Heterogeneous Transparent Ultrathin Films with Tunable-Color Luminescence Based on the Assembly of Photoactive Organic Molecules and Layered Double Hydroxides

摘要

Multicolor luminescent films have great potential for use in optoelectronics, solid-state light-emitting materials, and optical devices. This work describes a systematic investigation of the ordered assembly of two- (blue/green, blue/ orange, red/blue, red/green) and three-color (blue/red/green) light-emitting ultrathin films (UTFs) by using different photofunctional anions @@[bis(N-methylacridinium)@polyvinylsulfonate ion pairs and anionic derivatives of poly(p-phenylene), poly(phenylenevinylene), and poly(thiophene)] and Mg-Al-layered double hydroxide nanosheets as building blocks. The rational combination of luminescent components affords precise control of the emission wavelengths and intensity, and multicolored luminescent UTFs can be precisely tailored covering most of the visible spectral region. The assembly process of the UTFs and their luminescence properties, as monitored by UV-vis absorption and fluorescence spectroscopy, resulted in a gradual change in luminescence color in the selected light-emitting spectral region upon increasing the number of deposition cycles. X-ray diffraction demonstrates that the UTFs are periodic layered structures involving heterogeneous superlattices associated with individual photoactive anion-LDH units. These UTFs also exhibit well-defined multicolor polarized fluorescence with high polarization anisotropy, and the emissive color changes with polarization direction. Therefore, this work provides a way of fabricating heterogeneous UTFs with tunable-color luminescence as well as polarized multicolor emission, which have potential applications in the areas of light displays and optoelectronic devices.