochromism in natural minerals

“…These include thin film oxides (WO 3 , MoO 3 …) ( 3 , 7 , 8 ) which typically have poorly reversible photochromism ( 3 ), rare-earth doped materials (e.g., Ba 5 (PO 4 ) 3 Cl:Eu 2+ and BaMgSiO 4 :Eu 2+ ) ( 9 ), and other materials reviewed by Badour et al. ( 10 ) For the latter, the photochromism originates from a photo-induced electron transfer from the rare-earth ion to an oxygen vacancy, giving rise to a trapped electron, also called an F-center. It is interesting to note that most ceramic materials (e.g., BaMgSiO 4 and Sr 2 SnO 4 ) can actually show photochromism without rare-earth doping but they often have worse coloring efficiency ( 11 ).…”