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Langmuir-Blodgett Film (langmuir-blodgett + film)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Effect of Fullerene on Photocurrent Performance of 6- O -Porphyrin-2,3-di- O -stearoylcellulose Langmuir-Blodgett Films

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 12 2008
Keita Sakakibara
Abstract Thin films consisting of 6- O -porphyrin-2,3-di- O -stearoylcellulose (H2PCS) and fullerene (C60) were fabricated for anodic photocurrent generation systems by the Langmuir-Blodgett (LB) technique. The , -complexation between the porphyrin moiety and C60 in the LB films was investigated by means of the surface pressure (,)-area (A) isotherms, UV-vis, and fluorescence spectroscopy. The photocurrent density generated from the H2PCS,C60 LB monolayer films exhibited an increase with increasing the C60 proportion and reached a maximum at a mixing ratio of 1:2, yielding a quantum yield of 12.5% and an IPCE (incident photon-to-current efficiency) of 0.50% at a bias potential of +100 mV vs. SCE. Furthermore, the LB five-layer films could give rise to the IPCE value of 1.5% at +100 mV without significant decline of the quantum yields, which was due to the function of C60 as an electron carrier to improve the interlayer electron transfer through each layer. These results have demonstrated a promising method for preparing the donor,acceptor systems using cellulose as a scaffold in the LB films. [source]

Temperature dependence of photoluminescence from CdS nanoclusters formed in the matrix of Langmuir-Blodgett film

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006
E. A. Bagaev
Abstract In this paper photoluminescence from CdS nanoclusters formed in the matrix of Langmuir-Blodgett film has been investigated in the temperature range 5-300 K. The photoluminescence spectrum of the nanoclusters at 300 K consists of two bands at 2.9 and 2.1 eV. Temperature dependence of the high-energy band maximum deviates from the dependence of the energy bandgap of bulk CdS. The integrated PL intensity of this band decreases with increasing temperature up to 75 K, grows in a temperature range 150-230 K, and rapidly falls at temperatures higher 230 K. The experimental data have been explained within the framework of a model of recombination of carriers considering carrier transport between CdS nanoclusters. An energy of electron traps and activation energies of nonradiative recombination have been estimated to be about 120, 4 and 100 meV, respectively. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Preparation, characterization, and electrical properties of dual-emissive Langmuir-Blodgett films of some europium-substituted polyoxometalates and a platinum polyyne polymer

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010
Li Liu
Abstract A new series of organometallic/inorganic composite Langmuir-Blodgett (LB) films consisting of a rigid-rod polyplatinyne polymer coordinated with 2,7-bis(buta-1,3-diynyl)-9,9-dihexylfluorene (denoted as PtP) as the ,-conjugated organometallic molecule, an europium-substituted polyoxometalate (POM; POM = Na9EuW10O36, K13[Eu(SiW11O39)2] and K5[Eu(SiW11O39)(H2O)2]) as the inorganic component, and an amphiphilic behenic acid (BA) as the auxiliary film-forming agent were prepared. Structural and photophysical characterization of these LB films were achieved by ,,A isotherms, absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable, well-defined, and well-organized Langmuir and LB films are formed in pure water and POM subphases, and the presence of Eu-based POM in the subphase causes an area expansion. It is proposed that a lamellar layered structure exists for the PtP/BA/POM LB film in which the POM and PtP molecules can lay down with the interfacial planes. Luminescence spectra of the prepared hybrid LB films show that near-white emission spectra can be obtained due to the dual-emissive nature of the mixed PtP/POM blends. These Pt-polyyne-based LB films displayed interesting electric conductivity behavior. Among them, PtP/BA/POM 13-layer films showed a good electrical response, with the tunneling current up to ±100 nA when the voltage was monitored between ,1 and 7 V. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 879,888, 2010 [source]