Effect of seasonal succession of algal communities on fouling of MF membrane.

An emerging threat to membrane application is the seasonal proliferation of algae in water sources such as rivers, reservoirs and lakes. This study investigated the link between feed parameters and the membrane performance of a pilot-scale microfiltration (MF) plant for 7 months. The seasonal succession of algae in relation to temperature dynamics was monitored. Temperature-dependent seasonal patterns for algae species were observed. The water temperatures during the dominance of cyanobacteria, especially Microcystis, were relatively higher (over 25 °C) than those during the dominance of diatoms. Diatoms did not much affect membrane performance (less than 0.2 kgf/cm2), however, under the cyanobacterial dominance condition, especially Microcystis sp., transmembrane pressure (TMP) reached up to the limited level (0.4 kgf/cm2) within one month. Concurrently UV absorbance at 254 nm wavelength and dissolved organic carbon values increased significantly during the Microcystis bloom and the build-up rate of TMP increased up to 0.005 kgf/cm2/day. Membrane autopsy also showed that during the dominance of diatom, application of cleaning agents can fully remove foulants on the membrane surface. However, during the dominance of cyanobacteria, there is a lot of Al, Si and organic complex on the fouled membrane, indicating the formation of Al-organic complexes that contributed to the residual membrane fouling. It is suggested that the irrecoverable fouling layer still contained some Al, mostly in complex with organics. Thus, organic matter originated from cyanobacteria may cause a serious impact on membrane fouling by forming the complex with metal ions originated from coagulant.

Asymmetric Host Molecule Bearing Pyridine Core for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs.

In this study, two host materials, pCzBzbCz and pCzPybCz, are synthesized to achieve a high efficiency and long lifetime of blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs). The molecular design strategy involves the introduction of a pyridine group into the core structure of pCzPybCz as an electron-withdrawing unit, and an electron-donating phenyl group into the structure of pCzBzbCz. These host materials demonstrate good thermal stability and high triplet energy (T1 =3.07 eV for pCzBzbCz and 3.06 eV for pCzPybCz) for the fabrication of blue TADF-OLEDs. In particular, pCzPybCz-based OLED devices demonstrate an external quantum efficiency (EQE) of 22.7 % and an operational lifetime of 24 h (LT90 , time to attain 90 % of initial luminance) at an initial luminance of 1000 cd m-2 . This superior lifetime could be explained by the C-N bond dissociation energy (BDE) in the host molecular structure. Furthermore, a mixed-host system using the electron-deficient 2,4-bis(dibenzo[b,d]furan-2-yl)-6-phenyl-1,3,5-triazine (DDBFT) is proposed to inhibit the formation of the anion state of our host materials. In short, the device operational lifetime is further improved by applying DDBFT. The carbazole-based asymmetric host molecule containing a pyridine core realizes a high-efficiency blue TADF-OLED showing a positive effect on the operating lifetime, and can provide useful strategies for designing new host materials.

Cumulative Experience in Lymphovenous Anastomosis for Lymphedema Treatment: The Learning Curve Effect on the Overall Outcome.

BACKGROUND: The lymphovenous anastomosis (LVA) has become one of the treatment options for lymphedema. However, it is regarded as a difficult surgery that many young microsurgeons are reluctant to try. This report investigates the learning curve in regard to symptom improvement. METHODS: This is a retrospective analysis performed in 33 consecutive lymphedema patients (38 extremities) who underwent only LVAs from August 2010 to February 2016. Surgical outcomes in regard to surgeon's experience were evaluated. The surgeons experience was divided into three groups: early group with less than 2 years, moderate with 2 to 4 years, and mature group with more than 4 years of experience. RESULTS: A total of 31 limbs (8/8 in upper extremity and 23/30 in lower extremity) showed improvement. When we compare volume change and recurrence of cellulitis with regard to surgeon's experience, there were no statistically significant differences. However, the mean time per LVA was significantly decreased as the experience increased over time (p = 0.017). CONCLUSION: LVA is an effective treatment option to reduce the volume in the affected limb and to improve symptoms involved. Regardless of the number and experience of the surgeons, cellulitis improves significantly after LVA. The experience of the surgeon does not significantly impact the positive outcome while proficiency increases with experience.

