title: Anionic poly(p-phenylenevinylene)/layered double hydroxide ordered ultrathin films with multiple quantum well structure: a combined experimental and theoretical study.
abstract: The sulfonated phenylenevinylene polyanion derivate (APPV) and exfoliated Mg-Al-layered double hydroxide (LDH) monolayers were alternatively assembled into ordered ultrathin films (UTFs) employing a layer-by-layer method, which shows uniform yellow luminescence. UV-vis absorption and fluorescence spectroscopy present a stepwise and regular growth of the UTFs upon increasing deposited cycles. X-ray diffraction, atomic force microscopy, and scanning electron microscopy demonstrate that the UTFs are orderly periodical layered structure with a thickness of 3.3-3.5 nm per bilayer. The APPV/LDH UTFs exhibit well-defined polarized photoemission characteristic with the maximum luminescence anisotropy of approximately 0.3. Moreover, the UTF exhibit longer fluorescence lifetime (3-3.85-fold) and higher photostability than the drop-casting APPV film under UV irradiation, suggesting that the existence of a LDH monolayer enhances the optical performance of the APPV polyanion. A combination study of electrochemistry and periodic density functional theory was used to investigate the electronic structure of the APPV/LDH system, illustrating that the APPV/LDH UTF is a kind of organic-inorganic hybrid multiple quantum well (MQW) structure with a low band energy of 1.7-1.8 eV, where the valence electrons of APPV can be confined into the energy wells formed by the LDH monolayers effectively. Therefore, this work not only gives a feasible method for fabricating a luminescence ultrathin film but also provides a detailed understanding of the geometric and electronic structures of photoactive polyanions confined between the LDH monolayers.
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, PR China.
authors.forename: Dongpeng
authors.initials: D
authors.lastname: Yan
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.forename: Min
authors.initials: M
authors.lastname: Wei
authors.forename: Xinrui
authors.initials: X
authors.lastname: Wang
authors.forename: David G
authors.initials: DG
authors.lastname: Evans
authors.forename: Xue
authors.initials: X
authors.lastname: Duan
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D003198:Computer Simulation; D004338:Drug Combinations; D008276:Magnesium Hydroxide / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D015394:Molecular Structure; D010316:Particle Size; D011145:Polyvinyls / Q000737:chemistry*; D045663:Quantum Dots; D013499:Surface Properties
chemical_list: D000838:Anions; D004338:Drug Combinations; D008567:Membranes, Artificial; D011145:Polyvinyls; C470024:poly(4-phenylenevinylene); C013591:aluminum hydroxide, magnesium hydroxide, drug combination; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide