We have previously reported the chiral photomechanical behavior of azobenzene-based photochromic molecular glass particles fixed in agar gel.  That is, when their particles were irradiated with polarized 488 nm laser beam, they elongated in the direction parallel to the polarization direction of the incident laser beam accompanied with undulatory motion.  And the resulting photo-elongated particles took on a left-handed rather than right-handed helical structure at the ends of the particles.  In the present study, such chiral photomechanical behavior was also found in hydroxypropyl cellulose hydrogel, suggesting that the chiral photomechanical behaviors were the general phenomena of the azobenzene-based molecular glasses observed in chiral natural polymer-based hydrogels.  Asymmetric viscoelasticity of the surrounding chiral hydrogels seems to play a role in causing such chiral photomechanical behaviors.

Rare-earth doped ceramics nanoparticles are promising near-infrared fluorescent emitters for ratiometric nanothermometry in biological system. This study investigated the use of polypentaerythritol tetraacrylate as a coating of β-NaYF₄:Yb³⁺,Ho³⁺,Er³⁺ nanoparticles to suppress luminescence quenching in water. It was found that upconversion emission from the particles facilitated photopolymerization of pentaerythritol tetraacrylate, forming roughly 10-nm thick shells on the particle surfaces. Temperature dependence of luminescence intensity ratio was evaluated and shows an increase of Ho³⁺ emission at 1200 nm by the polymer coating.

Minuscule water droplets have been extensively used for drug screening. Smaller droplet volumes accelerate the development process and reduce costs. These minuscule droplets, with volumes ranging from a few femtoliters to several hundred microliters, are also employed in applications such as inkjet printing and femtoreactors. Owing to the continuous increase in the demand for precisely controlled small-volume droplets, we developed a film capable of arranging such droplets in a regular pattern, inspired by the surface structures of tenebrionid beetles and moth eyes. Tenebrionid beetles are known for their ability to collect water from fog through regions of contrasting wettabilities, and the nanostructure of the moth eyes enhances surface wettability. In our method, hydrophilic regions are first patterned onto a moth-eye-structured surface via photolithography. Then, the hydrophilic regions are separated using a hydrophobic resin via UV nanoimprint lithography (UV-NIL). This process yielded a film featuring a hydrophobic moth-eye surface with partially hydrophilic moth-eye regions. The resulting wettability contrast enables the alignment of miniscule water droplets on the film.

Ruddlesden-Popper (RP) Sn-based perovskite solar cells (PSCs) have emerged as an alternative to Pb-based PSCs because of their reduced environmental impact, and superior stability among Sn-based PSCs. However, the charge diffusion mechanisms remain insufficiently understood despite their critical role in device performance. In this study, we employ electron spin resonance (ESR) spectroscopy to elucidate the charge diffusion mechanism in ITO/PEDOT:PSS/(BA_0.5PEA_0.5)₂FA₃Sn₄I₁₃/PC₆₁BM/PDINO/Ag PSCs. Under illumination, no significant charge accumulation was observed in the PDINO layer. Furthermore, consistent with our previous report, electron injections from (BA_0.5PEA_0.5)₂FA₃Sn₄I₁₃ into PEDOT:PSS and open-circuit voltage improvement were observed during operando ESR measurements. These results  provide strong support for the hypothesis that electron injection from (BA_0.5PEA_0.5)₂FA₃Sn₄I₁₃ to PEDOT:PSS enhances the electron barrier at the interface, which dominantly contributes to the performance improvement during device operation. These findings provide deeper insight into the interfacial properties of RP Sn-based PSCs and may contribute to further performance optimization.

Dissolution of polymer films is a key process in lithography. However, details of the dissolution mechanism remain unclear. In this study, the dissolution kinetics of a poly(4-hydroxystyrene) (PHS) film in an ethanol/water mixture were investigated using a quartz crystal microbalance to obtain the fundamental knowledge of dissolution kinetics. As the water content (a poor solvent of PHS) increased, the intrinsic viscosity and hydrodynamic radius of the PHS molecules decreased, whereas the Huggins coefficient and developer viscosity increased. The dissolution was delayed by the increase in the developer viscosity and Huggins coefficient upon water addition, whereas the dissolution rates did not differ significantly. Two reasons are considered. First, the hydrodynamic radius decreased with the addition of water. Second, the penetration of water into the PHS film was probably faster than that of ethanol owing to the smallness of water molecule and the weak interaction between water and PHS molecules.

