Layered MPS3 (M = Mn, Cd) thin films as host matrixes for nonlinear optical material processing

The possibility of processing MPS3 (M = Mn, Cd) layered materials as thin films capable of intercalating nonlinear optical chomophores is investigated. Two different synthetic routes are presented. The first method (solution approach) involves the coprecipitation of transition-metal ions Mn2+ with ligands (P2S64-) followed by casting on a glass substrate. Such films have a composition similar to the high-temperature-synthesized MnPS3 phase but exhibit a much lower crystallinity. However, XRD patterns reveal a preferential orientation of the layers parallel to the support. The second process (solid-state approach) uses the ability of the MPS3 layered compounds to be exfoliated through the successive intercalations of K+ and Li+ cations. The resulting compounds of formula M1-xPS3Li2x. nH(2)O (x = 0.18 for the manganese derivative and 0.16 for the cadmium derivative) readily form highly orientated thin films. Highly transparent thin films were obtained from the CdPS3 starting material. The lithium intercalate thin films were characterized by thermogravimetric techniques, IR spectroscopy, and X-ray diffraction. Their mechanical stability was found to be slightly better than that of the solution-approach-based thin films. The intercalation of a nonlinear optical chromophore (4-[4-(dimethylamino)-alpha-styryl]-1-methylpyridinium) was performed in these thin layered films, which were found to be much more reactive that the parent bulk MPS3.