Metal-oxide assisted surface treatment of polyimide gate insulators for high-performance organic thin-film transistors.

We developed a facile method for treating polyimide-based organic gate insulator (OGI) surfaces with self-assembled monolayers (SAMs) by introducing metal-oxide interlayers, called the metal-oxide assisted SAM treatment (MAST). To create sites for surface modification with SAM materials on polyimide-based OGI (KPI) surfaces, the metal-oxide interlayer, here amorphous alumina (α-Al2O3), was deposited on the KPI gate insulator using spin-coating via a rapid sol-gel reaction, providing an excellent template for the formation of a high-quality SAM with phosphonic acid anchor groups. The SAM of octadecylphosphonic acid (ODPA) was successfully treated by spin-coating onto the α-Al2O3-deposited KPI film. After the surface treatment by ODPA/α-Al2O3, the surface energy of the KPI thin film was remarkably decreased and the molecular compatibility of the film with an organic semiconductor (OSC), 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10), was increased. Ph-BTBT-C10 molecules were uniformly deposited on the treated gate insulator surface and grown with high crystallinity, as confirmed by atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis. The mobility of Ph-BTBT-C10 thin-film transistors (TFTs) was approximately doubled, from 0.56 ± 0.05 cm2 V-1 s-1 to 1.26 ± 0.06 cm2 V-1 s-1, after the surface treatment. The surface treatment of α-Al2O3 and ODPA significantly decreased the threshold voltage from -21.2 V to -8.3 V by reducing the trap sites in the OGI and improving the interfacial properties with the OSC. We suggest that the MAST method for OGIs can be applied to various OGI materials lacking reactive sites using SAMs. It may provide a new platform for the surface treatment of OGIs, similar to that of conventional SiO2 gate insulators.

Wearable Potentiometric Chloride Sweat Sensor: The Critical Role of the Salt Bridge.

The components of sweat provide an array of potential biomarkers for health and disease. Sweat chloride is of interest as a biomarker for cystic fibrosis, electrolyte metabolism disorders, electrolyte balance, and electrolyte loss during exercise. Developing wearable sensors for biomarkers in sweat is a major technological challenge. Potentiometric sensors provide a relatively simple technology for on-body sweat chloride measurement, however, equilibration between reference and test solutions has limited the time over which accurate measurements can be made. Here, we report on a wearable potentiometric chloride sweat sensor. We performed parametric studies to show how the salt bridge geometry determines equilibration between the reference and test solutions. From these results, we show a sweat chloride sensor can be designed to provide accurate measurements over extended times. We then performed on-body tests on healthy subjects while exercising to establish the feasibility of using this technology as a wearable device.

Intranasal Introduction of Fc-Fused Interleukin-7 Provides Long-Lasting Prophylaxis against Lethal Influenza Virus Infection.

