Organic radicals have been attracted much attention from the viewpoints of not only synthetic chemistry but also materials science. Longer-wavelength absorptions and emissions, and reversible redox properties are of the typical advantages of organic radicals, as compared with closed-shell molecules. Therefore, the radicals are listed as important candidates of functional materials for electronic devices. In this review, we describe the latest science and application of organic radicals for secondary battery, semiconductor, and photochromism. We also review our recent results and the concept of organic light-emitting diode utilizing organic radicals as an emitter, which is called “organic radical light-emitting diode (ORLED)”.
Organic light-emitting diodes (OLEDs) fabricated using wet process has attracted great interests because of the usefulness for large-area display and lighting. Conjugated polymers suitable for the process are prepared using Suzuki-Miyaura coupling reaction. In this report, we show the effect of the preparing and purifying methods of polymer on the properties of the device. In addition, a newly designed crosslinkable hole-injection/transport oligomer, which is applicable for multilayered and printed OLED, is demonstrated.
This article describes recent research progress in colorants and liquid crystals developed by FUJIFILM Corporation. Recent topics in colorants based on three key technologies are as follows; 1)application of photo-induced energy conversion technology to dyes for DVD, 2)development of dye for Dye Diffusion Thermal Transfer (D2T2) and inkjet printing system based on chromogenesis technology, and 3)syntheses of new heterocyclic compounds such as 2-aminopyrroles for useful intermediates and triazines for UV absorbers. Liquid crystal technology from the representative discotic compound is directed toward four areas that are 1)synthetic technology for stable supply of the discotic compound on an industrial scale, 2)new functional materials using discotic liquid crystals such as ubricants, 3)expansion to calamitic liquid crystals for “selective reflective type” color filter for LCD, and 4)application to guest-host liquid crystal mode. In the last part “base and core technology” of organic materials owned by FUJIFILM is introduced. We are continuously studying to produce innovative materials with the key message “Change the world with light and color”.
Organic luminescent materials have been regarded as one of the most important key materials in the fields of various applications such as fluorescent paints, fluorescent brightening agents, wavelength-conversion films for agricultural use, dye lasers, bioanalytical luminescent probes, piezo- and tribochromic luminescent devices, organic light-emitting devices, and so on. In order to achieve the purposes, they have been well designed and their functionality has been finely tuned by introduction of some functional groups and subunits. Nowadays, the development of organic luminescent materials is about to go to the industrial stage, and highly functionalized luminescent materials are enthusiastically developed towards practical and versatile demands, using wide range of synthetic technology from classical synthetic methods to new types of cross-coupling reactions using transition metal-based catalysts. Here we show recent research developments of organic luminescent materials, especially focusing on applications to organic electronic devices and the relevant.
Organic electroluminescent display (OLED) has been paid much attention because OLED has high contrast ratio, short response time, and wide viewing angle. OLED is manufactured by vacuum evaporation process or solution process. OLED manufactured by vacuum process is currently used in small display such as smart phones and cellular phones. Display makers are focusing on development of large area display such as TV at this moment. Solution process is attractive for TV because it can be manufactured for large area display with low cost. Light emitting polymer (LEP) is one of most promising material for display manufactured by solution process. In this paper, we describe development of LEP in Sumitomo-Chemical, for example, improvement of efficiency and lifetime, and show the latest materials performance from these studies.
In this article, the synthesis and fundamental properties of [2.2]paracyclophane-containing through-space conjugated polymers are described. By incorporating pseudo-para-, pseudo-ortho-, and pseudo-geminal-linked [2.2]paracyclophane skeletons into conjugated polymer main chains, through-space conjugated polymers comprising stacked π-electron systems can be prepared. Our recent works in this filed are especially focused on, and the characteristic features of the through-space conjugated polymers constructed by [2.2]paracyclophane are summarized. Especially, we emphasize the role of [2.2]paracyclophane moiety in the polymer backbone as well as possibility for a single molecular wire that flows energy and charges in one direction via the through-space. In addition, conjugated microporous polymers containing the [2.2]paracyclophane skeletons are also briefly introduced.
A new dynamic covalent chemistry (DCC) system in the reaction of resorcinol and 1,5-pentanedial could be achieved, yielding a only soluble oligomer Noria (Noria means water wheel in Latin) in high yield, resembling a water-wheel in appearance. Application of the Noria derivatives with pendant photo-reactive groups were examined for UV-curing materials and photo-resist materials. The obtained Noria derivatives had good solubility, good film-forming ability, high thermal stability, and high photo-chemical reactivity. Furthermore, certain new ladder cyclic oligomers could be synthesized using a similar approach to that employed for the synthesis of Noria and their application as next generation resist materials was also investigated.
Only a few articles have mentioned photoreactive materials relying on base-catalyzed transformations have been reported. This is probably due to relatively low quantum yields for photobase generation and weaker basicity of photogenerated bases, leading to low photosensitivity of photoreactive materials sensitized with photobase generators (PBGs). We report here novel PBGs to release organic strong bases with high quantum yields and a novel concept of base proliferation to improve the photosensitivity of the photoreactive materials. The concept involves the base-catalyzed decomposition of an organic compound termed a base amplifier (BA) which produces a newborn base molecule, leading to its autocatalytic decomposition. The addition of BAs to the photoreactive materials resulted in the marked improvement of photosensitivity because the number of photogenerated base molecules increases markedly as a result of the base proliferation reaction of the doped BA.
Slide-ring materials, in which the cross-links are slidable on the backbone polymers, have advanced by many fundamental and applied studies since the first report in 2001. Over the past decade, almost all studies have concentrated on a uniform-backbone material for reasons of the availability. This article reviews our recent progress related to the materials with diverse backbones. Organic-inorganic hybrid slide-ring materials are synthesized from a polyrotaxane that consists of poly(dimethylsiloxane) and γ-cyclodextrin. The slidability of cross-links in the material promises dynamic changes in the relative positions of each component. Poly(butadiene)-based slide-ring materials enable us to find a novel viscoelastic relaxation attributed to the sliding dynamics of partial chains through cross-links. This suggests a dynamic transition between one state where the cross-links behave as fixed ones and another where they slide freely. The diversifying physical property and application are beginning to reveal universal phenomena and strategies of molecular designs in slide-ring materials.
Dye-sensitized solar cells (DSSCs) have received considerable attention because of high incident solar light-to-electricity conversion efficiency and low cost of production. To increase power conversion efficiency of DSSCs, it is important to develop the effective organic dye sensitizers. For this purpose, as a new class of donor-π-acceptor (D-π-A) dye sensitizers for DSSCs, we have designed and synthesized a series of D-π-A fluorescent dyes with carboxyl groups on different positions of a chromophore skeleton or with pyridine ring as electron-withdrawing-injecting anchoring group. On the basis of experimental results and MO calculations, we propose that, for developing high performance DSSCs, it is necessary to create an epoch-making molecular design capable of controlling not only photophysical and electrochemical properties of the dyes themselves but also molecular arrangement and/or orientation of the dyes on TiO2 surface to provide a good electron communication between the dyes and TiO2 electrode.
This review article describes design of fullerene derivatives having high lowest unoccupied molecular orbital (LUMO) levels to obtain high open-circuit voltage in organic thin-film photovoltaic cells. Introduction of organic electron-donating groups onto fullerene and reduction of the size of π-electron conjugated system of fullerene effectively raise fullerene’s LUMO levels, affording high performance organic photovoltaic devices. Addition of the dihydromethano group as the smallest carbon addend to fullerene to obtain 56π-electron fullerene derivatives is likely a promising strategy in this research.