A reproducible method for preparing the SrTiO3(100)-c(2 & times; 2) surface reconstruction was developed using \/ \/ molecular beam epitaxy (MBE). The formation processes of the c(2 & times; 2) and ( 13 & times; 13) surface reconstructions were investigated by reflection high-energy electron diffraction (RHEED). A flat c(2 & times; 2) surface reconstruction \/ \/ was obtained by Sr deposition onto the ( 13 & times; 13) surface at a substrate temperature of 800 degrees C under an oxygen atmosphere of 1.0 & times; 10-4 Pa. Subsequent Ti deposition onto the c(2 & times; 2) surface resulted in the \/ \/ reformation of the ( 13 & times; 13) surface, indicating reversible switching between the two reconstructions. Furthermore, RHEED observations during Sr and Ti deposition provide a phenomenological description of the formation processes of both surface reconstructions.

The alignment of nematic liquid crystal (NLC) molecules at the interface between elastomeric matrices and NLC droplets encapsulated within elastomeric matrices is expected to determine internal NLC director configurations; however, direct observation of molecular alignment at such buried droplet-elastomer interfaces remains inaccessible by conventional techniques. In this study, a planar sandwich-shaped cell consisting of polydimethylsiloxane (PDMS) layer was employed as an experimentally accessible model system to investigate the interfacial alignment behaviour of NLC molecules. PDMS films were assembled into sandwich cells, and NLCs with different terminal groups were injected. Polarised optical microscopy revealed that fluorine-based NLCs preferentially exhibit planar alignment on untreated PDMS surfaces, whereas cyano-based NLCs tend to align vertically. To elucidate the origin of this contrast, the PDMS surface was modified by plasma treatment and annealing treatments, and the resulting changes in surface energy and surface topology were characterised using contact angle measurements and atomic force microscopy. It was found that an increase in the polar component of the PDMS surface energy induces a transition from vertical to planar alignment, even for NLCs that originally favour vertical orientation. These results indicate that the orientation of NLC at the PDMS interface is governed by the surface energy.

We attempted to elucidate the factor determining the orientation of precipitated crystals composed of C8-BTBT grown in planar-aligned LC as the solvent. The high surface energy of the oxygen-plasma treated alignment films led to the partly-ordered-structure, with the crystalline b-axis (pi-stacking direction among C8-BTBT molecules) oriented along the substrate normal. Also, we found that chemical composition or functional group on the alignment film surface, rather than surface topology of its films, was dominant for molecular orientation of C8-BTBT in LC solvent. These results may contribute significantly to improving the degree of freedom in the device design using small-molecule organic semiconductors.

Perovskite materials are widely used as promising light absorption materials for perovskite solar cells. Poor film morphology, with crystal defects and small grain sizes, significantly impacts their performance and stability, causing charge recombination and suboptimal optoelectronic properties. To address these challenges, we incorporate five ionic liquids (ILs) for defect passivation in methylammonium lead iodide (MAPbI(3)) perovskite compositions. All ILs share the same imidazolium cation but vary in halide anions. Considering the electronegativity trend of halide anions (F > Cl > Br > I), we expect that ILs could interact with the perovskite material, enhancing its morphology and crystal stability. Furthermore, the imidazolium of ILs is expected to form coordinate covalent bonds with under-coordinated Pb. This study systematically investigates the influence of ionic liquid (IL) incorporation on the crystallinity, morphology, and optoelectronic properties of perovskite films using a range of techniques, thereby achieving defect passivation. Notably, the most exceptional results are obtained by adding 10 % 1-Butyl-3-methylimidazolium iodide (BMIM[I]), which demonstrates substantial grain growth (885 nm), maximum film coverage (98.74 %), a smoother morphology, maximum crystallite size (69.97 nm) and the highest UV absorption retention after 50 days under dark ambient conditions (75 % relative humidity). FTIR confirms the interaction between IL halide-based anions and MAPbI(3). XRD analysis indicates overall higher crystallinity and complete conversion of PbI2 to perovskite. UV-Vis results show enhanced absorption with a little change in the bandgap for all ILs. Photoluminescence (PL) analysis shows that BMIM[I]-treated films exhibit the highest PL intensity, indicating reduced defect-assisted recombination.

