Organic Materials for Reversible Optical Data Storage

Almost three decades ago, the field of nonlinear optics evolved with the discovery of lasers. In the beginning, nonlinear optical (NLO) phenomena were investigated in inorganic materials, leading to the development of traditional NLO materials such as lithium niobate, potassium titanyl phosphate, quartz and gallium arsenide. In the 1970s, the importance of organic materials was realized because of the promise of large NLO responses, high laser damage thresholds, fast optical responses, architectural flexibility and ease of fabrication. Following work with organic materials, the scrutiny of organometallics also began recently. In organometallics, the metal-ligand bonding is expected to display large molecular hyperpolarizability because of the transfer of electron density between the metal atom and the conjugated ligand system. In organometallics, the diversity of central metals, oxidation states and ligands fosters in optimization of the charge-transfer interactions. Keeping this in view, second- and third-order NLO properties of organometallics have been reviewed here, highlighting new materials that are emerging. Organometallics may have a wide range of applications in opto-electronics including integrated optics, optical switching, telecommunications, bistability and modulation.

Organometallic materials for nonlinear optics

Optical Nonlinearity:Phenomena, applications, and materials

We demonstrate an 80-μm-thick film (which is around 15% of the thickness of the human epidermis), which is a highly sensitive hybrid functional gauge sensor, and was fabricated from poly(vinylidene fluoride) (PVDF) and ZnO nanostructures with graphene electrodes Using this film, we were able to simultaneously measure pressure and temperature in real time The pressure was monitored from the change in the electrical resistance via the piezoresistance of the material, and the temperature was inferred based on the recovery time of the signal Our thin film system enabled us to detect changes in pressure as small as 10 Pa which is pressure detection limit was 10(3)-fold lower than the minimum level required for artificial skin, and to detect temperatures in the range 20-120 °C

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Highly Sensitive and Multifunctional Tactile Sensor Using Free-standing ZnO/PVDF Thin Film with Graphene Electrodes for Pressure and Temperature Monitoring

Phthalocyanine-based Langmuir-Blodgett films as chemical sensors.

The present status of research on Langmuir-Blodgett (LB) films is outlined in relation to specific properties for electronic applications. The fundamentals of LB films are briefly described such as preparation techniques, film types, structure, and suitable compounds for functional amphiphiles, unconventional film-forming materials and polymers. Stress is laid on novel functional LB films exhibiting either photochemical and thermal reactivity, or electroactive properties such as electrical conduction, redox activity, electrochromism, nonlinear optical properties, and pyroelectric activity. The current status of LB films with regard to electronic applications is described, e.g. as photo- or e-beam resists, information storage systems, barrier layers, chemisensors, frequency converters and modulators, optical switches, guided wave structures or infrared sensors. Prospects for future molecular electronic devices are also briefly discussed.

Langmuir–blodgett films for electronic applications

The current status of Langmuir–Blodgett (LB) films is described with regard to biomimetic applications as separating membranes and sensor layers. In the first part, recent research activities on the utility of LB membranes for gas separation, liquid permeation, hyper- and ultrafiltration are reviewed. The morphological aspects of materials separation in LB films are discussed. In the second part, recent progress in the rapidly growing field of LB-film-based chemical sensors and blosensors is reviewed. The structure and function of gas and ion sensors, and enzyme and immunosensors is briefly discussed. Perspectives for future activities in the fields of LB membranes and sensors are outlined.

Bernd Tieke

Papers

Langmuir–blodgett films for electronic applications

Langmuir–Blodgett membranes for separation and sensing

A novel Langmuir–Blodgett film of a dibenzylideneacetone–Pd(0) complex and its use for preparation of catalytically active substrates