Ternary polymer solar cells based on a polymer PTzBT have received a lot of attention because their power conversion efficiency (PCE) and thermal stability have been greatly improved by adding a small amount of an oligomer ITIC. However, the charge-accumulation states of the PTzBT ternary polymer solar cells have not yet been completely clarified. Here, we report electron spin resonance (ESR) spectroscopy of the PTzBT ternary polymer solar cells to investigate the charge-accumulation states from a microscopic viewpoint with examining the effect of UV-light irradiation. We observed a slight increase in the ESR intensity of the PTzBT cells and layered film samples under simulated solar irradiation with a UV-cut filter. Multiple signals were observed in the PTzBT cells under solar irradiation when the UV-cut filter was removed. Interestingly, no decrease was observed in the ESR signal of ZnO under solar irradiation with the UV-cut filter, although holes in ZnO in the PTzBT cells are known to decrease under solar irradiation. These findings will contribute to a deep understanding of the material properties of polymer solar cells.

Lead-free Sn(II) based, CsSn₂Br₅, perovskite nanocubes were synthesized using a modified hot-injection method by tuning the injection temperature and reaction conditions. The formation of Sn(IV) based, Cs₂SnBr₆, perovskite nanocrystals (PNCs) from CsSn₂Br₅ perovskite nanocubes was observed. X-ray diffraction measurements revealed that oxygen or water molecules in air gradually react with CsSn₂Br₅ perovskite nanocubes to form Cs₂SnBr₆ NCs. The stability of Cs₂SnBr₆ NCs was monitored by time-dependent absorption measurements. Both oxygen and water molecules react with the Cs₂SnBr₆ NCs to degrade, however water molecules appears largely to react with the NCs. The stability has been improved by dispersing the Cs₂SnBr₆ NCs in degassed anhydrous solvent.

Conjugated polymers encompassing delocalized π-electrons in their backbones exhibit high photoabsorption and efficient charge carrier transport through the intermolecular π-π stacking suitable for organic photovoltaics (OPV). By contrast, small molecules such as [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives, which demonstrates high field-effect transistor hole mobilities owing to their 2-dimensional herringbone packing, have not yet been applied to OPVs. Here we report a non-conjugated backbone polymer bearing phenyl- and decyl-substituted BTBT (Ph-BTBT-10) as the pendant conjugated unit, which was synthesized by ring opening polymerization of epoxy append. The polymer showed an X-ray diffraction pattern ascribed to the layered lamellar and less ordered herringbone packing. In addition, a model molecule of Ph-BTBT-10 showed charge separation upon photoexcitation when blended with a non-fullerene acceptor (ITIC) or fullerene (PCBM).

Cicada wings consist of nanopillar arrays with a pitch, diameter, and height of a few hundred nanometers. These arrays show strong antibacterial performance owing to cell membrane damage caused by the physical interaction with the nanopillars. Polymer-based nanopillars are essential for various industrial applications. Herein, we present the fabrication process of polymer-based nanopillars using a facile thermal nanoimprint technique. Moreover, the conformational information of the nanopillars has been provided.

Microchannels have been studied actively in recent years. Various types of materials are used for fabricating microchannels in different types of applications including polymers, and ceramics. Since glass materials have appealing properties such as hardness, transparency, thermal resistance, and chemical resistance, they are used in biomedical devices and microfluidic application. Glass microchannel fabrication methods include chemical etching, imprinting, and 3D printing. This paper proposes unprecedented methods to fabricate glass microchannels using plant roots growth and nematodes migration. The microchannels fabricated by these methods have a complex three-dimensional structure, and the smallest channels have a diameter of several tens of micrometers in the glass. Although glass is attractive material, it is challenging to sinter the green body to fully dense and transparent solid structure. Hence, experiments were also conducted to establish a fabrication technique for transparent silica glass.

In this paper, a simple but effective method is proposed to generate a bio-mimic wave propagating motion in a magnetic soft actuator. Two examples, a metachronal wave in artificial cilia and a crawling motion of an artificial caterpillar, are shown as demonstrations. These are kinds of wave propagating motions which are popular in natural systems and are also primitive systems of natural creatures. In the proposed system, an elastic material and a magnetic powder were used to fabricate a flexible magnetic structure. There are 2 essential features in the system; one is periodic arrangement of magnetic anisotropy, and the other is application of a rotating magnetic field. Using this method of wave generation, we realized drastic change in flow making behavior of artificial cilia and a crawling motion very similar to living caterpillars. The proposed system would be useful to enhance the field of the bio-mimic soft robotics.

Bile duct stent placement surgery is often performed to improve bile flow that has been impaired by biliary stricture. Conventional stents made of polyethylene cause blockage easily. We were inspired by the antifouling function of snail shells as a method for preventing blockages. For this study, we fabricated microstructures directly on the interior wall of the stent using an atmospheric pressure low-temperature plasma and verified its antifouling function. Plasma treatment fabricated microstructures, thereby improving the surface area by 2.1 times and roughness by 1.4 times. Results of animal experiments revealed that the substance adhering on the interior wall of the plasma-treated stent was about 40% less than those of the untreated stent. The plasma-treated stent can contribute considerably to reducing the burdens of surgery on patients by decreasing the frequency of replacement surgery.