UNLABELLED: Influenza A virus (IAV) infection frequently causes hospitalization and mortality due to severe immunopathology. Annual vaccination and antiviral drugs are the current countermeasures against IAV infection, but they have a limited efficacy against new IAV variants. Here, we show that intranasal pretreatment with Fc-fused interleukin-7 (IL-7-mFc) protects mice from lethal IAV infections. The protective activity of IL-7-mFc relies on transcytosis via neonatal Fc receptor (FcRn) in the lung and lasts for several weeks. Introduction of IL-7-mFc alters pulmonary immune environments, leading to recruitment of T cells from circulation and their subsequent residency as tissue-resident memory-like T (TRM-like) cells. IL-7-mFc-primed pulmonary TRM-like cells contribute to protection upon IAV infection by dual modes. First, TRM-like cells, although not antigen specific but polyclonal, attenuate viral replication at the early phase of IAV infection. Second, TRM-like cells augment expansion of IAV-specific cytotoxic T lymphocytes (CTLs), in particular at the late phase of infection, which directly control viruses. Thus, accelerated viral clearance facilitated by pulmonary T cells, which are either antigen specific or not, alleviates immunopathology in the lung and mortality from IAV infection. Depleting a subset of pulmonary T cells indicates that both CD4 and CD8 T cells contribute to protection from IAV, although IL-7-primed CD4 T cells have a more prominent role. Collectively, we propose intranasal IL-7-mFc pretreatment as an effective means for generating protective immunity against IAV infections, which could be applied to a potential prophylaxis for influenza pandemics in the future. IMPORTANCE: The major consequence of a highly pathogenic IAV infection is severe pulmonary inflammation, which can result in organ failure and death at worst. Although vaccines for seasonal IAVs are effective, frequent variation of surface viral proteins hampers development of protective immunity. In this study, we demonstrated that intranasal IL-7-mFc pretreatment protected immunologically naive mice from lethal IAV infections. Intranasal pretreatment with IL-7-mFc induced an infiltration of T cells in the lung, which reside as effector/memory T cells with lung-retentive markers. Those IL-7-primed pulmonary T cells contributed to development of protective immunity upon IAV infection, reducing pulmonary immunopathology while increasing IAV-specific cytotoxic T lymphocytes. Since a single treatment with IL-7-mFc was effective in the protection against multiple strains of IAV for an extended period of time, our findings suggest a possibility that IL-7-mFc treatment, as a potential prophylaxis, can be developed for controlling highly pathogenic IAV infections.

Diketopyrrolopyrrole: brilliant red pigment dye-based fluorescent probes and their applications.

The development of fluorescent probes for the detection of biologically relevant species is a burgeoning topic in the field of supramolecular chemistry. A number of available dyes such as rhodamine, coumarin, fluorescein, and cyanine have been employed in the design and synthesis of new fluorescent probes. However, diketopyrrolopyrrole (DPP) and its derivatives have a distinguished role in supramolecular chemistry for the design of fluorescent dyes. DPP dyes offer distinctive advantages relative to other organic dyes, including high fluorescence quantum yields and good light and thermal stability. Significant advancements have been made in the development of new fluorescent probes based on DPP in recent years as a result of tireless research efforts by the chemistry scientific community. In this tutorial review, we highlight the recent progress in the development of DPP-based fluorescent probes for the period spanning 2009 to the present time and the applications of these probes to recognition of biologically relevant species including anions, cations, reactive oxygen species, thiols, gases and other miscellaneous applications. This review is targeted toward providing the readers with deeper understanding for the future design of DPP-based fluorogenic probes for chemical and biological applications.

A bifunctional colorimetric fluorescent probe for Hg(2+) and Cu(2+) based on a carbazole-pyrimidine conjugate: chromogenic and fluorogenic recognition on TLC, silica-gel and filter paper.

A bifunctional fluorescent probe based on a carbazole-pyrimidine conjugate for Hg(2+) and Cu(2+) detection was designed and synthesized. Probe 3 exhibits red shifts in its absorption and fluorescence spectra with significant visual color changes in the presence of these ions. The detection limits of probe 3 for these metal ions were in the nanomolar range. The probe could also be useful as a solid optical sensor for Hg(2+) and Cu(2+).

Mid-term clinical outcomes and morphological changes after endovascular aneurysm repair of inflammatory abdominal aortic aneurysms: a single-center experience.

