Abstract We report the assembly of binary nanoparticle superlattices (BNSLs) composed of amphiphilic block copolymers and colloidal silica, driven by a balance between complementary associative and self-repulsive interactions. In aqueous media, spherical polystyrene-block-poly(ethylene glycol) (PS-b-PEG) micelles co-assemble with similarly sized silica nanoparticles (NPs) via hydrogen bonding between the PEG corona and the silica surface. Concurrently, electrostatic repulsions between the silica NPs regulate coordination numbers to direct long-range structural order. By tuning the pH and ionic strength, we modulate these attractive and repulsive forces to access both NaCl- and CsCl-type lattice symmetries from a single pair of building blocks. This organic–inorganic hybrid platform provides a rare example of BNSL assembly achieved without specific or directional ligands, while maintaining high structural tunability governed by the intrinsic properties of the polymer micelles and silica NPs.

Ferroelectric field-effect transistors offer a potential for its important role in integrated memory and computing systems, and research on them is actively ongoing. In this study, we investigated the ferroelectric properties of $\mathrm{Pb}(\mathrm{Z}{\mathrm{r}}_{0.7}\mathrm{T}{\mathrm{i}}_{0.3}){\mathrm{O}}_{3}$, which is lattice matched with the La-doped high mobility perovskite oxide semiconductor $\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x}\mathrm{Sn}{\mathrm{O}}_{3}$. Growth of the $r$ phase in epitaxial $\mathrm{Pb}(\mathrm{Z}{\mathrm{r}}_{0.7}\mathrm{T}{\mathrm{i}}_{0.3}){\mathrm{O}}_{3}$ on $\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x}\mathrm{Sn}{\mathrm{O}}_{3}$ was confirmed and its basic ferroelectric and dielectric properties were studied by polarization-electric and capacitance-voltage measurement. We then studied the field effect of $\mathrm{Pb}(\mathrm{Z}{\mathrm{r}}_{0.7}\mathrm{T}{\mathrm{i}}_{0.3}){\mathrm{O}}_{3}$ on the electrical properties of $\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x}\mathrm{Sn}{\mathrm{O}}_{3}$ as we vary the La doping concentration. We find that the field effect of $\mathrm{Pb}(\mathrm{Z}{\mathrm{r}}_{0.7}\mathrm{T}{\mathrm{i}}_{0.3}){\mathrm{O}}_{3}$ on $\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{L}{\mathrm{a}}_{x}\mathrm{Sn}{\mathrm{O}}_{3}$ is determined by competition between its ferroelectric and dielectric properties, depending on the La doping concentration. In high La doping rates, the field effect is dominated by the ferroelectric switching while in lower La doping rates, the effect is mainly by dielectric response as the depolarization field in the depleted layer weakens the ferroelectric effect. As per the width and direction of the hysteresis, it is also controlled by the competition between the counterclockwise ferroelectric response and the clockwise dielectric response due to the trapped charges near the interface. This study offers insights into optimizing the field effect by understanding the complex interplay between ferroelectric materials and low carrier density semiconductors.

High sulfur content polymeric materials, known for their intriguing properties such as high refractive indices and high electrochemical capacities, have garnered significant interest in recent years for their applications in optics, antifouling surfaces, triboelectrics, and electrochemistry. Despite the high interest, most high sulfur-content polymers reported to date are either bulk materials or thin films, and there is a general lack of research into sulfur-rich polymer colloids. Water-dispersed, sulfur-rich particles are anticipated to broaden the range of applications for sulfur-containing materials. In this study, the preparation and size control parameters are presented of an aqueous dispersion of sulfur-rich polymers with the sulfur content of dispersed particles exceeding 75 wt%. Employing polymeric stabilizers with varying hydrophilic-lipophilic balance (HLB), along with changing the rank of inorganic polysulfides, allow for the control of particle size in the range of 360 nm - 1.8 mu m. The sulfur-rich colloid demonstrates antioxidant properties in water, demonstrating the potential for the use of sulfur-rich polymeric materials readily removable, heterogeneous radical scavengers. This study presents the synthesis of polysulfide particles in diverse sizes utilizing phase transfer catalysts and polymeric stabilizers, contrasting with prior research. Particularly notable is the one-step growth of polymer particle size by more than 1 mu m. The resultant polysulfide segments exhibit size-dependent antioxidant effects, suggesting potential application as radical scavengers. image

A unique organic-inorganic hybrid network composed of inorganic nanocores (ranging from semiconductors to metallic ones) interconnected through organic molecules can be produced by crosslinking the organic ligands of colloidal inorganic nanocrystals in assemblies. This work reports that this network, which is conventionally considered an inorganic film, can swell when exposed to a solvent because of the interaction between the solvent and the organic linkage within the network. Intriguingly, this work discovers that drying the solvent of the swollen organic-inorganic hybrid network can significantly affect the morphology owing to the swelling-induced compress stress, which is widely observed in various organic network systems. This work studies the surface instability of crosslinked organic-inorganic hybrid networks swollen by various organic solvents, which led to buckling delamination. Specifically, this work investigates the effects of the i) solvent-network interaction, ii) crosslinking density of the network, and iii) thickness of the film on the delamination behavior of the crosslinked network.

