Photocatalytic CO₂ reduction has attracted attention as a potential means of addressing the problems of global warming and the depletion of fossil fuels. Recently, hybrid photocatalysts constructed with a metal complex and a particulate semiconductor are of particular interest because of the excellent electrochemical (and/or photocatalytic) ability of the metal complexes for CO₂ reduction and the high efficiency of the semiconductors for oxidation reactions. This article describes our recent progress in the development of metal-complex/semiconductor hybrid photocatalysts for visible-light-driven CO₂ reduction.

Experimental results and future prospects of in situ synchrotron X-ray reciprocal space mapping (in situ RSM) developed for studying the crystal growth dynamics of compound semiconductors are presented. In situ RSM enables the observation of both the strain and quality of crystals during growth at a high speed comparable to the growth of a single atomic layer. Initial growth dynamics of GaN/SiC and the strain relaxation mechanisms of InGaAs/GaAs are explained on the basis of experimental results of in situ RSM. Moreover, the in-plane anisotropic strain relaxation of InGaAs films was revealed using 3D-RSM. In situ RSM has proved to be a powerful characterization tool for studying not only fundamental crystal growth dynamics but also device structures with multilayers such as solar cells.

High pressure techniques are powerful tools that can directly adjust the crystal structure and electric state of functional materials. A diamond anvil cell (DAC) is a unique tool to perform a physical property measurement above 100 GPa, however, its experiments are extremely difficult. Therefore, we have developed a new DAC with boron-doped metallic diamond electrodes and undoped diamond insulating layer. We can easily measure the resistivity under high pressure because the electrodes and insulating layer are very stable for pressure. In this paper, we report the fabrication process of the new DAC and the results of the resistivity measurements of the thermoelectric material SnSe and the Fe-based superconductor FeSe under high pressure.

Highly bi-axially oriented poly-Si thin films were successfully fabricated on quartz substrates by multi-line beam continuous wave laser crystallization. The crystallinity was controlled to be {211}-{110}-{111} or {100}-{100}-{100} crystal grains by changing the laser-crystallization conditions. By using the {100} poly-Si thin film, ultra-high mobility poly-Si TFTs were demonstrated. The highest field effect mobility was 1010 cm²/Vs. The relationship between the mobility and the TFT channel’s crystallinity was also investigated.

In recent years, OLEDs have finally realized nearly 100% internal quantum efficiency from electricity into photons by using sophisticated phosphorescence and TADF emitters. Therefore, the development of an organic semiconductor laser diode (OSLD) as a post-OLED is greatly anticipated. Since many organic molecules form four energy levels owing to the Stokes-shift, they demonstrate inherently excellent lasing performance as a low threshold laser material. In this article, with the aim of a future current injection laser, quasi-CW oscillation phenomena under photoexcitation are reviewed with an excellent laser molecule of 4,4'-bis ([N-carbazole] styryl) biphenyl (BSB-Cz).

When light is irradiated to polymers having azobenzene moieties as side-chains (azo-polymers), the polymer is deformed by molecular movement during photo-isomerization. By utilizing this phenomena, photon energy can be directly converted to mechanical energy, which results in the realization of a mechanical function and its application to molecular nano-machines driven by light. Moreover, the optical near-field around nano-structures, which cannot be observed by a normal optical microscope due to the diffraction limit of light, can be observed by utilizing the property that the induced deformation pattern is dependent on the incident light intensity distribution and the state of the light polarization. In this report, we review light-induced mass movement in azo-polymers, and then show its application to nano-imaging of a plasmonically enhanced near-field in the vicinity of single gold nano-particles.

A new electret technique named the potassium ion electret is introduced. Potassium ions are incorporated into an oxide film during a thermal oxidation process and then taken out from the oxide by applying a DC voltage at a high temperature. As a result, we have now demonstrated the remaining oxygen deficiencies are negatively charged and give an electret voltage up to 400V. A vibration energy harvesting device fabricated by using this electret technique is presented, as well as a charging experiment driven by an actual acceleration obtained on a highway. Other devices that have a new function due to this electret technique are also touched upon briefly.

A total-internal reflection fluorescence microscope is an optical microscope that uses an evanescent field that illuminates only the sample vicinity of the glass substrate. By largely decreasing the background light with the evanescent field, real-time imaging of single fluorescent dyes in an aqueous environment at room temperature becomes possible. In this Fundamental Lecture, the basic principles and construction methods of the total-internal reflection fluorescence microscope will be explained.