In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Organic Photoredox Catalysis

Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

The design and realization of metallic nanostructures with tunable plasmon resonances has been greatly advanced by combining a wealth of nanofabrication techniques with advances in computational electromagnetic design. Plasmonics — a rapidly emerging subdiscipline of nanophotonics — is aimed at exploiting both localized and propagating surface plasmons for technologically important applications, specifically in sensing and waveguiding. Here we present a brief overview of this rapidly growing research field.

https://dsl.nju.edu.cn/litao/res/Plasmonic%20review/%5bReview%20article%5d%20nphoton.2007%20Photonic-Nano-optics%20from%20sensing%20to%20waveguiding.pdf

Nano-optics from sensing to waveguiding

In the Raman effect, incident light is inelastically scattered from a sample and shifted in frequency by the energy of its characteristic molecular vibrations. Since its discovery in 1927, the effect has attracted attention from a basic research point of view as well as a powerful spectroscopic technique with many practical applications. The advent of laser light sources with monochromatic photons at high flux densities was a milestone in the history of Raman spectroscopy and resulted in dramatically improved scattering signals (for a general overview of modern Raman spectroscopy, see refs 1-5). In addition to this so-called spontaneous or incoherent Raman scattering, the development of lasers also opened the field of stimulated or coherent Raman spectroscopies, in which molecular vibrations are coherently excited. Whereas the intensity of spontaneous Raman scattering depends linearly on the number of probed molecules, the coherent Raman signal is proportional to the square of this number (for an overview, see refs 6 and 7). Coherent Raman techniques can provide interesting new opportunities such as vibrational imaging of biological samples,8 but they have not yet advanced the field of ultrasensitive trace detection. Therefore, in the following article, we shall focus on the spontaneous Raman effect, in the following simply called Raman scattering. Today, laser photons over a wide range of frequencies from the near-ultraviolet to the near-infrared region are used in Raman scattering studies, allowing selection of optimum excitation conditions for each sample. By choosing wavelengths which excite appropriate electronic transitions, resonance Raman studies of selected components of a sample or parts of a molecule can be performed.9 In the past few years, the range of excitation wavelengths has been extended to the near-infrared (NIR) region, in which background fluorescence is reduced and photoinduced degradation from the sample is diminished. High-intensity NIR diode lasers are easily available, making this region attractive for compact, low cost Raman instrumentation. Further, the development of low noise, high quantum efficiency multichannel detectors (chargecoupled device (CCD) arrays), combined with highthroughput single-stage spectrographs used in combination with holographic laser rejection filters, has led to high-sensitivity Raman spectrometers (for an overview on state-of-the-art NIR Raman systems, see ref 10). As we shall show in section 2, the nearinfrared region also has special importance for ultrasensitive Raman spectroscopy at the singlemolecule level. As with optical spectroscopy, the Raman effect can be applied noninvasively under ambient conditions in almost every environment. Measuring a Raman spectrum does not require special sample preparation techniques, in contrast with infrared absorption spectroscopy. Optical fiber probes for bringing excitation laser light to the sample and transporting scattered light to the spectrograph enable remote detection of Raman signals. Furthermore, the spatial and temporal resolution of Raman scattering are determined by the spot size and pulse length, respectively, of the excitation laser. By using a confocal microscope, Raman signals from femtoliter volumes (∼1 μm3) can by observed, enabling spatially resolved measurements in chromosomes and cells.11 Techniques such as multichannel Hadamard transform Raman microscopy12,13 or confocal scanning Fourier transform Raman microscopy14 allow generation of high-resolution Raman images of a sample. Recently, Raman spectroscopy was performed using near-field optical microscopy.15-17 Such techniques overcome the diffraction limit and allow volumes significantly smaller than the cube of the wavelength to be investigated. In the time domain, Raman spectra can be measured on the picosecond time scale, providing information on short-lived species such as excited 2957 Chem. Rev. 1999, 99, 2957−2975

Ultrasensitive Chemical Analysis by Raman Spectroscopy

Synthetic Principles for Bandgap Control in Linear pi-Conjugated Systems.

A stable, high-mobility ZnO thin-film semiconductor was fabricated by thermal treatment of a solution-deposited thin film from a solution of Zn(OAc)2/2-ethanolamine in methoxyethanol. This ZnO thin-film semiconductor was composed of closely packed ZnO single crystals (∼30 to 50 nm) having a hexagonal structure assuming a preferred orientation with its c-axis perpendicular to the substrate. Field-effect mobility of 5−6 cm2 V-1 s-1 and current on-to-off ratio of 105−106 were demonstrated with this ZnO thin-film semiconductor in thin-film transistors.

Stable, solution-processed, high-mobility ZnO thin-film transistors.

Disclosed is an improved layered photoresponsive imaging member comprised of a supporting substrate; a vacuum evaporated photogenerator layer comprised of a perylene pigment selected from the group consisting of a mixture of bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline-6,11-dione, and bisbenzimidazo(2,1-a:2',1'-a)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline-10,21-dione, and N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide); and an aryl amine hole transport layer comprised of molecules of the following formula: ##STR1## dispersed in a resinous binder and wherein X is selected from the group consisting of halogen and alkyl.

Photoconductive imaging members with perylene pigment compositions

Effect of viscosity and temperature on torsional relaxation of molecular rotors

A series of fluorescence probes (p-(N,N-dialkylamino) benzylidene malononitriles) which belong to a class of organic compounds known as “molecular rotors” has been developed. The internal molecular rotation of these compounds can be slowed down by increasing the surrounding media rigidity, viscosity or decreasing the free-volume available for molecular relaxation. Inhibition of internal molecular rotation of the probe leads to a decrease in the non-radiative decay rate and consequently enhancement of fluorescence. This behavior can be used to study both the static and dynamic changes in free-volume of polymers as a function of polymerization reaction parameters, molecular weight, stereo regularity, crosslinking, polymer chain relaxation and flexibility. In addition, the dependence of the fluorescence emission maximum of these probes on media polarity allow continuous monitoring of the probes location in the polymer matrix. These fluorescence materials are capable of simultaneously probing the flexibility and polarity of the surrounding media.

Fluorescence probes for polymer free-volume

Les films de Langmuir-Blodgett (LB) d'acide arachidique sont utilises comme cales d'espacement pour controler la distance de separation entre des films a ilots de metal Ag et In vaporises et des couches monomoleculaires de LB de phtalocyanine legerement substituee. Les mesures des intensites relatives permettent de determiner la relation entre la distance et le facteur d'augmentation de la diffusion Raman augmentee en surface dans le cas des phtalocyanines

Rafik O. Loutfy

Papers

Stable, solution-processed, high-mobility ZnO thin-film transistors.

Photoconductive imaging members with perylene pigment compositions

Effect of viscosity and temperature on torsional relaxation of molecular rotors

Fluorescence probes for polymer free-volume

Distance dependence of SERS enhancement factor from Langmuir-Blodgett monolayers on metal island films: evidence for the electromagnetic mechanism