Auger recombination (AR), whereby the electron-hole recombination energy is transferred to a third charge carrier, prevails in nanocrystal quantum dots (QDs) and governs the performance of QD-based devices including light-emitting diodes and lasers. Thus, precise AR evaluation of QDs is essential for understanding and improving the characteristics of such applications. So far, conventional charging approaches, such as the stir-versus-static method, photochemistry, or electrochemistry, have been able to assess the AR decay rate of either positively (two holes and one electron, X+) or negatively (one hole and two electrons, X-) charged excitons, and the decay dynamics of the other type of charged exciton is presumably estimated by the superposition principle of the biexciton Auger process. Herein, we demonstrate an opto-electrical method that enables us to precisely assess AR rates of X+ and X- in core/shell heterostructured QDs. Specifically, we devise electron-only devices and hole-only devices to inject extra charge carriers into QDs without unwanted side reactions or degradation of QDs and probe AR characteristics of these charged QDs via time-resolved photoluminescence measurements. We find that AR rates of charged excitons, both X+ and X-, gained from the present method agree well with those attained from conventional approaches and the superposition principle, corroborating the validity of the present approach. This present method permits us to comprehend multicarrier dynamics in QDs, prompting the use of QDs in light-emitting diodes and laser devices based on QDs.

Colloidal Ag(In,Ga)S 2 nanocrystals (AIGS NCs) with the band gap tunability by their size and composition within visible range have garnered surging interest. High absorption cross-section and narrow emission linewidth of AIGS NCs make them ideally suited to address the challenges of Cd-free NCs in wide-ranging photonic applications. However, AIGS NCs have shown relatively underwhelming photoluminescence quantum yield (PL QY) to date, primarily because coherent heteroepitaxy has not been realized. Here, we report the heteroepitaxy for AIGS-AgGaS 2 (AIGS-AGS) core-shell NCs bearing near-unity PL QYs in almost full visible range (460 to 620 nm) and enhanced photochemical stability. Key to the successful growth of AIGS-AGS NCs is the use of the Ag-S-Ga(OA) 2 complex, which complements the reactivities among cations for both homogeneous AIGS cores in various compositions and uniform AGS shell growth. The heteroepitaxy between AIGS and AGS results in the Type I heterojunction that effectively confines charge carriers within the emissive core without optically active interfacial defects. AIGS-AGS NCs show higher extinction coefficient and narrower spectral linewidth compared to state-of-the-art heavy metal-free NCs, prompting their immediate use in practicable applications including displays and luminescent solar concentrators (LSCs).

Recent advances in fabricating stretchable and transparent electrodes have led to various techniques for establishing next-generation form-factor optoelectronic devices. Wavy Ag nanowire networks with large curvature radii are promising platforms as stretchable and transparent electrodes due to their high electrical conductivity and stretchability even at very high transparency. However, there are disadvantages such as intrinsic nonregular conductivity, large surface roughness, and nanowire oxidation in air. Here, we introduce electrically synergistic but mechanically independent composite electrodes by sequentially introducing conducting polymers and ionic liquids into the wavy Ag nanowire network to maintain the superior performance of the stretchable transparent electrode while ensuring overall conductivity, lower roughness, and long-term stability. In particular, plenty of ionic liquids can be incorporated into the uniformly coated conducting polymer so that the elastic modulus can be significantly lowered and sliding can occur at the nanowire interface, thereby obtaining the high mechanical stretchability of the composite electrode. Finally, as a result of applying the composite film as the stretchable transparent electrode of stretchable organic solar cells, the organic solar cell exhibits a high power conversion efficiency of 11.3% and 89% compared to the initial efficiency even at 20% tensile strain, demonstrating excellent stretching stability.

