Highly Efficient Self-Encapsulated Flexible Semitransparent Perovskite Solar Cells via Bifacial Cation Exchange.

Flexible semitransparent perovskite solar cells (ST-PSCs) have great potential for use in high-density energy systems, such as building or vehicle integrated photovoltaics, considering the great features of PSC devices, including high performance, light weight, thin-film processability, and high near-infrared transmittance. Despite numerous efforts toward achieving efficiency and flexibility in ST-PSCs, the realization of high-performance and operational stability in ST-PSCs still require further development. Herein, we demonstrated the development of highly efficient, stable, and flexible ST-PSCs using polyimide-integrated graphene electrodes via a lamination-assisted bifacial cation exchange strategy. A high-quality perovskite layer was obtained through the cation exchange reaction using the lamination process, and ST-PSCs with 15.1% efficiency were developed. The proposed ST-PSC device also demonstrated excellent operational stability, mechanical durability, and moisture stability owing to the chemically inert and mechanically robust graphene electrodes. This study provides an effective strategy for developing highly functional ST-perovskite optoelectronic devices with high-performance and long-term operational stability.

Highly Elastic and Corrosion-Resistive Metallic Glass Thin Films for Flexible Encapsulation.

Ternary CuZrTi metallic glass thin films synthesized by sputtering are suggested as highly flexible and corrosion-resistant encapsulation materials. Unlike nanocrystalline Cu and binary CuZr metallic glass thin films, the ternary CuZrTi metallic glass thin films retain amorphous structure and do not oxidize even after 1000 h in an accelerated harsh environment at 85 °C with 85% relative humidity. The encapsulation performance of 260 nm thick ternary CuZrTi metallic glass is maintained even after 1000 bending cycles at a 3% tensile strain, corresponding to 70% of the elastic deformation limit, according to the results of a uniaxial tensile test. Because of the enhanced mechanical flexibility and reliability of the ternary CuZrTi metallic glass thin films, they have been applied to flexible organic solar cells as an encapsulation material.

Amorphous Alumina Film Robust under Cyclic Deformation: a Highly Impermeable and a Highly Flexible Encapsulation Material.

The lack of highly impermeable and highly flexible encapsulation materials is slowing the development of flexible organic solar cells. Here, a transparent and low-temperature synthetic alumina single layer is suggested as a highly impermeable and a highly flexible encapsulation material for organic solar cells. While the water vapor transmission rate (WVTR) is maintained up to 100,000 bending cycles for a 25 mm bending radius (corresponding to 8.1% of the elastic deformation limit), as measured by in situ tensile testing with free-standing 50 nm-thick alumina films, the WVTR degraded gradually depending on the bending radius and bending cycles for bending radii less than 25 mm. The degradation of the WVTR in cyclic deformation within the elastic deformation limit is investigated, and it is found to be due to the formation of pinholes by a bond-switching mechanism. Also, encapsulated organic solar cells with alumina films are found to maintain 80% of initial efficiency for 2 weeks even after cyclic bending with a 4 mm bending radius.

Suppressed Interdiffusion and Degradation in Flexible and Transparent Metal Electrode-Based Perovskite Solar Cells with a Graphene Interlayer.

Metal-based transparent conductive electrodes (TCEs) are attractive candidates for application in indium tin oxide (ITO)-free solar cells due to their excellent electrical conductivity and cost effectiveness. In perovskite solar cells (PSCs), metal-induced degradation with the perovskite layer leads to various detrimental effects, deteriorating the device performance and stability. Here, we introduce a novel flexible hybrid TCE consisting of a Cu grid-embedded polyimide film and a graphene capping layer, named GCEP, which exhibits excellent mechanical and chemical stability as well as desirable optoelectrical properties. We demonstrated the critical role of graphene as a protection layer to prevent metal-induced degradation and halide diffusion between the electrode and perovskite layer; the performance of the flexible PSCs fabricated with GCEP was comparable to that of their rigid ITO-based counterparts and also exhibited outstanding mechanical and chemical stability. This work provides an effective strategy to design mechanically and chemically robust ITO-free metal-assisted TCE platforms in PSCs.

Ultrasensitive Plasmon-Free Surface-Enhanced Raman Spectroscopy with Femtomolar Detection Limit from 2D van der Waals Heterostructure.

