A paper-based visible light-responsive imaging material

In this paper, we have developed a paper-based optical imaging material responding to visible light. This material consists of a thioxanthone (TX) derivative with the additional phenyl carbazole chromophore, namely 1-phenyl-11,12a-dihydrothiochromeno (3,2-b) carbazol-13 (5H)-one (TX-PC), and leuco crystal violet (LCV). TX-PC is newly synthesized and characterized by 1 HNMR, FTIR and high-resolution mass spectrometer. As a visible light absorbing Type II photoinitiator, TX-PC has an excellent absorption property in the visible region in the absence of an added co-initiator. In other words, TX-PC degrades into lively free radicals when irradiating under visible light which resulting in a color reaction on LCV . The degree of reaction is characterized by UV–vis spectrophotometer. In this study, this material is used for imaging within visible light because of the high efficiency color reaction. We coat a paper substrate with this TX-PC/LCV solution and cover with a pattern photomask. Under the irradiation of the visible light, color reaction occurs to irradiated area while the rest remains colorless. Thus the two areas are distinguished to obtain a clear image as same as the original version.