Mesoporous microparticles have the potential to be used in various fields, such as energy generation, sensing, and the environmental field. Recently, the process of making homogeneous microparticles in an economical and environmentally friendly way has gained much attention. Herein, rectangular mesoporous microblocks of various designs are produced by manipulating the fragmentation of colloidal films consisting of micropyramids while controlling the notch angles of pyramidal edges. During calcination of the colloidal films, cracks are generated in the valleys of micropyramids acting as notches, and the angle of notches can be controlled by the prepattern underneath the micropyramids. By changing the location of notches with sharp angles, the shape of microblocks can be controlled with excellent uniformity. After detaching the microblocks from substrates, mesoporous microparticles of various sizes with multiple functions are easily produced. This study demonstrates anti-counterfeiting functions by encoding the rotation angles of rectangular microblocks of various sizes. In addition, the mesoporous microparticles can be utilized for separating desired chemicals mixed with chemicals of different charges. The method of fabricating size-tunable functionalized mesoporous microblocks can be a platform technology to prepare special films and catalysts and for environmental applications.

High sulfur content polymers (HSCPs) are regarded as promising materials for infrared (IR) optics, especially the long-wave IR range, due to intrinsic properties of sulfur, but the poor thermal stability of HSCPs limits their reliable utilization in wider IR applications. We herein present a new HSCP, poly(sulfur-co-hexavinyl disiloxane) (pSHVDS), prepared directly from elemental sulfur through sulfur vapor chemical deposition (sCVD). By employing hexavinyl disiloxane (HVDS) comonomer with high functionality (f = 12) and weak absorption in the IR range, despite the poor compatibility between sulfur and HVDS, the sCVD process enables the preparation of highly cross-linked HSCP with 68 wt % sulfur. Furthermore, the combination of high refractive index (RI) of 1.842, high glass transition temperature (T-g ) of 151 degree celsius, and high transparency in visible, mid- and long-wave IR range is achieved successfully, which is an unprecedentedly unique property compared to HSCPs reported to date. These favorable properties of pSHVDS render the material ideal for antireflection applications in IR optics, and conformal pSHVDS coatings on germanium IR lenses significantly improved the transmittance in mid- and long-wave IR regions. The developed polymer will lead the new possibility for polymer based optical devices, especially in the IR range.

We herein report the preparation of high refractive index polymers (HRIPs) with enhanced thermal stability from the copolymerization of S-8 and divinylbenzene (DVB) in a single step through sulfur chemical vapor deposition (sCVD). Varying the process temperature in sCVD allowed for the preparation of a series of high sulfur content polymers which, in comparison to previously reported sulfur-derived polymers with similar compositions, displayed significantly enhanced solvent resistance, glass transition temperature (T-g), and thermal stability attributed to the absence of long polysulfide chains in the polymer matrix. The resulting HRIP films displayed high transmittance over the entire visible range while showing an unprecedentedly high T-g of 110 C, which is one of the highest to date among HRIPs with refractive index (RI) exceeding 1.8 reported to date. With the combination of ultrahigh (> 1.8) RI, thermal stability, and high T-g, the HRIPs can serve as compelling materials for advanced optical applications.

Maximizing the energy density of a lithium-ion battery cell by increasing the silicon content in the silicon-graphite (Si-Gr) composite anode is an ongoing research topic that is receiving much attention. However, the paradoxical surface characteristics of Si and Gr make it challenging to uniformly distribute the electrode components and maintain their adhesion during cycling accompanied with the immense volume change of Si. Here, an amphiphilic, tightly interlocked host-guest complex binder composed of pyrene-conjugated poly(acrylic acid) (Py-PAA) and a hyperbranched gamma-cyclodextrin polymer (gamma CDp) is reported. The pyrene unit of Py-PAA not only endows enhanced affinity to the Gr surface but also serves as a guest molecule capable of interlocking with the gamma CDp host. This highly effective host-guest interaction sustains the integrity of the electrode to enable superior cycling performance and rate capability for Si-Gr electrodes with commercial-level areal capacity. This study shows that hierarchical, multifunctional supramolecular binders of two kinds can offer improved battery performance for emerging high-capacity electrodes consisting of components with different surface characteristics compared to conventional binders of a single kind.

Cracks are common in nature. Cracking is known as an irreversible and uncontrollable process. To control the cracking patterns, many researchers have proposed methods to prepare notches for stress localization on films. In this work, we investigate a method of controlling cracks by making microscale pyramid patterns that have notches between the pyramids. After preparing pyramid patterns consisting of colloidal particles with organic residue, we annealed them to induce volume shrinkage and cracking between the pyramids. We studied the effect of film thickness on cracking and the generation of rectangular fragments consisting of multiple pyramids. The area of rectangular fragments was in good agreement with the results of scaling analysis. The concept of controlling cracks by imprinting notches on a film and the relationship with the film thickness can guide the study of cracking phenomena.

