J. Biteau

Bio: J. Biteau is an academic researcher from École Polytechnique. The author has contributed to research in topics: Photochromism & Optical storage. The author has an hindex of 5, co-authored 6 publications receiving 195 citations.

Photochromism of Spirooxazine-Doped Gels

Abstract: Spirooxazine photochromic dyes were trapped in gel thin films Organically modified doped gels showed normal photochromism The kinetics of the photochromism in these gels was quantified using both Gaussian and simple biexponential models in order to take into account the inhomogeneous distribution of free volume in the gel matrix and to compare the photodynamics with that in organic polymers In organic−inorganic hybrid matrices, a competition was observed between normal and reverse photochromisms because of the presence of two chemical environments for the dye molecules The kinetics of photodegradation for dye-doped gels was deduced from the recording of the excitation/emission spectra during UV light irradiation

Organic-inorganic solids by sol-gel processing: optical applications

Abstract: We have developed pure inorganic and hybrid organic-inorganic solids by sol-gel processing of silicon alkoxides. `Dense' gels are obtained at room temperature, in any desired shape, including thin films, and we are able to trap organic molecules or clusters. Gels can be polished and exhibit optical transmission in the visible range similar to that of high-temperature silica glasses. Concerning `gel-molecule' and `gel-nanocrystal' composites, the diversity of the organofunctional alkoxide precursors allows us to modify the optical properties by changing the nature and the strength of chemical and electronic interactions between the optically active guest system and the solid host matrix.

Remanent photoinduced birefringence in thin photochromic sol–gel films

Abstract: High remanent optical anisotropy in photochromic sol–gel films is shown to be photoinduced by discoloration with linearly polarized visible light. This anisotropy results in a linear dichroism in the visible absorption band and in an important birefringence in the near-infrared transparency region. The kinetics of the whole process are quantitatively well described by a simple analytical model. Intrinsic characteristics of the individual molecule, such as the photochemical quantum yield and the anisotropy of their optical properties, are determined. The potential application of this effect to optical data storage is discussed.

Photochromism of Dithienylethene Derivatives Trapped in Sol-Gel Matrices

Abstract: Solid-state materials containing photochromic dithienylethene derivatives were prepared by the sol-gel process in the form of thin films of a few μm-thick. The effect of substituents (pyridyl or methoxyphenyl) of the optically active molecules on photochromic properties was investigated. Thicknesses and refractive indices either at 633 nm or 785 nm were determined in the colored and in the discolored state by using the Attenuated Total Reflexion method. Sol-gel films containing methoxphenyl substituted molecules show a large refractive index change, Δn=3.10−3 at 785 nm. This variation is important considering the low doping level (0.7 wt%).

Hybrid Gels and Nanoscale Chemistry for Optical Applications

Abstract: A large variety of materials for optical and optoelectronic applications has been developed by trapping active organic molecules and nanocrystals into pure inorganic and hybrid organic- inorganic gels. Concerning optically active molecules, we focus only here on luminescent materials for solid state tunable lasers and light-emitting diodes, and photochromic materials for integrated optics and optical storage. Optical properties can be controlled by changing the nature and the intensity of chemical and steric interactions between the organic system and the solid host matrix. Concerning nanocrystals, we present two approaches for the synthesis of transparent solids based on 1I-VI semiconducting nanoparticles. A first category of materials consists in the dispersion of CdS nanoparticles in sol-gel silica matrices. The luminescence can be controlled by offering an alternative pathway for the recombination of surface trapped carriers. A second group of transparent materials is obtained by considering the CdS nanoparticles not only as the optically active units, but also as the building blocks for the whole solid.

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

Abstract: Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Nonlinear Optical Properties of Porphyrins

Abstract: Porphyrins and phthalocyanines have outstanding chemical and thermal stability. The macrocyclic structure and chemical reactivity of tetrapyrroles offers architectural flexibility and facilitates the tailoring of chemical, physical and optoelectronic parameters. The specific optical properties of the tetrapyrrole macrocycle combined with the synthetic methodologies now available and the already available theoretical and spectroscopic knowledge on their optical behavior make porphyrins a target of choice for this area. They are versatile organic nanomaterials with a rich photochemistry and their excited state properties are easily modulated through conformational design, molecular symmetry, metal complexation, orientation and strength of the molecular dipole moment, size and degree of conjugation of the π-systems, and appropriate donor-acceptor substituents. Here we review the structural chemistry and optical properties of recently synthesized porphyrin derivatives that offer potential for nonlinear optical (NLO) applications and complement existing studies on phthalocyanines. Classes of interest include the classic A4 symmetric tetrapyrroles, while optimized systems include push-pull porphyrins, oligomeric and supramolecular self-assembled systems, films and nanoparticle systems, and highly conjugated porphyrin arrays.

Photochromic organic-inorganic hybrid materials.

Abstract: Photochromic organic–inorganic hybrid materials have attracted considerable attention owing to their potential application in photoactive devices, such as optical memories, windows, photochromic decorations, optical switches, filters or non-linear optics materials. The growing interest in this field has largely expanded the use of photochromic materials for the purpose of improving existing materials and exploring new photochromic hybrid systems. This tutorial review summarizes the design and preparation of photochromic hybrid materials, and particularly those based on the incorporation of organic molecules in organic–inorganic matrices by the sol–gel method. This is the most commonly used method for the preparation of these materials as it allows vitreous hybrid materials to be obtained at low temperatures, and controls the interaction between the organic molecule and its embedding matrix, and hence allows tailoring of the performance of the resulting devices.