Bridging at the bottom of photoresist lines is a major concern in advanced lithography for manufacturing semiconductors. Although the dissolution kinetics near the bottom interfaces of resist films are believed to play a critical role in the generation of bridges, the detailed mechanism remains unknown. In this study, we investigated the dissolution kinetics of a poly(4-hydroxystyrene-co-(methyl methacrylate)-co-(methacrylic acid)) film with underlayers in three tetraalkylammonium hydroxide aqueous developers: tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. The dissolution kinetics near the bottom interface varied with underlayer and the type of developer. This phenomenon was related to the surface free energies of the underlayers and photoresist films and the surface tensions of the developers. In the well-matched case between the underlayers and the photoresists, a thick transient swelling layer containing a significant amount of developer was formed near the underlayer. In the ill-matched case, the transient swelling layer was thin.

While there has been tremendous recent progress in the deployment of full-field high numerical aperture (NA) scanners, it is generally understood that the practical viability of these amazing tools being able to achieve their full resolution capabilities in production is, to a large extent, constrained by parallel improvements in both photoresists and photomasks. In this manuscript the unique role electrons play in EUV lithography and, in particular, how these electrons impact patterning variability is addressed. New expressions for the electron image shot noise and the electron image log slope are derived, yielding a complete EUV-relevant local patterning variability equation. Using this new formulation, experimental patterning results are evaluated demonstrating the non-negligible impact of electron blur in EUV patterning with the results indicating an electron range of approximately 3 nm.

Nano- and micropatterned surfaces attract considerable research attention because they can be used in various applications such as plasmonic nanostructure. In particular, three-dimensional (3D) surfaces such as periodic structures on devices have been widely studied. Therefore, a high-throughput patterning technique that enables the use of such complex 3D surfaces in industrial applications are needed. Nanoimprint lithography (NIL) is a promising technology that represents a major breakthrough for this purpose because it is a simple patterning technique. However, the NIL process includes a direct contact process; a 3D master mold is therefore required to produce complex 3D surfaces using NIL. Electron beam lithography (EBL) is widely used to fabricate master molds for NIL applications, but obtaining a smooth 3D mold with a sub-500 nm step pattern directly is difficult with conventional EB dose modulation methods. In this study, we propose a fabrication method of NIL molds using dwell-time algorithm to obtain a smooth surface using direct 3D patterning based on EBL. Consequently, we obtained a target distribution of a 3D pattern with a two-step structure for EBL.

Cesium lead chloride (CsPbCl₃) perovskite nanocrystals (NCs) are promising nanomaterials for pure blue colour or ultraviolet light emitters. Although many NC synthesis reaction parameters influence NC size, it is not trivial to achieve high photoluminescence quantum yield (PLQY) without post-treatment. Here we demonstrate controlling CsPbCl₃ nanocuboid size and PLQY using a hot injection method without post-treatment. CsPbCl₃ nanocuboid length can be readily tuned from 4.5 nm to 12 nm by altering precursor lead ion concentration and lead to cesium ion concentration ratio, while the maximum PLQY of ~40% can be achieved for the nanocuboid whose length is about 6 nm.

The moth-eye structure is employed in biomimetics and exhibits anti-reflection properties and enhanced wettability. The moth-eye structure is lined with nanopillars and has various industrial applications requiring the prevention of light reflection from surfaces. In this study, moth-eye structures were fabricated on a photosensitive polyimide (PI) surface and used as a mold to replicate moth-eye structures by performing ultraviolet nanoimprint lithography (UV-NIL). In addition, hybrid structures were fabricated using micropatterned photosensitive PI with a moth-eye structure. Micropatterns for the photosensitive PI were fabricated using photolithography. The moth-eye structure was formed by irradiating the PI surface with an oxygen-ion beam. The reflection of the moth-eye-structured PI and the replicated moth-eye structure was 0.5% at visible-light wavelengths. A micropatterned PI mold with a moth-eye structure was also fabricated and replicated using UV-NIL. The replicated pattern retained the inverted hybrid structure.

Poly(tert-butyl methacrylate) (PtBMA) and poly(1-methyl-1-(6-methyl-7-oxabicyclo[4.1.0]hept-3-yl)ethyl methacrylate)  (PMOBH), a type of degradable polymers, which generate gaseous or volatile compounds, such as isobutene and limonene, were decomposed after ultrasound-irradiation and subsequent heating in the presence of titanium oxide (TiO₂) and a photoacid generator (PAG).  The decomposition behaviors of PtBMA or PMOBH containing TiO₂ and PAG were investigated and discussed in terms of the chemical structures of the polymers and reaction mechanism.  We believe that the degradation contributes to reduce environmental impact such as the easy recycling of composite materials.