Two-dimensional (2D) materials have been promoted as an ideal platform for surface-enhanced Raman spectroscopy (SERS), as they mitigate the drawbacks of noble metal-based SERS substrates. However, the inferior limit of detection has limited the practical applicability of 2D material-based SERS substrates. Here, we synthesize uniform large-area ReOxSy thin films via solution-phase deposition without post-treatments and demonstrate a graphene/ReOxSy vertical heterostructure as an ultrasensitive SERS platform. The electronic structure of ReOxSy can be modulated by changing the oxygen concentration in the lattice structure, obtaining efficient complementary resonance effects between ReOxSy and the probe molecule. In addition, the oxygen atoms in the ReOxSy lattice generate a dipole moment on the thin-film surface, which increases the electron transition probability. These synergistic effects outstandingly enhance the Raman effect in the ReOxSy thin film. When ReOxSy forms a vertical heterostructure on a graphene as the SERS substrate, the enhanced charge-transfer and exciton resonances improve the limit of detection to the femtomolar level, while achieving remarkable flexibility, reproducibility, and operational stability. Our results provide important insights into 2D material-based ultrasensitive SERS based on chemical mechanisms.

Dieckol, a Component of Ecklonia cava, Suppresses the Production of MDC/CCL22 via Down-Regulating STAT1 Pathway in Interferon-γ Stimulated HaCaT Human Keratinocytes.

Macrophage-derived chemokine, C-C motif chemokine 22 (MDC/CCL22), is one of the inflammatory chemokines that controls the movement of monocytes, monocyte-derived dendritic cells, and natural killer cells. Serum and skin MDC/CCL22 levels are elevated in atopic dermatitis, which suggests that the chemokines produced from keratinocytes are responsible for attracting inflammatory lymphocytes to the skin. A major signaling pathway in the interferon-γ (IFN-γ)-stimulated inflammation response involves the signal transducers and activators of transcription 1 (STAT1). In the present study, we investigated the anti-inflammatory effect of dieckol and its possible action mechanisms in the category of skin inflammation including atopic dermatitis. Dieckol inhibited MDC/CCL22 production induced by IFN-γ (10 ng/mL) in a dose dependent manner. Dieckol (5 and 10 µM) suppressed the phosphorylation and the nuclear translocation of STAT1. These results suggest that dieckol exhibits anti-inflammatory effect via the down-regulation of STAT1 activation.

Diphlorethohydroxycarmalol inhibits interleukin-6 production by regulating NF-κB, STAT5 and SOCS1 in lipopolysaccharide-stimulated RAW264.7 cells.

Diphlorethohydroxycarmalol (DPHC) is a phlorotannin compound isolated from Ishige okamuarae, a brown alga. This study was conducted to investigate the anti-inflammatory effect and action mechanism of DPHC in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that DPHC strongly reduces the production of interleukin 6 (IL-6), but not that of tumor necrosis factor-alpha (TNF-α) induced by LPS. DPHC (12.5 and 100 µM) suppressed the phosphorylation and the nuclear translocation of NF-kappaB (NF-κB), a central signaling molecule in the inflammation process induced by LPS. The suppressor of cytokine signaling 1 (SOCS1) is a negative feedback regulator of Janus kinase (Jak)-signal transducer and activator of transcription (STAT) signaling. In this study, DPHC inhibited STAT5 expression and upregulated that of SOCS1 at a concentration of 100 µM. Furthermore, N-tosyl-l-phenylalanine chloromethyl ketone (TPCK) (a specific NF-κB inhibitor) and JI (a specific Jak2 inhibitor) reduced the production of IL-6, but not that of tumor necrosis factor-alpha (TNF-α) in LPS-stimulated RAW 264.7 macrophages. These findings demonstrate that DPHC inhibits IL-6 production via the downregulation of NF-κB and Jak2-STAT5 pathway and upregulation of SOCS1.

Docosahexaenoic Acid Alleviates Atopic Dermatitis by Generating Tregs and IL-10/TGF-ß-Modified Macrophages via a TGF-ß-Dependent Mechanism.