BACKGROUND: Endovascular aneurysm repair (EVAR) has been suggested as treatment for inflammatory abdominal aortic aneurysms (IAAA), but the actual clinical and radiological outcomes need to be evaluated. PURPOSE: To report morphological changes in EVAR of IAAAs. MATERIAL AND METHODS: Ten male patients (mean age, 67 years; range, 54-78 years) with IAAA were treated with EVAR using endovascular stent-grafts between March 2001 and January 2012. We retrospectively compared computed tomography angiography (CTA) images taken immediately (30 days after the EVAR), short-term (up to 1 year), and mid-term (beyond 1 year) to CTA images taken before the EVAR. Clinical success was defined as successful deployment of the stent-graft without a type I or III endoleak. Morphologic responses of IAAA to EVAR were reviewed by measuring the changes in aneurysm sac maximum diameter (mm), periaortic fibrosis (PAF) thickness (mm), and PAF enhancement (Hounsfield units [HU] on delayed CTA) on serial images. RESULTS: Ten IAAA patients treated with EVAR were followed for a mean of 42 months (range, 7-129 months). No aneurysm-related deaths were observed during the follow-up of 10 patients. Primary clinical success was achieved in seven patients, assisted primary clinical success in one patient, and secondary clinical success in two patients. Aneurysm sac maximum diameter decreased in all patients (mean percentage reduction of 7.6%, 8.5%, and 17.3% in immediate, short-term, and mid-term follow-up CTA, respectively). PAF thickness decreased in eight patients (10.4%, 16.8%, and 27.2% regression upon follow-up). PAF enhancement decreased in nine patients and increased in one patient (mean percentage decrease of 13.0%, 27.3%, and 40.8% upon follow-up). CONCLUSION: Treatment of IAAA with EVAR was effective and reduced aneurysmal sac diameter and the extent of PAF with acceptable morbidity.

Multi-lineage differentiation of human mesenchymal stromal cells on the biophysical microenvironment of cell-derived matrix.

We obtained fibroblast- (FDM) and preosteoblast- (PDM) derived matrices in vitro from their respective cells. Our hypothesis was that these naturally occurring cell-derived matrices (CDMs) would provide a better microenvironment for the multi-lineage differentiation of human mesenchymal stromal cells (hMSCs) than those based on traditional single-protein-based platforms. Cells cultured for 5-6 days were decellularized with detergents and enzymes. The resulting matrices showed a fibrillar surface texture. Under osteogenic conditions, human bone-marrow-derived stromal cells (HS-5) exhibited higher amounts of both mineralized nodule formation and alkaline phosphatase (ALP) expression than those cultured on plastic or gelatin. Osteogenic markers (Col I, osteopontin, and cbfa1) and ALP activity from cells cultured on PDM were notably upregulated at 4 weeks. The use of FDM significantly improved the cellular expression of chondrogenic markers (Sox 9 and Col II), while downregulating that of Col I at 4 weeks. Both CDMs were more effective in inducing cellular synthesis of glycosaminoglycan content than control substrates. We also investigated the effect of matrix surface texture on hMSC (PT-2501) differentiation; soluble matrix (S-matrix)-coated substrates exhibited a localized fibronectin (FN) alignment, whereas natural matrix (N-matrix)-coated substrates preserved the naturally formed FN fibrillar alignment. hMSCs cultured for 4 weeks on N-matrices under osteogenic or chondrogenic conditions deposited a greater amount of calcium and proteoglycan than those cultured on S-matrices as assessed by von Kossa and Safranin O staining. In contrast to the expression levels of lineage-specific markers for cells cultured on gelatin, FN, or S-matrices, those cultured on N-matrices yielded highly upregulated levels. This study demonstrates not only the capacity of CDM for being an effective inductive template for the multi-lineage differentiation of hMSCs, but also the critical biophysical role that the matrix fibrillar texture itself plays on the induction of stem cell differentiation.

Blocking the receptor for advanced glycation end product activation attenuates autoimmune myocarditis.

BACKGROUND: The Receptor for Advanced Glycation End Products (RAGE) is a pattern recognition receptor for endogenous ligands, and is associated with various inflammatory diseases. However, the role of RAGE activation in myocarditis has yet to be examined. The potential role of RAGE in the development of experimental autoimmune myocarditis (EAM) and the effect of RAGE blocking in attenuating the inflammation in the EAM was investigated. METHODS AND RESULTS: EAM was evoked in Lewis rats by immunization with porcine cardiac myosin. Soluble RAGE (sRAGE) was injected to block RAGE activation. Echocardiogram, histological, and immunohistochemical examinations were conducted on days 21 and 42. In rats with EAM, RAGE expression in cardiac tissue was prominent on day 21. Rats administered sRAGE during the early antigen-priming phase showed marked attenuation in acute and chronic inflammation compared with untreated rats. RAGE expression was significantly reduced in rats treated in the early phase. However, sRAGE administration, after the initial antigen-priming phase, failed to ameliorate EAM development. CONCLUSIONS: RAGE expression was significantly increased in the heart during EAM. Blocking RAGE activation with sRAGE during the early antigen-priming phase reduced acute and chronic inflammation and improved cardiac function. In contrast, blocking RAGE after the early phase did not attenuate EAM development. These results imply that RAGE is involved in regulating innate immune responses during the early phase of myocarditis development.