Endoscopes are widely used in clinical settings. Gastric endoscopes in particular are useful for detecting early-stage gastric cancers and polyp removal. During polyp removal or other simple surgical procedures, however, the spatter of blood and bodily fluids resulting from excision of the affected areas can fog the endoscope lens. Condensation caused by temperature differences between the instrument interior and exterior can also affect image clarity. Any obstruction of the field of view during the surgical procedure must be addressed by removing the endoscope and cleaning the lens; however, doing so prolongs the time required for the procedure, makes it more invasive, and increases patient burdens. Drawing on biomimicry principles, we developed an endoscope lens with anti-fogging and anti-fouling features. This paper reports our results.

A surface-enhanced Raman scattering (SERS) active structure allows the highly sensitive imaging of label-free molecular trace. A gold nanostructure with boehmite as a skeleton was fabricated by the inclined magnetron sputtering method. The characteristics of the prepared SERS imaging plate consisting of gold nanostructure on boehmite were evaluated as the follows. The distance dependence of the SERS intensity of 4,4′-bipyridine from the edge of the substrate indicated that the larger the SERS intensity becomes as the closer the distance approaches the substrate edged where the gold nanolayer was thicker. The trend of SERS dependence on distance was more pronounced at higher concentration of molecule and less pronounced at lower concentration. Using the SERS imaging plate will enable the further demonstration of ultrasenstive detection of chemical and biological molecules as environmental contaminants within a broad range of common fluidics for potential applications related to analytical chemistry and environmental monitoring.

The soft X-ray absorption spectroscopy (XAS) spectra of Alanine, L- and D-phenylalanine, and L- and D-tyrosine dissolved in a solid state were measured at BL17SU of SPring-8. The spectra exhibited characteristic features dependent on the molecular structure. It was found that almost the same spectra were obtained for Alanine and Phenylalanine, while for Tyrosine, the spectral shape indicated a drastic change owing to the existence of the oxygen 1s → π* transitions of COO¯. It is found that the X-ray irradiation promotes the destruction reaction of amino acids and changes the spectral shape during the spectroscopic measurement. The molecular destruction rate by X-ray was estimated from the change of spectral intensity as a function of irradiation time. Our results indicate that the ratio of the destruction rate depends on the molecular structure and is facilitated by the oxygen 1s → π* transitions.

In this paper, we report low temperature curable (around 200～250℃), low Dk (2.7) and low Df (0.007) negative tone type photo-definable polyimides. Those materials, which were in states of liquid or B-stage sheet, were able to be patterned by photolithography process. Our novel polyimides showed excellent dielectric and mechanical properties, and good results on reliability tests. Our developed polyimides kept enough insulating performance after a biased HAST (High Accelerated Stress Test). Finally, in collaboration with IME, a test package which mounted our novel polyimide as redistribution layers was fabricated.

The synthesis of polyimides (PIs) containing polydimethylsiloxane (PDMS) with controlled chain length and the formation of higher-order structures were studied. Polycondensation was carried out using diphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA) and diamine oligomers having amino groups on both ends of PDMS. The obtained poly(amic acid) (PAA) and PI showed good solubility in several common polar solvents while less soluble in non-protic amide polar solvents. The obtained bulk films of PI suggested forming a microphase-separated structure with domains based on PDMS and other aromatic moieties.

Polyimides have been widely used as high-performance polymers, but controlling their morphology is still challenging. This study focuses on fabricating spherical polyimide particles by the precipitation polymerization of diamine and tetracarboxylic dianhydride monomers. Polyimide particles were prepared by changing the concentration and structure of the monomers in the presence of a dispersant, and the effect of these conditions on the size and distribution of the particles are discussed. The effect of crosslinking by a triamine monomer is also described.

The polyguanamines were prepared by the polymerization of bis[N-(2-anilino-4-chloro-1,3,5-triazine)yl]-4,4’-oxydianiline (Bis(ACT)) with α,ω-alkylene diamines such as 1,12-diaminododecane, 1,10-diaminodecane and 1,8-diaminooctane. The NMR analysis of Bis(ACT) and the resulting polyguanamines showed that the hydrogen bonds cause between triazine and adjacent anilino units. The resulting polyguanamines have good solubility in typical organic solvent. Temperatures where 5% weight losses of the polyguanamines occur under N₂ flow are in the rage of 435-449℃. The glass transition temperatures (T_g) are in the range of 133-156℃. Almost colorless and flexible films were successfully prepared by a solution casting method. The optical transmittance of films was high as 80% at 400 nm. Furthermore, the films exhibited high reflective index around 1.67.

Particle-agglomerated films exhibit rough surfaces, which can be suitable for realization of ultra hydrophobicity. We fabricated particles and their deposits of silica with organic functional groups (SiO:CH) by plasma polymerization of organosilicon reactants including methyl and vinyl functional groups. The trimethyl(vinyl)silane reactant showed a uniform deposition of the plasma-polymerized SiO:CH particles in a large area, while the trimethyl (vinyloxy)silane exhibited a localized particle deposition.