Regulatory T cells (Tregs) have key roles in the immune response by suppressing the differentiation and proliferation of various immune cells. The beneficial effects of docosahexaenoic acid (DHA) have been described for many diseases; however, the mechanism by which it modulates the immune system is poorly understood. Therefore, the aim of this study was to examine whether DHA suppresses allergic reactions and upregulates the generation of CD4(+)Foxp3(+) T cells. We also examined the effects of transfusing interleukin-10/transforming growth factor-ß (TGF-ß)-modified macrophages (M2 macrophages) treated with DHA into a mouse model of atopic dermatitis. Here, we show that administration of DHA upregulates the generation of TGF-ß-dependent CD4(+) forkhead box protein 3 (Foxp3(+)) Tregs. DHA induced T-cell hypo-responsiveness and downregulated cytokines associated with T helper (Th)-1, Th2, and Th17 cells. The differentiation of Foxp3(+) Tregs into CD4(+) T cells was directly mediated by DHA-M2 macrophages, which deactivated effector macrophages and inhibited CD4(+) T-cell proliferation. DHA showed therapeutic effects in mice with experimental atopic dermatitis. These results show that DHA enhances the function of M2 macrophages and that the generation of Tregs effectively protects mice against an inflammatory immune disorder. Thus, DHA may be a useful therapeutic strategy for treating chronic inflammatory diseases.

Methyl 5-chloro-4,5-didehydrojasmonate (J7) inhibits macrophage-derived chemokine production via down-regulation of the signal transducers and activators of transcription 1 pathway in HaCaT human keratinocytes.

Jasmonates are lipid-based stress hormones that are critical for the defense of plants against insects. Two naturally occurring jasmonates, jasmonic acid and methyl jasmonate, have recently been explored for their efficacy as anti-cancer agents. Furthermore, certain synthetic jasmonates (e.g., the cyclopentenone isoprostane J2) exert anti-inflammatory actions in lipopolysaccharide (LPS)-challenged murine macrophages via down-regulation of chemokines and other inflammatory mediators. Chemokines participate in the development and progression of many inflammatory disorders, such as atopic dermatitis (AD) and Crohn's disease, as exemplified by the role of macrophage-derived chemokine (MDC/CCL22) in the pathology of AD. The current study therefore investigated the impact of jasmonate derivatives (jasmonic acid and methyl jasmonate) and their synthetic analogues (J2 and J7) on the expression of MDC in interferon (IFN)-γ- and tumor necrosis factor (TNF)-α-stimulated HaCaT human keratinocytes, as well as the attendant mechanism of action. Jasmonic acid, methyl jasmonate, and J2 failed to inhibit the cytokine-stimulated production of MDC. By contrast, J7 suppressed the mRNA and protein expression levels of MDC in a dose-dependent manner. Moreover, J7 diminished the activation of signal transducers and activators of transcription 1 (STAT1), but had no inhibitory effect on the nuclear factor kappa B (NF-κB) or mitogen-activated protein kinase (MAPK) pathways. These results demonstrate that J7 impairs IFN-γ- and TNF-α-induced inflammatory chemokine production by targeting the STAT1 pathway.

The Chloroform Fraction of Carpinus tschonoskii Leaves Inhibits the Production of Inflammatory Mediators in HaCaT Keratinocytes and RAW264.7 Macrophages.

Inflammation is the immune system's response to infection and injury-related disorders, and is related to pro-inflammatory factors (NO, PGE2, cytokines, etc.) produced by inflammatory cells. Atopic dermatitis (AD) is a representative inflammatory skin disease that is characterized by increasing serum levels of inflammatory chemokines, including macrophage-derived chemokine (MDC). Carpinus tschonoskii is a member of the genus Carpinus. We investigated the anti-inflammatory activity of C. tschonoskii by studying the effects of various solvent fractions prepared from its leaves on inflammatory mediators in HaCaT and RAW264.7 cells. We found that the chloroform fraction of C. tschonoskii inhibited MDC at both the protein and mRNA levels in HaCaT cells, acting via the inhibition of STAT1 in the IFN-γ signaling pathway. In addition, the chloroform fraction significantly suppressed the expression of inflammatory factors induced by lipopolysaccharide stimulation, except COX-2 and TNF-α. These results suggest that the chloroform fraction of C. tschonoskii leaves may include a component with potential anti-inflammatory activity.