Thin superficial circumflex iliac artery perforator flap and supermicrosurgery technique for face reconstruction.

Distant free flaps have become a routine option for reconstruction of large, complicated facial soft tissue defects. The challenge is to find a flap that is pliable to provide good contour and function. The purpose of this paper was to evaluate the use of superficial circumflex iliac artery perforator (SCIP) flaps for facial defects. From November 2010 to June 2013, facial reconstruction was performed on 6 patients (age range, 15-79 years). The harvesting technique was modified to elevate above the deep fat, and the pedicles were taken above or just below the deep fascia. The mean size of the flap was 75.6 cm2, with a thickness of 7 mm; the mean pedicle length was 4.9 cm; and the mean artery caliber was 0.7 mm. The supermicrosurgery technique was used successfully in all 6 cases. Donor sites were all closed primarily. The mean follow-up was 16.7 months. All flaps survived without flap loss, and the donor sites healed without complications including lymphorrhea. The patients were satisfied with contour and function after reconstruction. The result of these 6 cases suggested that the SCIP flap can be a reliable flap for moderate-sized to large defects in the face. The use of new instrumentation and supermicrosurgical techniques allows use of the SCIP flap reliably while providing patients with a good contour, function, and minimal donor site morbidity.

A new plane of elevation: the superficial fascial plane for perforator flap elevation.

BACKGROUND: The aim for microsurgical reconstruction has broadened from achieving functional to also providing good esthetic outcomes. The perforator flaps are widely used for this goal. However, perforator flaps can still be bulky especially to resurface the skin defect. We hypothesized that elevation from the superficial fascial plane can obtain a thin and viable flap. METHOD: In this retrospective study, we report consecutive perforator flaps elevated at the superficial fascial plane from November 2007 to July 2013. Total of 304 flaps which were 196 superficial circumflex iliac perforator (SCIP) flaps, 81 anterolateral thigh (ALT) flaps, and 27 gluteal artery perforator (GAP) flaps were reviewed. RESULT: The patient group composed of 189 male and 115 female patients with an average age of 35.8 years. The average body mass index was 23.5 kg/m(2) (range, 15.91-34.57 kg/m(2)). All 304 flaps were successfully elevated with this approach with at least one viable perforator. The thickness averaged approximately 6 mm for ALT flap (range, 4-11 mm), 5 mm for SCIP flap (range, 3-12 mm), and 8.5 mm for GAP flap (range, 5-11 mm). Complete survival was noted in 282 flaps, partial loss of flaps requiring secondary procedures in 6 cases, partial loss healing secondarily in 8 cases, and total loss in 9 cases. During the average follow-up of 34 months, secondary debulking procedures were required in six flaps. CONCLUSION: This new approach of elevation on the superficial fascia is reliable, provides a viable tissue, and is able to obtain a thin flap achieving good functional and esthetic outcome.

Precision-Engineered Medium-Sized Molecular Host and Emitter for Ensuring Consistent Performance in Solution-Processed Narrowband OLEDs.

In this study, two novel multiple resonance (MR) emitters, DtCzBN and Cy-DtCzBN, were designed based on the well-known BCzBN structure and synthesized for narrowband solution-processed organic light-emitting diodes (OLEDs). Cy-DtCzBN possesses a dimeric V-shaped structure formed by coupling two individual DtCzBN units via a nonconjugated cyclohexane linker. When compared with DtCzBN, Cy-DtCzBN, as a medium-sized molecule, was found to maintain the optical and photophysical properties of the corresponding monomeric unit, DtCzBN, but exhibits high thermal stability, excellent solubility, and good film-forming ability. Additionally, solution-processed OLEDs were fabricated by using two sets of molecules: one set of small molecular hosts and emitters (i.e., mCP and DtCzBN) and the other set of medium-sized molecular hosts and emitters (i.e., Cy-mCP and Cy-DtCzBN). Notably, devices using medium-sized molecular hosts and emitters exhibited similar optical and photophysical properties but showed significantly improved reproducibility and thermal stability compared with those based on small molecular hosts and emitters. Our current study provides some insights into molecular design strategies for thermally stable hosts and emitters, which are highly suitable for solution-processed OLEDs.

