/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

The development of white organic light-emitting diodes (OLEDs) holds great promise for the production of highly efficient large-area light sources. High internal quantum efficiencies for the conversion of electrical energy to light have been realized. Nevertheless, the overall device power efficiencies are still considerably below the 60-70 lumens per watt of fluorescent tubes, which is the current benchmark for novel light sources. Although some reports about highly power-efficient white OLEDs exist, details about structure and the measurement conditions of these structures have not been fully disclosed: the highest power efficiency reported in the scientific literature is 44 lm W(-1) (ref. 7). Here we report an improved OLED structure which reaches fluorescent tube efficiency. By combining a carefully chosen emitter layer with high-refractive-index substrates, and using a periodic outcoupling structure, we achieve a device power efficiency of 90 lm W(-1) at 1,000 candelas per square metre. This efficiency has the potential to be raised to 124 lm W(-1) if the light outcoupling can be further improved. Besides approaching internal quantum efficiency values of one, we have also focused on reducing energetic and ohmic losses that occur during electron-photon conversion. We anticipate that our results will be a starting point for further research, leading to white OLEDs having efficiencies beyond 100 lm W(-1). This could make white-light OLEDs, with their soft area light and high colour-rendering qualities, the light sources of choice for the future.

White organic light-emitting diodes with fluorescent tube efficiency

The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing analytical tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithography for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several experiments that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chemical warfare agents and several biological molecules.

Surface-Enhanced Raman Spectroscopy

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

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Lanthanide luminescence for functional materials and bio-sciences

Surface-enhanced Raman spectroscopy.

Hyper-Structured Molecules III

We have developed a novel multifunctional chromophore for photorefractive applications. This chromophore, a carbazole oligomer, possesses all the properties required for photorefractivity. Furthermore, because of its good film forming properties, it can be used for optical image processing. The photocarrier generation properties of this chromophore and its second-order nonlinear optical response in acceptor-substituted carbazoles were examined by xerographic discharge, second-harmonic generation, and electro-optic measurements. Photorefractivity was measured directly by two-beam coupling and four-wave mixing experiments.

Multifunctional Carbazole Oligomer for Monolithic Photorefractive Materials

The nonlinear optical properties of poly(1,9-decadiyne) (PDD), which has a diacetylene group in the main chain, were investigated. Using as-prepared films of PDD, no third harmonic generation (THG) was observed. However, after thermal treatment of PDD films, THG appeared and the third order susceptibility, χ(3), was determined to be 1.2×10−12 esu. These heat-treated films were very clear and had no absorption between 600 and 2500 nm. A slab waveguide of polymer thin film was formed on a quartz substrate and its light propagation properties was investigated.

/pdf/a-nonlinear-optical-waveguide-of-poly-1-9-decadiyne-59ikbg5jq6.pdf

A nonlinear optical waveguide of poly(1,9-decadiyne).

We have studied the growth process of 4-mercaptopyridine (4-PySH) self-assembled monolayers (SAMs) on Au(111) substrate, by scanning tunneling microscopy (STM). The three factors which were investigated for the domain formation of 4-PySH were; solvent effect, immersion time dependence and the impurity effect. STM imaging revealed that the solvent effect was very significant in determining the surface morphology of the 4-PySH SAM growth, which was not observed on X-ray photoelectron spectra (XPS). These results indicated that the solvent was an important factor in the domain formation process, especially ethanol which as a typical SAM solvent, assisted the reconstruction of 4-PySH domains on the substrate.

https://iopscience.iop.org/article/10.1143/JJAP.37.3620/pdf

Solvent Effect on Domain Formation of 4-Mercaptopyridine Self-Assembled Monolayers on Au(111) Substrate by Scanning Tunneling Microscopy

We examined both photoconductive and electro-optical properties of the monolithic photorefractive polymer. The photoconductive sensitivity of 1.2 × 10−12(S cm−1)/(W cm−2) was obtained under a field strength of 5 × 105V/cm and a wavelength of 534nm. The EO signals linearly increased with the poling electric field.

Hiroyuki Sasabe

Papers

Hyper-Structured Molecules III

Multifunctional Carbazole Oligomer for Monolithic Photorefractive Materials

A nonlinear optical waveguide of poly(1,9-decadiyne).

Solvent Effect on Domain Formation of 4-Mercaptopyridine Self-Assembled Monolayers on Au(111) Substrate by Scanning Tunneling Microscopy

Xerographic and electro-optic studies of a photorefractive polymer