A one-step bulk polymerization between elemental sulfur and allyl glycidyl ether yields epoxy cross-linked sulfur polymers with unprecedentedly high mechanical strength and rapid shape-memory performance.

ABC triblock copolymers composed of hydrophobic poly(ε-caprolactone) (PCL), zwitterionic poly(carboxybetaine methacrylate) midblock, and P(PEGMA-UPy0.15 ) containing supramolecular ureidopyrimidinone moieties, poly(ε-caprolactone-block-carboxybetaine methacrylate-block-[poly(ethylene glycol) methyl ether methacrylate-co-(α-methacryloyl-ω-(6-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)hexylcarbamoyloxy)poly(ethylene glycol))]), are investigated to achieve multifunctional antifreeze hydrogels. The PCL and P(PEGMA-UPy0.15 ) blocks induce the formation of physical network with a hierarchical nanostructure comprising hydrophobic PCL cores and supramolecular junctions, respectively. The super-hydrophilic nature of polyzwitterion midblocks and the confinement effect of the supramolecular junctions enhance the antifreeze performance, where the majority of water molecules remains supercooled below sub-zero temperature. The hydrogel relaxation characterized over a wide range of timescale reveals that the facile dynamics of the supramolecular junctions lead to the self-healing and injectability of the hydrogels. In conjunction with the biodegradable PCL cores, the antifreeze and rheological characteristics of the triblock copolymer hydrogels provide significant potential to use for cryo-preservable and bio-injectable drug storage and delivery.

Quasi-type II heterostructured nanocrystals (NCs) have been of particular interest due to their great potential for controlling the interplay of charge carriers. However, the lack of material choices for quasi-type II NCs restricts the accessible emission wavelength from red to near-infrared (NIR), which hinders their use in light-emitting applications that demand a wide range of visible colors. Herein, we demonstrate a new class of quasi-type II nanoemitters formulated in ZnSe/ZnSe 1- X Te X /ZnSe seed/spherical quantum well/shell heterostructures (SQWs) whose emission wavelength ranges from blue to orange. In a given geometry, ZnSe 1- X Te X emissive layers grown between the ZnSe seed and the shell layer are strained to fit into the surrounding media, and thus, the lattice mismatch between ZnSe 1- X Te X and ZnSe is effectively alleviated. In addition, composition of the ZnSe 1- X Te X emissive layer and the dimension of the ZnSe shell layer are engineered to tailor the distribution and energy of electron and hole wave functions. Benefitting from the capabilities to tune the charge carriers on demand and to form defect-free heterojunctions, ZnSe/ZnSe 1- X Te X /ZnSe/ZnS NCs show near-unity photoluminescence quantum yield ( PL QY > 90 % ) in a broad range of emission wavelengths (peak PL from 450 nm to 600 nm). Finally, we exemplify dichromatic white NC-based light-emitting diodes (NC-LEDs) employing the mixed layer of blue- and yellow-emitting ZnSe/ZnSe 1- X Te X /ZnSe/ZnS SQW NCs.

BACKGROUND:Various cell-culture systems have been used to evaluate drug toxicity in vitro. However, factors that affect cytotoxicity outcomes in drug toxicity evaluation systems remain elusive. In this study, we used multilayered sheets of cardiac-mimetic cells, which were reprogrammed from human fibroblasts, to investigate the effects of the layer number on drug cytotoxicity outcomes.METHODS:Cell sheets of cardiac-mimetic cells were fabricated by reprogramming of human fibroblasts into cardiac-mimetic cells via coculture with cardiac cells and electric stimulation, as previously described. Double-layered cell sheets were prepared by stacking the cell sheets. The mono- and double-layered cell sheets were treated with 5-fluorouracil (5-FU), an anticancer drug, in vitro. Subsequently, apoptosis and lipid peroxidation were analyzed. Furthermore, effects of cardiac-mimetic cell density on cytotoxicity outcomes were evaluated by culturing cells in monolayer at various cell densities.RESULTS:The double-layered cell sheets exhibited lower cytotoxicity in terms of apoptosis and lipid peroxidation than the mono-layered sheets at the same 5-FU dose. In addition, the double-layered cell sheets showed better preservation of mitochondrial function and plasma membrane integrity than the monolayer sheets. The lower cytotoxicity outcomes in the double-layered cell sheets may be due to the higher intercellular interactions, as the cytotoxicity of 5-FU decreased with cell density in monolayer cultures of cardiac-mimetic cells.CONCLUSION:The layer number of cardiac-mimetic cell sheets affects drug cytotoxicity outcomes in drug toxicity tests. The in vitro cellular configuration that more closely mimics the in vivo configuration in the evaluation systems seems to exhibit lower cytotoxicity in response to drug.