Effect of intramolecular energy transfer in a dual-functional molecular dyad on the performance of solution-processed TADF OLEDs.

This paper introduces the design concept of a dual-functional molecular dyad tailored specifically for solution-processable organic light-emitting diodes (OLEDs). Cy-tmCPBN, characterized by an asymmetric molecular dyad structure, integrates a host unit (tmCP) and a multiple-resonance (MR) emitter (CzBN) via a non-conjugated cyclohexane linker. Cy-tmCPBN exhibited efficient intramolecular energy transfers (EnTs) from tmCP to the CzBN unit, as confirmed by time-resolved fluorescence experiments. The fluorescence lifetime of the tmCP unit was approximately three times shorter in a highly diluted solution of Cy-tmCPBN than in a mixed solution of Cy-tmCP and Cy-CzBN. In addition, Cy-tmCPBN exhibited excellent solubility and film-forming ability, making it suitable for solution processing. Notably, OLEDs utilizing Cy-tmCPBN achieved over twice the brightness and improved external quantum efficiency of 12.3% compared to OLEDs using Cy-CzBN with the same concentration of CzBN in the emitting layer. The improved OLED performance can be explained by the increased EnT efficiency from Cy-tmCP to Cy-tmCPBN and the intramolecular EnT within Cy-tmCPBN. In our dual-functional dyad, incorporating both host and emitter units in an asymmetric molecular dyad structure, we induced a positive synergy effect with the host moiety, enhancing OLED performance through intramolecular EnT.

Polymer Hosts Containing Carbazole-Dibenzothiophene-Based Pendants for Application in High-Performance Solution-Processed TADF-OLEDs.

The film-forming capability of the host plays a crucial role in effectively forming a light-emitting layer through a solution process in organic light-emitting diodes (OLEDs). In this study, we synthesized two side-chain polymer hosts, PCz-DBT and P2Cz-DBT, consisting of carbazole and dibenzothiophene. The synthesis was carried out through radical polymerization using styrene-based host monomers. Their photophysical characteristics and molecular energy levels are similar to those of the reference small molecule hosts, namely, Cz-DBT and 2Cz-DBT. However, compared to the small-molecule hosts Cz-DBT and 2Cz-DBT, the two polymer hosts showed high thermal stability and good film-forming properties in the neat and host-emitter blend films. Specifically, bluish-green multiple-resonance (MR) thermally activated delayed fluorescence (TADF) OLEDs, fabricated via solution processing with an emissive layer based on P2Cz-DBT, exhibited remarkable performance. These devices achieved a maximum external quantum efficiency of 17.4% without utilizing a hole transport layer. This polymer host design strategy is considered to significantly contribute to enhancing the performance of TADF-OLEDs fabricated through solution processing.

Dual growth factor delivery using biocompatible core-shell microcapsules for angiogenesis.

An optimized electrodropping system produces homogeneous core-shell microcapsules (C-S MCs) by using poly(L-lactic-co-glycolic acid) (PLGA) and alginate. Fluorescence imaging clearly shows the C-S domain in the MC. For release control, the use of high-molecular-weight PLGA (HMW 270 000) restrains the initial burst release of protein compared to that of low-MW PLGA (LMW 40 000). Layer-by-layer (LBL) assembly of chitosan and alginate on MCs is also useful in controlling the release profile of biomolecules. LBL (7-layer) treatment is effective in suppressing the initial burst release of protein compared to no LBL (0-layer). The difference of cumulative albumin release between HMW (7-layer LBL) and LMW (0-layer LBL) PLGA is determined to be more than 40% on day 5. When dual angiogenic growth factors (GFs), such as platelet-derived GF (PDGF) and vascular endothelial GF (VEGF), are encapsulated separately in the core and shell domains, respectively, the VEGF release rate is much greater than that of PDGF, and the difference of the cumulative release percentage between the two GFs is about 30% on day 7 with LMW core PLGA and more than 45% with HMW core PLGA. As for the angiogenic potential of MC GFs with human umbilical vein endothelial cells (HUVECs), the fluorescence signal of CD31+ suggests that the angiogenic sprout of ECs is more active in MC-mediated GF delivery than conventional GF delivery, and this difference is significant, based on the number of capillary branches in the unit area. This study demonstrates that the fabrication of biocompatible C-S MCs is possible, and that the release control of biomolecules is adjustable. Furthermore, MC-mediated GFs remain in an active form and can upregulate the angiogenic activity of ECs.

