A paper-based visible light-responsive imaging material

Abstract

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 1HNMR, 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.