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

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

Cyanines during the 1990s: A Review

CsSnI3 is an unusual perovskite that undergoes complex displacive and reconstructive phase transitions and exhibits near-infrared emission at room temperature. Experimental and theoretical studies of CsSnI3 have been limited by the lack of detailed crystal structure characterization and chemical instability. Here we describe the synthesis of pure polymorphic crystals, the preparation of large crack-/bubble-free ingots, the refined single-crystal structures, and temperature-dependent charge transport and optical properties of CsSnI3, coupled with ab initio first-principles density functional theory (DFT) calculations. In situ temperature-dependent single-crystal and synchrotron powder X-ray diffraction studies reveal the origin of polymorphous phase transitions of CsSnI3. The black orthorhombic form of CsSnI3 demonstrates one of the largest volumetric thermal expansion coefficients for inorganic solids. Electrical conductivity, Hall effect, and thermopower measurements on it show p-type metallic behavior w...

CsSnI3: Semiconductor or Metal? High Electrical Conductivity and Strong Near-Infrared Photoluminescence from a Single Material. High Hole Mobility and Phase-Transitions

Photo-, thermo-, solvato-, and electrochromic spiroheterocyclic compounds.

Organic photoresponse materials and devices are critically important to organic optoelectronics and energy crises. The activities of photoresponse in organic materials can be summarized in three effects, photoconductive, photovoltaic and optical memory effects. Correspondingly, devices based on the three effects can be divided into (i) photoconductive devices such as photodetectors, photoreceptors, photoswitches and phototransistors, (ii) photovoltaic devices such as organic solar cells, and (iii) optical data storage devices. It is expected that this systematic analysis of photoresponse materials and devices could be a guide for the better understanding of structure–property relationships of organic materials and provide key clues for the fabrication of high performance organic optoelectronic devices, the integration of them in circuits and the application of them in renewable green energy strategies (critical review, 452 references).

Organic photoresponse materials and devices

A spectrophotometric and fluorimetric study of some anthraquinoid and indigoid colorants used in artistic paintings

After electronic excitation by ultraviolet or visible radiation, atoms and molecules can undergo thermal or radiative deactivation processes before relaxing to the ground state. They can emit photons with longer wavelengths than the incoming exciting radiation, that is, they can fluoresce in the UV−vis−near-infrared (NIR) range. The study of fluorescence relaxation processes is one of the experimental bases on which modern theories of atomic and molecular structure are founded. Over the past few decades, technological improvements in both optics and electronics have greatly expanded fluorimetric applications, particularly in analytical fields, because of the high sensitivity and specificity afforded by the methods. Using fluorimetry in the study and conservation of cultural heritage is a recent innovation. In this Account, we briefly summarize the use of fluorescence-based techniques in examining the constituent materials of a work of art in a noninvasive manner. Many chemical components in artwork, espec...

Fluorescence spectroscopy: a powerful technique for the noninvasive characterization of artwork.

Acidichromic effects in 1,2-di- and 1,2,4-tri- hydroxyanthraquinones. A spectrophotometric and fluorimetric study

In this paper, a treatment of the spectroscopic data from thermoreversible photochromic systems is described which allows the molar absorption coefficient of the metastable photomerocyanine, the quantum yield of the colour-forming reaction and the kinetic parameters of the thermal bleaching to be determined. The results obtained for five spiroindoline-oxazines indicate that “colourability” on steady state irradiation depends on the photomerocyanine molar absorption coefficient, quantum field and bleaching rate coefficient. For the molecules investigated, the “colourability” markedly depends on temperature, due to the temperature dependence of the bleaching reaction. The results obtained are compared with literature “colourability scales”, determined empirically by comparison of different systems excited by pulsed light.

Thermally reversible photoconversion of spiroindoline-naphtho-oxazines to photomerocyanines: a photochemical and kinetic study

In this work the photochromic behaviors of four Reversacol compounds from James Robinson Ltd., previously investigated in solution, have been studied in a microcrystalline solid phase and embedded in a poly(methyl methacrylate) matrix (PMMA). The compounds studied belong to the classes of spirooxazines and naphthopyrans. In solution, they showed photocoloration and thermocoloration. Embedded into polymeric films, as well as in the microcrystalline phase, they have maintained their photochromic and thermochromic behavior. The photocoloration quantum yields in PMMA were determined and found to be fairly high. Compared to solution, the kinetic and thermodynamic activation parameters of thermal bleaching significantly changed. The solid environment has the effect of slowing down the bleaching rates in films as well in the pure crystalline phase and introduces multiexponential terms in the photocoloration and thermal bleaching kinetics. Activation enthalpy and entropy decrease, compared to solution, leaving th...

Giovanna Favaro

Papers

A spectrophotometric and fluorimetric study of some anthraquinoid and indigoid colorants used in artistic paintings

Fluorescence spectroscopy: a powerful technique for the noninvasive characterization of artwork.

Acidichromic effects in 1,2-di- and 1,2,4-tri- hydroxyanthraquinones. A spectrophotometric and fluorimetric study

Thermally reversible photoconversion of spiroindoline-naphtho-oxazines to photomerocyanines: a photochemical and kinetic study

Photochromism and Thermochromism of some Spirooxazines and Naphthopyrans in the Solid State and in Polymeric Film