The slit coater method is an excellent liquid crystal (LC) alignment control technique that can order the LC alignment even on plastic substrates without pre-forming optional LC alignment films. However, controlling an arbitrary pretilt angle is still one of the issues. To elucidate the essence of the mechanism of the alignment transition from the planer to vertical alignment by UV polymerization, an in-liquid atomic force microscope was introduced. As a result, it was deduced that the LC alignment transition is induced by the realignment of mesogenic groups rather than surface topological change.

In this study, intending to develop light-functionalized films for agricultural use, we proposed a thin film that combines molecular orientation control and optical functionality of organic fluorescent dyes using the guest-host effect, and evaluated thin films formed on hydrophilic-treated polyester films using a slit coating method. Polarized optical microscopy observation and absorption spectrum measurement confirmed that liquid crystal molecules and red fluorescent dye (Solvent Red 197) were uniformly and parallelly aligned with respect to the substrate surface, yielding an external quantum efficiency of 12.28%. Furthermore, in a three-layer structure sandwiched between a polarizer and a quarter-wave plate, we demonstrated that left-handed elliptical polarization can be generated in the 600-700 nm wavelength range while wavelength converting green light in the 500-600 nm range to red fluorescence. These results are expected to contribute significantly to applications in solar conversion films for agricultural use.

It is essential to estimate the surface polar anchoring energy in order to discuss the interfacial orientation of ferroelectric nematic liquid crystals. In this study, we accurately estimated the twist angle of a pi -twist cell with an antiparallel rubbing manner, by means of renormalized transmission spectroscopic ellipsometry, which has a great deal of experience in measuring the twist angle of ordinary nematic liquid crystals. We also succeeded in estimating the reduced polar anchoring energy from the essential equation derived from the simplified torque balance equation. It is assumed that the reduced surface polar anchoring energy is on the order of 102.

The huge dielectric constant of ferroelectric nematic liquid crystals (FNLCs) seems to bring about a difficulty of molecular alignment control in exchange for a potential device application. To obtain a satisfactory level of uniform molecular alignment, it is essential to understand how the molecules near the alignment surface are anchored. In this study, bulk molecular alignment with an anti-parallel rubbing manner, which has not yet been investigated extensively, is explained using a conventional torque balance model introducing a polar anchoring function, and it is shown that the disappearance of the bulk twist alignment with decreasing cell thickness can be explained self-consistently. To validate this estimation for a room-temperature FNLC substance, the Brewster angle reflection method was attempted to confirm the surface director’s deviation from the rubbing direction caused by the polar surface anchoring.

The precise observation of a solid-liquid interface by means of frequency modulation atomic force microscopy (FM-AFM) was performed, demonstrating its applicability to a study on lead acid batteries using an electrochemical test cell for in-liquid FM-AFM embedded with a specialized cantilever holder. The consistency and reproducibility of each surface profile observed via amplitude modulation AFM and FM-AFM were verified properly in a strong acidic electrolyte. In terms of FM-AFM, the ability to observe remarkable changes in the force mapping is the most beneficial, especially near the negative electrode surface. The localization of lignosulfonate (LS) added into the electrolyte as an expander could be visualized since this characteristic force mapping was captured when LS was added to electrolyte.

In-situ amplitude-modulated atomic force microscopy observation was performed to clarify the process of lead sulfate crystal growth on the negative electrode surface of lead-acid batteries. At the peak of the discharge current in response to the oxidation reaction in cyclic voltammetry measurement, it was confirmed that crystals of several hundred nm, which are regarded to be lead sulfate, were thriving on the surface. After this process, when extinct the discharge current the gradual growth of the lead sulfate crystals observed continuously. From these results, it was found that the oxidation reaction (discharge) causes crystal growth in a two-step process on the negative electrode surface of the lead-acid battery.

Improvement of the flexoelectric coefficients estimating procedure by means of the transmission phase difference measurement was demonstrated. It was found that the sign of the sum of two flexoelectric coefficients for splay and bend deformation can be determined from the DC applied voltage dependence curve of the phase difference for obliquely incident light. The value of the sum of two flexoelectric coefficient was evaluated by means of symmetric oblique incident transmission ellipsometry (SOITE), and the several pC/m are recognizable by numerical fitting. Subtraction of two flexoelectric coefficients was also estimated with normal incidence measurement under DC applied voltage. From these three step evaluations, two flexoelectric coefficient with accuracy of several pC/m was confirmed for seven of nematic liquid crystals.