Near-Infrared Absorption and Polarized Luminescent Ultrathin Films Based on Sulfonated Cyanines and Layered Double Hydroxide

Abstract

Organic−inorganic hybrid ultrathin films (UTFs) were fabricated by alternate assembly of sulfonated carbocyanine derivate (Scy) and exfoliated Mg−Al-layered double hydroxide (LDH) monolayers via layer-by-layer (LbL) method, which show uniform near-infrared (NIR) absorption and photoluminescence properties. UV−vis absorption and fluorescence spectroscopy indicate a stepwise and regular growth of the UTFs upon increasing deposition cycles. X-ray diffraction demonstrates that the UTFs possess periodical layered structure with the basal spacing of 3.3 nm; scanning electron microscopy and atomic force microscopy show that the UTFs surface are microscopically smooth and uniform. The Scy/LDH UTFs exhibit well-defined polarized photoemission character with the maximum luminescence anisotropy as high as ∼0.8. Moreover, the Scy/LDH UTFs display higher stability than the pristine Scy, suggesting that the existence of LDH nanosheets enhance the thermal performance of the Scy dye. A molecular dynamics study was carrie...