Polyplatinayne/polyoxometalate composite Langmuir-Blodgett films: Preparation, structural characterization, and potential optoelectronic applications

A new family of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of rigid-rod polyplatinayne polymer ([Pt-T(OMe-Fl)T] _∞ or [Pt-T(F-Fl)T]_∞, where the triplet bonds are abbreviated by T, and fluorene ring by Fl) as the π-conjugated organometallic molecule, polyoxometalate (POM, POM = K₃PMo ₁₂O₄₀, H₃PW₁₂O₄₀, or H₆P₂W₁₈O₆₂) of the Keggin and Dawson structures as the inorganic component, and dimethyldioctadecylammonium bromide (DODA) or a mixture of octadecanoic acid (OA) and docosanoic acid (DA) as the auxiliary film-forming agent were prepared and characterized by π-A isotherms, UV-Vis absorption spectra, photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that steady, even, and ordered Langmuir and LB films are formed in pure water and polyoxometalate subphases. It was shown that the POM molecules are probably embedded inside the polyplatinayne molecules in the LB film structure and they can quench the luminescence of the Pt polyyne. These Pt-polyyne based LB films display interesting electric conductivity behavior. [Pt-T(OMe-Fl)T]_∞/ DODAZHPW₁₂ monolayer film shows a good electrical conductivity, and the tunneling current amounts to ±100 nA when the voltage is set at ±8 V.