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Derivatization is essential for optimizing organic material properties. However, because functional groups are often introduced at an early stage of the synthesis, similar intermediates have to be repeatedly synthesized to produce derivatives, which amounts to a daunting and time‐consuming task. Using thienobenzobisthiazole (TBTz) as a building unit of donor polymers for organic photovoltaics (OPVs), we demonstrate an efficient derivatization of a TBTz‐based π‐conjugated polymer by late‐stage functionalization. In the developed synthetic route, functional groups are introduced at the last step of monomer synthesis, enabling us to easily synthesize several derivatives from a common intermediate. Ester and acyl groups are introduced into the polymer instead of the alkyl group, giving rise to deep HOMO energy levels and resulting in OPV cells with high open‐circuit voltage even in the absence of halogen substituents that are typically introduced into the donor polymers. Notably, the ester‐functionalized TBTz‐based polymer shows a small nonradiative voltage loss (ΔVnr) of 0.19 V and has one of the highest charge generation efficiencies among the halogen‐free donor polymers with similar ΔVnr, improving the critical trade‐off relationship between voltage loss and charge generation. Our results provide an important guideline for the efficient development of high‐performance polymers for OPVs. [ABSTRACT FROM AUTHOR]

Background/Aims: Endoscopic self-expandable metal stent (SEMS) placement is currently the standard technique for treating unresectable malignant distal biliary obstructions (MDBO). Therefore, covered SEMS with longer stent patency and fewer migrations are required. This study aimed to assess the clinical performance of a novel, fully covered SEMS for unresectable MDBO. Methods: This was a multicenter single-arm prospective study. The primary outcome was a non-obstruction rate at 6 months. The secondary outcomes were overall survival (OS), recurrent biliary obstruction (RBO), time to RBO (TRBO), technical and clinical success, and adverse events. Results: A total of 73 patients were enrolled in this study. The non-obstruction rate at 6 months was 61%. The median OS and TRBO were 233 and 216 days, respectively. The technical and clinical success rates were 100% and 97%, respectively. Furthermore, the rate of occurrence of RBO and adverse events was 49% and 21%, respectively. The length of bile duct stenosis (<2.2 cm) was the only significant risk factor for stent migration. Conclusions: The non-obstruction rate of a novel fully covered SEMS for MDBO is comparable to that reported earlier but shorter than expected. Short bile duct stenosis is a significant risk factor for stent migration. [ABSTRACT FROM AUTHOR]

This study investigates backbone engineering and evaluates the thermoelectric properties of FeCl 3 -doped naphthobisthiadiazole (NTz)-based donor-acceptor (D-A) conjugated polymer films. The NTz acceptor unit is coupled with three distinct donor units, namely dialkylated terthiophene (3T), dialkylated quaterthiophene (4T), and dialkylated bisthienyl thienothiophene (2T-TT) to yield copolymers designated as PNTz3T, PNTz4T, and PNTzTT. The difference in donor units leads to diverse molecule stacking and electronic properties, which can be systematically discovered via the three polymers. The linear structure of PNTz4T enables an orderly arrangement of side chains, thereby promoting dopant intercalation for enhanced carrier concentration. Additionally, this linear structure leads to an edge-on stacking mode, thereby improving the in-plane carrier mobility. As a result, the doped PNTz4T exhibits the highest electrical conductivity (σ) of 88.3 S cm -1 along with a Seebeck coefficient (S) of 62.2 µV K -1 , thereby achieving the highest power factor (PF) of 34.2 µW m -1 K -2 . These results highlight the relationship between the molecular design, microstructure, and doping effects in manipulating the thermoelectric performance of doped NTz-based D-A polymers., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Careful control of electronic properties, structural order, and solubility of π-conjugated polymers is central to the improvement of organic photovoltaic (OPV) performance. In this work, we designed and synthesized a series of naphthobisthiadiazole-quaterthiophene copolymers by systematically replacing the alkyl groups with ester groups and changing the position of the fluorine groups in the quaterthiophene moiety. These alterations lowered the HOMO and LUMO energy levels and systematically varied the combination of intramolecular noncovalent interactions such as O⋯S and F⋯S interactions in the backbone. More importantly, although the introduction of such noncovalent interactions often lowers the solubility owing to the interlocking of backbone linkages, we found that careful design of the noncovalent interactions afforded polymers with relatively high solubility and high crystallinity at the same time. As a result, the power conversion efficiency of OPV cells that used fullerene (PC 61 BM) and nonfullerene (Y12) as the acceptor was improved. Our work offers important information for the development of high-performance π-conjugated polymers for OPVs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)