Although the correlation between monomer conversion and residual stress in photopolymerization has been widely studied, a fully predictive numerical model grounded in a complete theoretical framework remains lacking. Residual stress accumulated during curing can significantly compromise the mechanical and dimensional stability of UV curable resin. In this study, a coupled chemo-mechanical model was developed to predict residual stress evolution in UV-curable systems, incorporating key subprocesses such as polymerization kinetic, volume shrinkage, gelation, and residual stress development. Kinetic parameters were optimized using a genetic algorithm (GA) based on experimental data, and validated through real-time FT-IR and photo-rheometer. Without empirical fitting, the model accurately predicts stress evolution under specific irradiation conditions where the system approaches quasi-equilibrium. However, it fails to capture stress behavior in early non-equilibrium or post-vitrification elastic-dominated stages. Incorporating empirical equation improves global prediction accuracy, especially in the mid-to-late curing stages, but increase deviation at low intensity and short irradiation times. These results highlight the trade-off between general applicability and local accuracy in stress modeling.

Photocurable polymer composites are of considerable interest for the fabrication of photonic structures. In this work, a nanocomposite based on acrylate monomers filled with arsenic sulfide and gold nanoparticles was investigated. This material was also employed for holographic recording of diffraction gratings. Since holographic recording involves two processes – polymerization and nanoparticle diffusion – it is crucial to study the influence of nanoparticles on the kinetics of the polymerization process. It was found that the introduction of either chalcogenide nanoparticles or gold nanoparticles into the composition inhibits polymerization. However, their simultaneous incorporation in certain ratios leads to an increase in the conversion degree and enhances the diffraction efficiency of the gratings. Moreover, the ratio between the photoinitiator and nanoparticles plays a key role, as it affects both the polymerization rate and nanoparticle diffusion, thereby determining the diffraction efficiency of the gratings.

The Multi-Trigger Resist (MTR), a novel negative tone photoresist, shows significant potential for extreme ultraviolet (EUV) lithography, offering lower dose to size (DtS) requirements compared to chemically amplified resists (CARs) and metal oxide resists (MORs). This research develops and validates a stochastic model of the Multi-Trigger Resist process. The model accounts for statistical variations in photon distribution, secondary electron generation, and molecular distribution within the photoresist. First simulation results show a good reproduction of experimental data. Current studies refine the existing MTR model with updated calibration data and expands the analysis to better understand roughness effects. Simulation results closely reproduce experimental trends, capturing critical dimension (CD) and line-edge roughness (LER) behaviors. An exploratory study of PAG loading reveals that increasing PAG concentration improves sensitivity and reduces roughness up to an intermediate optimum, while under-loading raises dose requirements and produces a LER upturn, most pronounced at 28-nm pitch. These results define a practical PAG loading window that balances DtS and LER performance, providing guidance for future MTR formulation and process optimization.

Developing high performance UV-LED excited photoinitiators is one of research focuses in the field of photopolymerization. Thioxanthone derivatives, which reveal outstanding absorptions in the UV-Vis spectra, have potential excited by UV light source. In this article, two novel thioxanthone-based photoinitiators, 9-oxo-9H-thioxanthen-2-yl 4-(dimethylamino)benzoate (TXOH-DB) and 1-chloro-9-oxo-9H-thioxanthen-4-yl 4-(dimethylamino)benzoate (TXCl-DB), were designed and synthesized, and their structure has been confirmed by FT-IR and ¹H NMR. The UV-vis spectra showed that these two photoinitiators appeared redshift compare with TX, and the UV absorption ability of TXCl-DB was stronger than TX. Steady state photolysis experiments and photopolymerization experiments indicated that TXOH-DB and TXCl-DB were one-component photoinitiators and could successfully initiate 2-hydroxyethyl acrylate (HEA), 1,6-hexanediol diacrylate (HDDA) and Trimethylolpropane triacrylate (TMPTA) under UV-LED @395 nm (10 W) without the presence of co-initiatar. In addition, TXOH-DB and TXCl-DB have better migration stability and have the potential for use in UV curing systems, especially in food packaging and biomedical applications.

The lift-off process offers a reliable approach for achieving designed patterns in semiconductor manufacturing. This study investigates the application of a negative photoresist-based lift-off process for pattern transfer of a 380 nm-thick Cr/Au layer. The underlying mechanism and critical parameters of the lithography process, such as soft bake temperature, exposure energy, exposure gap, and post-exposure bake (PEB) temperature, were investigated in detail. Undercut morphology, undercut width, post-development defects, and photoresist morphology after metal evaporation were characterized. Experimental results show that these parameters critically affect the exposure process by controlling the concentration and distribution of photo-acid generators in the photoresist, thereby defining the final undercut morphology. Furthermore, the study outlines a methodology for varying process parameters to define the process window and identify optimal conditions. It was confirmed that the morphology and width of the developed undercut are crucial to a successful lift-off, and an undercut width of at least 3.00 µm is required to ensure satisfactory outcomes.