The artificial photosynthesis technology known as the Honda-Fujishima effect, which produces oxygen and hydrogen or organic energy from sunlight, water, and carbon dioxide, is an effective energy and environmental technology. The key component for the higher efficiency of this reaction system is the anode electrode, generally composed of a photocatalyst formed on a glass substrate from electrically conductive fluorine-doped tin oxide (FTO). To obtain a highly efficient electrode, a dense film composed of a nanoparticulate visible light responsive photocatalyst that usually has a complicated multi-element composition needs to be deposited and adhered onto the FTO. In this study, we discovered a method for controlling the electronic structure of a film by controlling the aerosol-type nanoparticle deposition (NPD) condition and thereby forming films of materials with a band gap smaller than that of the prepared raw material powder, and we succeeded in extracting a higher current from the anode electrode. As a result, we confirmed that a current approximately 100 times larger than those produced by conventional processes could be obtained using the same material. This effect can be expected not only from the materials discussed (GaN-ZnO) in this paper but also from any photocatalyst, particularly materials of solid solution compositions.

A dense, thick, and organic‐binder‐free ceramic film consisting of stress‐free nanoparticles could be obtained at room temperature by making use of the unstable and high‐surface energy amorphous phase on the surface of particles. Photolithography and wet etching can be adapted to the thick ceramic green‐state film. A multilayered structure consisting of various ceramics with different sintering temperatures and Cu wiring can form on a Cu foil below 1000 °C.

Embedded capacitors can effectively decrease the size of electronic appliances. This application prefers the use of dielectric films with a high dielectric constant prepared by low‐temperature processes. In the present paper, we report the preparation, characterization, and dielectric properties ranging from 10 kHz to 1 MHz of BaTiO3/epoxy and BaTiO3/Al composite films, processed at a low temperature. In the BaTiO3/resin composites, the ceramic content is limited and a maximum dielectric constant of 150 is obtained. A dense composite film of BaTiO3 particles having varying grain sizes and prepared by aerosol deposition showed a maximum dielectric constant of 400. However, BaTiO3/aluminum composite showed a high dielectric constant of >30,000 due to the percolation effect.

The rapid evolution in electronic equipment has created a demand for advanced devices that are flexible, thin, and light in weight. This demand is driving the development of a core technology for flexible and stretchable electronic devices. To produce wearable computers, we need to fabricate functional membranes that contain passive devices, such as capacitors and resistors, on resin sheets at low temperatures. These sheets can then serve as mounting boards for various electronic devices. By improving the technique for room-temperature aerosol-type nanoparticle deposition of a ceramic material, we have established a technology for forming a dielectric inorganic BaTiO3 film with an excellent degree of crystallinity and favorable electric properties for use in the production of flexible and stretchable electronic devices on a polyimide sheet. By this method of forming a homogeneous nanoparticle structure inside a film, we produced a capacitor film with a dielectric constant of 200 on a polyimide sheet at room temperature.

No abstract