An unsymmetrically π-extended porphyrin-based single-crystal field-effect transistor and its anisotropic carrier-transport behavior.

Anisotropic charge transport: Single-crystal organic field-effect transistor devices derived from aggregates of thiophene-appended porphyrins display very high mobility (0.27 cm(2) V(-1) s(-1)). This behavior is due to staircase stacking of the porphyrins with distances between layers of 3.17(7) Å. Furthermore, the charge-transport behavior is anisotropic owing to an anisotropic molecular arrangement in the single-crystal microplates.

Enhanced Efficiency and Stability of Novel Pseudo-ternary Polymer Solar Cells Enabled by a Conjugated Donor Block Copolymer.

The recent breakthrough in power conversion efficiencies (PCEs) of polymer solar cells (PSCs) that contain an active layer of a ternary system has achieved values of 18-19%; this has sparked interest for further research. However, this system has difficulties in optimizing the composition and controlling the interaction between the three active materials. In this study, we investigated the use of a donor1 (D1)-donor2 (D2) conjugated block copolymer (CBP), PM6-b-TT, to replace the physical blend of two donors. PM6-b-TT, which exhibits an extended absorption range, was synthesized by covalently bonding PM6, a medium-band gap polymer, with PBDT-TT, a wide-band gap polymer. The blend films containing PM6-b-TT and Y6-BO acceptor, demonstrated excellent crystallinity and a film morphology favorable for PSCs. The corresponding pseudo-ternary PSC exhibited significantly higher PCE and thermal stability than the PM6:PBDT-TT-based ternary device. This study unambiguously demonstrates that the novel D1-D2 CBP strategy, combined with the conventional binary and ternary system advantages, is a promising material production strategy that can boost the performance of future PSCs.

Stretchable Semiconducting Polymers with Hydrogen-Bonding-Capable Conjugation Breakers: Synthesis and Application in Organic Thin-Film Transistors.

Diketopyrrolopyrrole (DPP)-based conjugated copolymers are important organic semiconductors for applications in high-efficiency organic thin-film transistors (OTFTs). However, the direct application of these polymers with rigid backbones in stretchable devices has limitations. In this study, we designed and synthesized three kinds of DPPBT-based copolymers, DPPBT-A1, DPPBT-A3, and DPPBT-A5, which have amide-coupled alkylene conjugation breakers capable of hydrogen bonding. Linkers with different segment lengths were copolymerized with DPP and bithiophene (BT) backbone units. A DPP-based copolymer with alternating BT moieties, DPPBT, was synthesized as a reference fully conjugated copolymer. The synthesized polymers with freely rotational backbone linkers have sufficient flexibility to develop ordered phase domains, even in thin films, in comparison to the reference copolymer. However, the introduction of the conjugation breakers, which disconnect the intramolecular π-π overlapping, tends to decrease the hole mobility (µ) from 0.76 to 0.20 cm2 V-1 s-1 in the corresponding OTFT devices. The TFT fabricated using DPPBT-A3 showed a mobility of 0.50 cm2 V-1 s-1, and the mobility value did not show a significant change even when elongated by more than 50%. Therefore, the molecular design strategy of introducing amide-coupled alkylene conjugation breakers into conjugated polymer chains can contribute significantly to the development of high-mobility stretchable conjugated polymers in future.