The random amphiphilic copolymers containing a large fraction (35-50 mol %) of ureidopyrimidinone (UPy) that can dimerize using a quadruple hydrogen bonding were synthesized to produce antifreeze and dynamic hydrogels. Directional packing of the UPy-UPy dimers provides nanosized aggregates, and the effective gap distance between the aggregates is narrow enough to inhibit the water crystallization by the confinement effect. The characteristic dimensions such as the aggregate size and gap distance depend on the polymer concentration and the UPy fraction in the polymers. Furthermore, the temperature-dependent dynamics of UPy allows the hydrogels to form the frozen structure at a lower temperature, while the injectability and self-healing property were achieved at room temperature. The antifreeze hydrogels also exhibit negligible cytotoxicity and thus expands the applicable area including the drug storage and cell cryopreservation.

High refractive index (RI) thin films are of critical importance for advanced optical devices, and the high refractive index polymers (HRIPs) constitute an interesting class of materials for high RI thin films due to low cost, good processability, light weight, and high flexibility. However, HRIPs have yet to realize their full potential in high RI thin film applications due to their relatively low RI, strong absorption in the blue light region, and limited film formation methods such as rapid vitrification. Herein, we report a development of a new HRIP thin film generated through a one-step vapor-phase process, termed sulfur chemical vapor deposition (sCVD), using elemental sulfur and divinyl benzene. The developed poly(sulfur-co-divinyl benzene) (pSDVB-sCVD) film exhibited RI (measured at 632.8 nm) exceeding 1.97, one of the highest RIs among polymers without metallic elements reported to date. Because the sCVD utilized vaporized sulfur with a unique sulfur-cracking step, formation of long polysulfide chains was suppressed efficiently, while high sulfur content as high as 85 wt % could be achieved with no apparent phase separation. Unlike most of inorganic high RI materials, pSDVB-sCVD was highly transparent in the entire visible range and showed extremely low birefringence of 10 × 10-4. The HRIP thin film with unprecedentedly high RI, together with outstanding transparency and low birefringence, will serve as a key component in a wide range of high-end optical device applications.

It is important to specify and control factors that significantly affect the performance and stability of organic solar cells (OSCs). Bulk heterojunctions (BHJs) prepared by spin-coating donor/acceptor mixtures form vertically and laterally complex nanostructures, making them difficult to specify and control. Herein, various solvent-dissolved PTB7-th/PC70BM-based sequentially processed OSCs are demonstrated and their thin-film properties in terms of interfacial crystallinity are compared. The crystallinity of the donor/acceptor interfaces and PC70BM over-layers is effectively controlled by varying the boiling points of the PTB7-th solvents in sequential processes. It is found that the structures of the PTB7-th layers formed by solvents with lower boiling points, as well as the PC70BM over-layers, have a higher degree of crystallinity, consequently improving the performance to a degree resembling that of BHJ cells. In addition, sequentially processed samples show much higher thermal stability than BHJ cells, which constitute a nano-blend of donor and acceptor materials. When compared with BHJ cells, whose power conversion efficiency deteriorates within the initial 5 h of thermal treatment, all sequentially processed devices deposited by solvents with different boiling points show significant thermal stability. This work provides comprehensive insight into the interfacial crystallinity of sequentially processed OSCs in terms of efficiency and stability.

Due to the exceptional theoretical energy density and low cost of elemental sulfur, lithium–sulfur (Li–S) batteries are spotlighted as promising post‐lithium‐ion batteries. Despite these advantages, the performance of Li–S batteries would need to be improved further for their wide dissemination in practical applications. Here, cobalt(II)‐centered fluorinated phthalocyanine, namely, F‐Co(II)Pc, is reported as a multi‐functional component for sulfur cathodes with the following benefits: 1) enhanced conversion kinetics as a result of the catalytic effect of the cobalt(II) center, 2) efficient sulfur linkage via the fluorine functionality, which undergoes a nucleophilic aromatic substitution (SNAr) reaction, 3) suppression of the shuttling issue by the nitrogen atoms because of their strong affinity with polysulfides, and 4) the necessary aromaticity to engage in π–π interaction with reduced graphene oxide for electrical conductivity. The resulting electrode has promising electrochemical properties, such as sustainable cycling for 700 cycles and robust operation with a sulfur loading of 12 mgsulfur cm−2, unveiling the promising nature of phthalocyanine and its related molecular families for advanced Li–S batteries.