Dual-Emissive Langmuir–Blodgett Films of a 9,9-Bis(4-ethynylphenyl)fluorene Derivative of Gold(I) and Some Europium-Substituted Polyoxometalates: Preparation, Characterization and Photoelectric Properties

A new family of organometallic/inorganic composite Langmuir–Blodgett (LB) films consisting of the rigid-rod dinuclear gold(I) complex coordinated with 9,9-bis(4-ethynylphenyl)fluorene (denoted as Au-DPF) as the π-conjugated organometallic molecule coupled with some europium-substituted polyoxometalates (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component were prepared and characterized by π–A isotherms, UV–vis absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and surface photo-voltage spectroscopy. Luminescence spectra of the prepared hybrid LB films show that the near-white emission spectra can be obtained due to the dual-emissive nature of the mixed Au-DPF/POM blends, and POM can facilitate broad aggregate emission bands. These Au-diyne-based LB films displayed interesting electric conductivity behavior. Among them, Au-DPF/K13[Eu(SiW11O39)2] 13-layer film showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between −1.3 and 1.8 V. The photovoltage response of Au-DPF/EuW22 amounts to 1.5 μV.